Nicolas Barnier
email: barnier@recherche.enac.fr

Cyril Allignol
email: allignol@tls.cena.fr

Traffic Management Research and Development Seminar (ATM2009) 4D-Trajectory Deconfliction Through Departure Time Adjustment

Keywords: Slot Allocation, Conflict Resolution, Constraint Programming

As acknowledged by the SESAR programme, current ATC systems must be drastically improved to accommodate the predicted traffic growth in Europe. In this context, the Episode 3 project aims at assessing the performance of new ATM concepts, like 4D-trajectory planning and strategic deconfliction.

One of the bottlenecks impeding ATC performances is the hourly capacity constraints defined on each en-route ATC sector to limit the rate of aircraft. Previous works were mainly focused on optimizing the current ground holding slot allocation process devised to satisfy these constraints. We propose to estimate the cost of directly solving all conflicts in the upper airspace with ground holding, provided that aircraft were able to follow their trajectories accurately.

We present a Constraint Programming (CP) model of this large scale combinatorial optimization problem and the results obtained with the FaCiLe constraint library. We study the effect of uncertainties on the departure time and estimate the cost of improving the robustness of our solutions with the CATS simulator. Encouraging results were obtained without uncertainty but the costs of robust solutions are prohibitive. Our approach may however be improved e.g. with a prior flight level allocation and the dynamic resolution of remaining conflicts with one of CATS' module.

I. INTRODUCTION

In an already saturated European sky, the predicted growth of air traffic volume urges to improve Air Traffic Management (ATM) efficiency, as attested by the ACARE Strategic Agenda 2 [START_REF]Strategic research agenda 2[END_REF] and the European Single Sky programme SESAR. Current ATM optimization strategies, like reducing the size of control sectors or the distance of separation (RVSM, P-RNAV), seem to have reached the structural limits of the system, while the automation of Air Traffic Control (ATC) has known few significant improvements over the last decades [START_REF] Garot | Failures in the automation of air traffic control[END_REF].

In this context, the European Commission has launched the Episode 3 [START_REF] Graham | Preparing an initial assessment of the SESAR concept of operations "EP3: Single european sky implementation support through validation[END_REF] research project to assess the concepts studied within SESAR definition phase. Among the key concepts identified to meet SESAR performance objectives, the planning of 4D-trajectories would allow to increase en-route capacity, while preserving the current level of safety. One of the goals of the WP4 of Episode 3 is to estimate how such regulations could benefit strategic deconfliction schemes over the current Air Traffic Flow Management (ATFM) process.

Currently, the Central Flow Management Unit (CFMU) in Brussels is in charge of optimizing the traffic by, among other strategic or tactical measures, delaying departure slots for the flights involved in overloaded enroute sectors. The purpose of this ground holding scheme is to respect the en-route capacity constraints provided by each ATC Centre (ATCC) as a number of aircraft per hour, according to their daily schedule. Former studies like [START_REF] Dalichampt | Innovative slot allocation (ISA)[END_REF], [START_REF] Barnier | Slot allocation with constraint programming: Models and results[END_REF] aimed at improving this slot allocation over the greedy algorithm used at the CFMU. However, one of the limitations of this regulation model is that the definition of sectors capacities (hourly rate of aircraft entering the sector) is poorly related to the complexity of the traffic with respect to the controllers workload, as assessed by [START_REF] Gianazza | Selection and evaluation of air traffic complexity metrics[END_REF].

Instead of trying to satisfy en-route capacity constraints, we propose to directly solve the potential conflicts occurring between any two intersecting trajectories with departure time adjustements. A single delay would be associated with each flight such that all potential conflicts occurring above a given flight level would be avoided. This very fine grain model would of course generate much larger constraints sets than the macroscopic (at the sector level) capacitated ones, but would garantee conflict-free trajectories all along the flight path... provided that aircraft were able to scrupulously follow their predicted route in the four dimensions.

Obviously, the latter hypothesis is far from being met nowadays, but the accuracy of Flight Management Systems will be a crucial issue for future ATFM and ATC systems, as advocated by [START_REF] Alliot | ATM: 20 ans d'effort et perspectives[END_REF] and acknowledged by the Airbus-driven "Technological Enablers" WP6 of Episode 3. Nevertheless, we believe that our approach may reduce air traffic complexity by "deconflicting" it in advance. The remaining conflicts due to deviation from the flight plan (or occurring in the lower airspace) would then be dynamically solved either by automated resolution systems as proposed by [START_REF] Granger | Optimal resolution of en route conflicts[END_REF], [START_REF] Archambault | Speed uncertainty and speed regulation in conflict detection and resolution in air traffic control[END_REF], or by more standard ATC procedures.

Several optimization paradigms are being evaluated for this purpose, namely meta-heuristics, local search and Constraint Programming (CP). We will focus here on the CP approach as it offers to obtain proved bounds on the maximal delays needed to solve the conflicts, which can be used to draw conclusions on the feasibility of this kind of regulations. Moreover, CP is a technology of choice for implementing such preliminary work, as it allows to easily refine the problem by adding new constraints (e.g. connection constraints between flights using the same aircraft) and to experiment with various search strategies without changing the rest of the model.

In the following sections, we first briefly introduce ATC and ATFM in Europe, focusing on ground holding policies and related research projects. Then we describe our model of a conflict-free slot allocation, starting by the details of the constraints generation and search strategy. Next, our first results on instances of the French Traffic are presented, as well as the effect of small takeoff time uncertainties. We end with planned further works to enhance the approach before concluding.

II. CONTEXT AND RELATED WORKS

A. ATC and ATFM

Air Traffic Control (ATC) is a ground-based service provided to ensure the safety and efficiency of the flow of aircraft. The first goal of ATC is to maintain aircraft separated: outside Terminal Areas (TMA) around airports, two aircraft should remain distant from each other at least by 5 NM horizontally and 1000 ft vertically, as illustrated by the safety volume of figure 1.

The overall system currently implemented in Europe to achieve this goal can be conceptually divided in several layers or filters with decreasing time horizon with respect to the flight date of the traffic concerned: We will focus in the following section on the kind of regulations performed by the CFMU by postponing the takeoff of aircraft.

B. Ground Delays

As aircraft obviously cannot be paused while airborne whenever the traffic complexity becomes too high to be safely handled by a controller, one of the simplest way to leverage ATC workload is to postpone the takeoff of aircraft1 . This kind of measure is however quite unpopular among airlines, as it can be very costly and may propagate in terms of missed correspondances and aircraft rotation (see [START_REF]Evaluating the true cost to airlines of one minute of airborne or ground delay[END_REF]), so the delays should be minimized as much as possible.

1) Satisfying En-Route Sectors Capacity Constraints:

The aim of CFMU regulations is to maintain the number of en-route aircraft entering a given subset of sectors below some bound over given time periods (usually one hour), according to the constraints declared by experts (FMP) in each ATCC for the day of traffic. The CFMU experts first identify the overloaded sectors and responsible flows with the PREDICT tool, then compute a slot allocation as ground delays for the involved flights with the CASA tool (cf. [START_REF]Basic CFMU Handbook -General & CFMU Systems[END_REF]).

CASA is able to take into account many operational constraints and updates to optimize its allocation process, but the algorithm used has greedy properties and thus cannot guarantee to find a correct solution (which satisfies all the constraints) or an optimal one. CP technology has been applied with good results to prove and optimize the allocation process with a relaxed model [START_REF] Dalichampt | Innovative slot allocation (ISA)[END_REF] or to smooth the resulting load profiles [START_REF] Barnier | Slot allocation with constraint programming: Models and results[END_REF] with a tighter model.

However, traffic complexity is very hard to define precisely, and sector capacities, expressed as a maximum number of aircraft entering the sector over a given time period, does not take into account many parameters relevant to accurately represent the performance of ATC. Observed actual capacities, as well as merging and splitting subset of sectors, symptomatically present very different profiles than the predicted ones.

To overcome this issue, recent works such as [START_REF] Flener | Air-traffic complexity resolution in multisector planning using constraint programming[END_REF] use a much more precise and complex workload CP model to dynamically balance the traffic over the sectors of an ATCC in the upper airspace. Other works, like [START_REF] Barnier | Application de la programmation par contraintes à des problèmes de gestion du trafic aérien[END_REF] uses CP technology as well to optimize the ATCC opening schedules to match the predicted traffic more closely, or even attempt to redesign airspace sectorisation with better balancing like [START_REF] Huy | Airspace sectorization by constraint programming[END_REF].

2) Solving the Conflicts: One of the key ATM operational concept of the SESAR programme that Episode 3 should validate is the design of conflict-free 4D-tubes within crowded airspace (whereas separation could be delegated to aircraft in less dense areas). So instead of only respecting sectors capacities macroscopically, we propose to evaluate the cost of precisely solving all potential conflicts, only by ground holding, while minimizing the worst allocated delay to maintain equity among airlines.

Optimality proofs for the overall sum of the delays can be exponentially harder than our max criterion, and therefore out of reach for such large problems. However, our search strategy will focus on maintaining the overall amount of delay as low as possible, while the use of CP technology will provide proved maximal delay bounds that other optimization techniques (e.g. local search or meta-heuristics) cannot produce.

This conflict-free model will of course yield much larger problem instances as all the conflicting trajectories intervals above a given flight level will be taken into account as constraints. The resulting problem is intrinsically disjonctive as for each potential conflict between two flights i and j, either i must precede j or j precede i at each pair of points concerned (see section III-B).

Other approaches have been presented to solve conflicts in real-time, automating the task of controllers. Some of the most promising ones are centralized techniques that compute simple horizontal or vertical manoeuvres [START_REF] Granger | Détection et résolution de conflits aériens : modélisations et analyse[END_REF] and small speed adjustements as proposed by the ERASMUS project [START_REF] Archambault | Speed uncertainty and speed regulation in conflict detection and resolution in air traffic control[END_REF]. These solvers, based around a meta-heuristic (Genetic Algorithm), can take uncertainties on ground and vertical speed into account and repeatedly compute solutions for a sliding time window.

III. CONFLICT-FREE SLOT ALLOCATION

A. Conflict Detection

Our data are provided by the CATS2 simulator [START_REF] Alliot | CATS: A Complete Air Traffic Simulator[END_REF], which takes as input all filed flight plans concerning the French airspace for a given day of traffic and the relevant airspace configuration (sectors, waypoints...), and outputs the corresponding 4D-trajectories. Trajectories are sampled with a 15 s time step, which is the largest interval to guarantee that at least two points of the trajectories of facing aircraft at the highest possible speed will be closer than one separation norm, i.e. even the shortest conflicts will be detected.

p i k p j l i j d < 5 Nm & d < 1000 ft h v

Fig. 2. Conflicting Points Detection

Trajectories are then probed pairwise for potential conflicts, taking the maximal allowed delay into account. The separation norm is thus tested for each pair of points of the two probed trajectories (up to p = 900 points per trajectory for up to n = 9500 flights in O(n 2 p 2 )) as illustrated on figure 2 in the horizontal plane.

Though the maximal allowed delay can be seen as a parameter of the search algorithm only, it also affects the conflict detection. Actually, when the maximal allowed delay is increased, the size of the problem grows as well, as more and more flights tend to be in potential conflict. Ultimately, if a 24 h-delay would be allowed, the conflict detection could be done regardless of time, as any two geometrically conflicting trajectories would generate a constraint. So, whenever a particular instance has been proved inconsistent, it has to be generated again with higher values of the maximal delay, which will capture later potential conflicts on the trajectories pairs.

Operationally, flights originating outside the Eurocontrol countries cannot be delayed, so their delay variable will be fixed to 0 in our constraint model, reducing the number of variables but tightening the constraints as well and offering less opportunities for optimization. Constraints corresponding to conflicts occurring between two such flights will of course be discarded as we cannot delay the flights to solve them. Such remaining conflicting cases would have to be taken care of by other ATC or ATFM techniques that we will not address in this study.

B. CP Model 1) Conflicts Constraints:

To compute the constraints of our model, the trajectories are pairwise probed for couples of conflicting points. Given a flight i, we note the input data:

• {p k i } the chronologically ordered sequence of the 3D-points of its trajectory;

• t k i the time at which the flight will be at point p k i , should it not be delayed.

We define a set D of decision variables:

D = {δ i , ∀i ∈ [1, n]}
of finite domain [0, max delay] that represent the delay associated with each of the n flights, and we will describe our model using the following auxilliary variables:

• θ k i = t k i + δ i the date at which flight i will be at point p k i if it is delayed by δ i ; • d ij = δ j -δ i the
difference of the delays of flight j and i.

For any geometrically conflicting points p k i and p l j such that the separation norm is violated (d h being the distance in the horizontal plane and d v in the horizontal plane):

d h (p k i , p l j ) < 5 NM and d v (p k i , p l j ) < 1000 ft
we must temporally ensure that:

θ k i = θ l j
which can be rewritten with the difference variables d ij :

d ij = t k i -t l j
Starting at the first such point p k i that conflicts with a point of flight j, we take into account the whole continuous segment of trajectory j conflicting with p k i :

{p l j , ∀l ∈ [l k , l k+r ]}
for some r, and we impose that:

d ij ∈ {t k i -t l j , ∀l ∈ [l k , l k+r ]} d ij ∈ [lb k , ub k ]
with lb k and ub k being respectively the lower and upper bound of the set of t k i -t l j . If the next point p k+1 i of the trajectory of flight i conflicts with a further segment of flight j, we will obtain another forbidden segment for d ij :

d ij ∈ [lb k+1 , ub k+1 ]
taking part in the same potential conflict. To ensure separation we must then impose:

d ij ∈ [min(lb k , lb k+1 ), max(lb k , lb k+1 )]
as the conflicting segments of flight j overlap.

So if we take into account all the successive points of flight i, starting at p k i , that conflict with overlapping segments of flight j, up to some last point p k+s i , with lb 1 = min{lb k+u , u ∈ [0, s]} and ub 1 = max{ub k+u , u ∈ [0, s]} being the overall lower and upper bounds of the corresponding forbidden intervals for d ij , we can define the first conflict between flights i and j:

d ij ∈ [lb 1 , ub 1 ]
Note that we take as parameters of the problem instance the maximal allowable delay δ i ∈ [0, max delay], therefore the domain of d ij = δ j -δ i is the interval [-max delay, max delay]. We simply discard the conflict whenever ub < -max delay or lb > max delay.

A pair of flights may conflicts several disjoint times over their entire trajectories (as illustrated on figure 3), so several such disjoint intervals may be forbidden for the difference of their delays. For two flights i and j conflicting σ times over their entire trajectories:

d ij ∈ [lb 1 , ub 1 ] ∪ • • • ∪ [lb σ , ub σ ]
or, rewritten as a disjonctive constraint over the decision variables:

(-w ≤ δ j -δ i < lb 1 ) ∨ (ub 1 < δ j -δ i < lb 2 ) ∨ • • • ∨ (ub σ-1 < δ j -δ i < lb σ ) ∨ (ub σ < δ j -δ i ≤ w)
provided that lb 1 > -w and ub σ < w, otherwise the first or last part of the disjonction is removed. The cost of a solution is then defined as:

cost = max{δ i , ∀i ∈ [1, n]}
2) Further Instance Processing: The takeoff and landing part of trajectories are truncated around airports within a given radius (usually 10 NM) as the traffic is considered handled with specific procedures by the TMA control services in these zones.

After the computation of the conflict constraints, the whole instance is scaled down to a more reasonable time step (e.g. 1 min) than the 15 s used during conflict detection, ensuring that the original forbidden intervals are strictly included in the scaled ones.

Moreover, the flight level of the detected conflicts can be filtered, for example to only take into account conflicts occurring within the upper airspace (from FL290 and above). The minimal and maximal altitude of each conflict is recorded during the detection stage and a conflict is discarded if it entirely occurs below or above the specified airspace slice.

We allow as well to filter the time interval during which the conflicts may occur, taking the time bounds of the allowable delay into account. Any conflict strictly occurring outside the given time interval is then discarded.

Eventually, all the flights that do not have any conflict with any other flight are withdrawn from the instance.

3) Conflict Extension: To improve the robustness of our solutions towards uncertainty on the departure times of the flights, we add an extra parameter ext that extends conflicting intervals by a fix amount of time. Such an extension of ext minutes stretching each end of a conflict will allow to manage uncertainties of ± ext 2 minutes on the departure slot (see section IV-D), at the price of an increase in the cost of the solutions. We expect that this extension scheme may as well be able to diminish the effects of other sources of uncertainty (e.g. vertical and ground speed) regarding the number of remaining conflicts.

C. Search Strategy

The constraints of the problem are reminiscent of the disjonctive mutual exclusion constraints modelling scheduling problems. At a coarse grain, we could consider each conflicting area as a machine on which to process two tasks of different lengths (depending on the speed of the aircraft). Several conflicts along a trajectory could be seen as the ordered tasks of a given job, as in the Jobshop Scheduling Problem (JSP).

However, the comparison does not hold much further. First, the time intervals between any two conflict tasks of the same trajectory is fixed, as only one delay variable is associated with each flight (unlike the JSP where all tasks are only related with precedence constraints). Second, to consider a potential conflict in three dimensions only, as the transitive closure of the overlapping conflicting segments, with task lengths proportional to the time spent by the aircraft within the area, is misleading. In this setting, the conflict associated with two catching-up flights on the same route would be the entire trajectory, preventing them from being airborne at the same time! Obviously, our model is much more precise and allows two aircraft on the same route being only separated by 5 NM. Third, the number of "conflict machines", if not quadratic in the number of "flight jobs" as it could ultimately grow for arbitrary instances, is quite huge anyway as shown on figure 5.

Nevertheless, the branching scheme of our search strategy is inspired by standard scheduling techniques, because the essentially disjonctive nature of our problem shares some issues with scheduling ones. Trying to start the search by labelling the delay variables δ i would be highly inefficient, because the constraints are expressed over the differences d ij . Much more filtering is obtained by feeding the propagation of the arithmetic constraints with new domain bounds for the d ij auxilliary variables.

Similarly to some scheduling branching schemes, where tasks performed on the same machine are ordered pairwise (either task A precedes task B or B precedes A), we either add the constraint d ij < lb or d ij > ub in the case of a single conflicting interval. If there are several holes in the domain of d ij , branching is repeated with the bounds of the remaining holes. The variable d ij with highest sparsity, i.e. the smallest ratio between the domain size and the difference of the domain bounds, is chosen first for branching.

To compensate for the cost being defined as the maximal delay only, disregarding the total amount of time, we choose to branch first within the d ij interval corresponding to the minimum potential increase for its delay variables δ i and δ j . Such an interval would be the closest to 0. Whenever the search backtracks over such a decision, this interval is discarded and we branch on the next one recursively.

When all conflicts are ordered and there is no more holes in the domain of the d ij , we start labelling the decision variables δ i with a standard dom/deg selection heuristic and the values closest to 0 are probed first so as to reduce the total amount of delay.

After the first solution is found, the branch and bound algorithm then proceeds by dichotomy on the cost domain to find the optimal solution with respect to minimization of the maximal allocated delay.

IV. RESULTS

We have implemented this CP model with the FaCiLe library [START_REF] Barnier | FaCiLe: a Functional Constraint Library[END_REF] and obtained the following results on various day of traffic in 2007, with up to 9500 flights and 600 000 intersecting pairs of trajectories taken into account for the largest instances we could optimally solve. About 10% of the flights are non-European flights, their delays will therefore be fixed to 0 as aforementioned.

A. Data Processing

The resulting constraint graphs typically exhibit only one single large connected component of maximal degree that can be greater than 300, i.e. a single flight may conflict with more than 300 other flights. Large cliques can also be found, as large as involving more than 60 flights, which indicates the presence of very entangled and dense traffic areas. The hardness of the conflict constraints is quite unevenly distributed, with two peaks for respectively very small and very large forbidden intervals.

We mainly tune the size of our instances by choosing the minimal flight level for which the conflicts are taken into account, aiming at the upper airspace (above FL290) where most of the cruising traffic occurs. However, we were able to optimally solve one instance with more than 6 600 flights and 630 000 conflicting pairs, taking all conflicts into account for the whole day, regardless of the flight level. Figure 4 shows the number of flights of our instances as a fonction of the minimal FL. The plots present two parts, one very steep from the maximal FL to FL300, then flights add up at a slower rate in the lower airspace -note that plots are labelled with their date and the type of routes (standard or direct), e.g. "070123s" for the day of traffic on the 23rd of january 2007 with standard routes. The number of conflicting pairs is not quite quadratic with the number of flights, as mentioned in section III-B and shown on figure 5, but is quite huge anyhow, reaching 630 000 for our largest instance as aforementioned.

B. Numerical Results

We were systematically able to obtain optimal solutions within affordable computation times for all the instances where the 4 GB memory of our Core 2 Duo at 2.4 GHz were not exhausted. However, the search strategy exposed in section III-C was not always the best, depending on the kind of the instances.

As shown in figure 6, small instances are solved in a few seconds whereas the biggest ones could take almost one minute, growing only quadratically with the number of flights. We plan to address larger instances, hopefully European ones, on a computer with more memory. However, the cost of this conflict-free slot allocation can be quite high for the busiest days (our worst case is 182 min above FL350), but may be more reasonable (around 60-90 min) for less crowded days. Figure 7 shows that the cost grows steadily for small instances (i.e. at high minimal FL), but jumps as soon as we add the main flows of traffic around FL350 for bigger instances. The optimal cost then seems to be stable for larger instances, triggered only by the flights added around FL350.

The corresponding overall delay sum (figure 8) and percentage of delayed flights (figure 9) exhibit of course a more steady behaviour, dramatically increasing with the largest instances only. Even if we do not optimize these criteria, the effectiveness of our search strategy can be observed as our figures remain within typical CFMU bounds -note that Eurocontrol reported a mean delay of 25-30 min per delayed flights and a percentage of about 40-55% delayed departures for september 2008.

C. Standard and Direct Routes

For one of the days of traffic (plots labelled "070123s" and "070123d"), we have also tested our model on direct routes, i.e. aircraft fly in straight line at the requested flight level from origin to destination, disregarding the waypoints of their flight plan (which we call standard routes). Direct routes are the ideal trajectories for airlines, with respect to operational cost, but such a traffic would be hardly controllable for human operators and ATC would have to be fully automated in this context. However, they tend to generate constraint graphs with a lower tightness (see figure 5), and it is interesting to observe that overall delay sums are smaller than the standard ones on figure 8. Flights following standard routes tend to be on closer trajectories, suitable for the efficiency of current ATC procedures, but not using airspace to its full capacity. The max cost can be greater with direct routes though, depending on the day of traffic, as observed on figure 7.

D. Robustness Towards Uncertainty

Our model and algorithm were validated by taking the generated solutions as input delays for the CATS simulator. We observed that the few remaining conflicts occur below the chosen minimal flight level only, or involve flights originating outside the Eurocontrol area, which cannot be delayed in our model (see section III-A).

However, this first validation does not take into account any uncertainty w.r.t. departure time or aircraft navigation. To assess the robustness of our solutions, we have added an uncertainty parameter err on departure times within CATS. Takeoffs are randomly shifted by a bounded amount of time uniformly 3 chosen in the interval [-err 2 , + err 2 ]. New validation tests were carried out with various values of parameters err and ext to compensate for the uncertainties. As expected, figure 10 shows that for ext ≥ err, no conflict remains: all points below the ext = err dashed line on the xy-plane exhibit a conflict percentage equal to zero. Above this line, the ratio of 3 A better approach would involve a statistical analysis to approximate the probability distribution of the discrepancy between scheduled and actual takeoff times. However, increasing the ext parameter leads to an increase in the total amount of delay as illustrated in figure 11. The added delays can be far too costly for higher values of ext, especially for large instances. So we cannot hope to solve all conflicts with this technique alone within CFMU (-5/+10 min) or even SESAR (±3 min) time slot objectives, as operational delay cost would be prohibitive. As presented in the next section, other regulation or dynamic resolution techniques may be used to overcome this issue.

V. FURTHER WORK

These first results are encouraging but we have only addressed so far the resolution of conflicts within the French airspace. However, in a unified European ATC context, all conflicting traffic throughout the Eurocontrol countries should be taken into account. Such instances would comprise up to 30 000 flights per day. We plan to experiment with various refinements of our algorithm to address such large scale problems.

A. Prior Flight Level Allocation

To be able to address such large instances as aforementioned, while maintaining reasonable maximal delay figures, we also plan to combine our slot allocation algorithm with a prior flight level allocation, possibly using CP technology as described in [START_REF] Barnier | Graph coloring for air traffic flow management[END_REF]. This first step, computed to minimize horizontally conflicting flows by separating them vertically (trying as well to deviate as little as possible from requested FLs), is expected to deconflict the traffic in a substantial amount before time slot allocation. The optimal cost should then remain within much better bounds than with the raw traffic.

B. Sliding Time Windows

For large European instances, we also plan to adapt our algorithm to repeatedly solve slices of the problem on a limited time window T w , then to keep only the earliest part of the solution over a smaller interval λ and to slide the resolution window by λ. Parameters T w λ must be carefully chosen according to the computation time of the resolution and the cumulative effects of uncertainties. Similar approaches are used for dynamic conflict resolution in the CATS solver as described in [START_REF] Granger | Optimal resolution of en route conflicts[END_REF].

C. Resolution with CATS Modules

Various real-time resolution algorithms have already been implemented within the CATS simulator [START_REF] Granger | Détection et résolution de conflits aériens : modélisations et analyse[END_REF], [START_REF] Granger | Optimal resolution of en route conflicts[END_REF], [START_REF] Archambault | Speed uncertainty and speed regulation in conflict detection and resolution in air traffic control[END_REF] with very good results. We would like to assess our regulation schemes further by observing the workload of these algorithms when provided with our solutions and various kind of uncertainties, and wether the automatic resolution can cope with our delays or if the resulting manoeuvres will warp our plan entirely.

VI. CONCLUSION

We have presented a new ground holding approach to solve all potential conflicts occurring above a given flight level for a day of traffic in the French airspace. Rather than trying to respect sector capacity constraints, we model each possibly conflicting situations between any two aircraft and impose adjustements of departure times to keep them separated, with the hypothesis that aircraft could precisely follow their planned 4D-trajectories.

The resulting problem size is huge, but our CP algorithm is able to reach optimal solutions for all conflicts occurring inside the upper airspace. The resulting maximal delay, overall delay sum and ratio of delayed flights can be comparable to delays allocated by the CFMU, but for the busiest days, solving all conflicts by ground delaying can be far too costly. Nevertheless, our solutions were validated with the CATS simulator, checking that no conflict under the given flight level for a delayable aircraft remains.

We have also presented a first step toward taking uncertainties into account by extending the forbidden intervals of conflicting flights. However, an extension as small as 4 min, which is able to cope only with a ±2 minuncertainty on the departure time generates tremendous amounts of delays, far above SESAR performance objectives.

We plan to overcome these issues and further assess the possible outcomes of 4D-trajectory planning in the context of Episode 3 WP4 and address larger (European) instances with various techniques like combining our delay algorithm with a prior flight level allocation, repeatedly solving the problem on a sliding time windows or solving the remaining conflicts with a CATS resolution module.

Fig. 1 .

 1 Fig. 1. Vertical and horizontal separation. Another aircraft cannot be inside the cylinder at the same time.

Fig. 3 .

 3 Fig.3. Three potential conflicts between to flights. The gray scale corresponds to time along the trajectory, the lighter the later.

Fig. 4 .

 4 Fig. 4. Minimal flight level vs number of flights.

Fig. 5 .

 5 Fig. 5. Number of flights vs number of conflicts.

Fig. 6 .

 6 Fig. 6. Number of flights vs computation time (optimality proof) in seconds.

Fig. 7 .Fig. 8 .

 78 Fig. 7. Number of flights vs optimal cost.

Fig. 9 .

 9 Fig. 9. Number of flights vs percentage of delayed flight.

Fig. 10 .Fig. 11 .

 1011 Fig. 10. Percentage of remaining conflicts w.r.t. conflict extension and departure time error in minutes.

Note that flights might be delayed for other reasons than en-route capacity violation, like bad weather or equipment failures.

The Complete Air Traffic Simulator developped at DSNA/DTI.


Elizabeth Picard

Middle East revolutions of the 2010s against authoritarianism and corruption were quickly labelled part of the "struggle for democracy." While the term was used in vague and often contradictory manners by opponents of the incumbent regimes, street protesters and foreign supporters, its implications are manifold. As explained by T. H. Marshall in 1950, the struggle for democracy implies fighting for three sorts of rights: political rights, civil rights and social rights. 1 In the Middle East, ideas of citizenship and equality before the law are more often than not challenged because of overwhelming social and economic inequalities.

Among the citizens of a state and among the inhabitants of a country, who is entitled to social welfare, health and education? How do the inequalities of access to these rights interfere with the respect of political and civil rights? How do they contribute to representations of the self as a citizen, of the citizens as a nation, of the state as a common good?

1 As reminded by Anh Nga Longva, "Citizenship in the Gulf State.

Such questions appear obvious in several Gulf States where foreign workers have long brought a crucial contribution to economic growth while remaining excluded from national rights and wealth. By contrast, they remained understudied in the Arab Levant until recently.

Still, the labour market in Lebanon can be considered quite similar to the labour markets in Kuwait or Bahrain; the economy of Lebanon can be considered a rent economy comparable to those of the Gulf States; and the legal status and practical treatment of foreign workers in Lebanon obey the same rules known in the Gulf as kafala (sponsorship). Moreover, in Lebanon, like in the Gulf States, the foreign workers' issue underlines flaws in national building and contributes to the fragmentation of domestic ethnic and confessional groups.

Lebanon has often been labelled a 'microcosm' of the Middle East, a place to study events and trends which would soon spread in the Arab East. In this time of social upheaval and political change in the Arab world, the case of Lebanon and the current situation of Asian migrant workers in Lebanon might offer an insight into the future of the Gulf states.

An often heard self-satisfied comment on the Uprisings in the surrounding Arab countries is either that Lebanon, having long been a paragon of democracy did not need a revolution like its neighbors or, alternatively, that it was the first nation in the Arab world to lead a successful popular intifadha in the Spring of 2005, which obtained the rapid withdrawal of the Syrian occupation forces.

Eight years later this optimistic judgment remains questionable: notwithstanding the dramatic episodes of the summers of 2006 (the Israeli war over Lebanon) and 2007 (the army war against an Islamist insurgency in Nahr al-Barid), the local political scene is characterized by a toxic stalemate between two rival coalitions: the "8 March" parties dominated by Hezbollah and supported by Syria and Iran; and the "14 March" forces under the leadership of the Hariri's Future Party which is allied with the Saudis and the West. Since 2005, expectations for constitutional reform and public accountability have diminished year by year, and street politics have turned more violent every year.

Yet, the Arab Uprisings, especially the demonstrations in Tahrir square in Cairo and the mobilizations in Syria have resounded in civil society associations in Lebanon as well as among militant organizations. "Here *in Lebanon+, it was heard, we don't suffer from one dictator but from eighteen [in reference to the leaders of legally empowered confessional groups+." 2 Calls for constitutional reform, the suppression of the sectarian system and reining in its ruling elite mobilized more than 3,000 people on 27 February 2011, 10,000 and 25,000 people on 6 and March 20, in rallies called respectively by Leftist, democratic secular collectives, independent activists and political parties such as the Lebanese Communist Party (LCP) and the People's Movement. 3 It was the birth of several campaigns and gatherings outside the 14 and 8 March polarisation and the classical left. Civil movements were mainly motivated by the inability of Lebanon's ruling class to deliver structural reform. The movements acquired new layers of activists around the country, such as the Haqqi 'alayyi ('my right') campaign in Beirut, the 'Tripoli without arms campaign', the 'Civil Forum' in the Biqaa, and the 'Amal mubashar ('Direct Action'), a coalition of independent activists in Beirut, the Biqaa and the Shuf. However contradictions soon started to surface, as radical groups argued that a more revolutionary movement was needed to continue the battle to bring down the whole system. Political parties from both 14 and 8 March also tried to hijack the movement and, finally, the revolt against the regime in Syria added a new problem: whether or not to support it? As the deadline for organising quadrennial legislative elections approached, controversies over the Electoral law stiffened, showing the underlying fragmentation and paralysis of the political class. Distrust and despair delegitimized the political arena.

The capacity for political mobilization and the long history of political engagement noticed by social scientists 4 seemed to have run out of steam after the national elections in 2009. In contrast, one could observe a steady increase in the voicing and actions of labour unions and civil society organisations in defence of labourers and employees, protesting against low salaries, unemployment, the lack of health coverage, the rising cost of basic commodities and the deterioration of working conditions. Beyond the negative effects of the deepening political crisis and financial uncertainty, social conditions have steadily deteriorated over the 2 For a reflection on authoritarianism in post-war Lebanon see Farid El-Khazen, 2003, "The Postwar Political Process: Authoritarianism by Diffusion", in T. Hanf, N. Salam (eds.), Lebanon in Limbo. Postwar Society and State in an Uncertain Regional Environment, Baden-Baden, Nomos Verlagsgesellschaft, p. 53-74.

3 Marie-Noëlle AbiYaghi, 2012, « Civil Mobilisation and Peace in Lebanon," http://www.cr.org/accord-article/civil-mobilisation-and-peace-lebanon accessed 25 January 2014. 4 Karam Karam, 2009 past half-decade while the Lebanese were enduring the consequences of the world economic crisis and the Arab Uprisings. 5 Therefore, social mobilisation, which had long remained contained by the confessional political leadership, hit the headlines in spite of the low level of unionisation. 6 In the early 2010s, "signs of life in various labour movements" suggested that "Lebanon's stillborn revolution" might lead up to a substitution of social mobilization for the aborted political struggle. 7 Electricity contract workers carried out the longest workers' uprising in Lebanon's modern history; public school teachers and the Union Coordination Committee representing teachers, professors, and public administration staff and retirees, led weeks of strike and protest; workers and employees in the Spinneys supermarkets announced the much publicised and widely supported creation of a new union; Beirut municipality employees, soon followed by their co-workers in Beiteddine and Tripoli, demonstrated in the streets; the bank employees' association took escalatory steps to bring the banks association to agree to renew their collective labour agreement, etc.8 Indeed labour and unionism issues became subjects of mass contest as in the other Arab Uprisings. [START_REF] Duboc | La question syndicale comme objet contestataire[END_REF] This trend could be noticed parallel to another one on the Lebanese scene: mobilizations in favour of foreign workers. While human rights associations proliferated in the wake of the civil war, 10 In Lebanon, dozens of such associations 11 are working along confessional charity NGOs such as Caritas in support of foreign workers, endeavouring to solve judicial and security issues, defend their rights and alleviate their harsh daily life. They are organised and powerful, make an intensive use of the Internet, and mobilize volunteers and local and international donors. An important novelty of the 2010s is that after long restricting their interest to (extremely ill-treated) female domestic workers 12 these NGOs and associations have become aware of the precarious situation of thousands of 'ummal wafidin 13 working in construction, agriculture and factories. Although the foreign workers may not play an active role themselves, the associations go public and voice complaints and demands that echo those of Lebanese workers.

In 2011, World Bank estimates put the total workforce in Lebanon at 1.2 million (for a population of around 4.2 million) of whom some 760,000 were foreigners (17.8 percent of the population, around 50 percent of the workforce). Direct observation and government statistics, however faulty they may be, 14

Breakdown of official foreign labour in Lebanon (excluding Syrian & Palestinian)

11 Lebanon Support, Daleel Madani. Civil Society Portal. See http://daleel-madani.org accessed 25 January 2014. 12 A choice, one of my interviewees argued, 'dictated by the feminists, Secretary of State Clinton and US funding.' 13 Arabic translation for foreign worker. 14 Studies on the workforce in Lebanon stress the difficulty of access to up to date, reliable and significant data on the recruitment and employment of foreign temporary workers (Sensenig-Dabbous, Hourani, op.cit. p. 2) mainly due to the inability/reluctance of the Lebanese state to publish useful statistics. Most of my interviewees and written sources suggested that official figures have to be multiplied by three in order to report the real number of foreign workers. According to unofficial estimates, the Ministry of Labour delivered 185,000 work permits in 2011 (this figure does not include permits for Palestinians or Syrians) -of which 45,000 were for non-domestic jobs. 15 Observation of these new trends in the context of diverse but significant Arab revolts led me to propose a hypothesis on the current mobilizations in Lebanon. In line with comments by specialists on migration in the Middle East who suggested that "there is a thread linking protest and international migration," 16 I proposed to make this thread visible and relevant to understand the new developments on the social scene in Lebanon. Namely, I noticed that the minister of Labour in the "8 March" Miqati government formed in June 2011, Charbel Nahas, put together a reform package to ensure the periodic adjustment of wages, to redistribute revenue from rentier to productive services, to reinvigorate the role of the unions and to create the basis for universal health care in Lebanon. Among other things, Nahas argued in favour of respecting international norms relating to the treatment of migrant workers. 17 He advocated extension of the minimum wage rule to foreign workers "not for humanitarian reasons but in order to boost the labour market." 18 Although new in Lebanon, such a discourse appeared to fit the "global legalist narrative" of equality, secularism and the rule of law developed by transnational forces in accordance with the policies of the great powers. Following the theory of migrations and trans-nationalism inspired by Wallerstein, 20 it is tempting to see the democratization discourse currently spreading over the Middle East impact on the integration of migrant workers in the receiving countries and boost transborder social networks. In the case of Lebanon, such promotion of democracy would result in empowering the migrants, especially the non-qualified migrants, and reducing the local competitiveness of their low salaries. My central hypothesis was that the social scene might witness a strategic bridging between Lebanese workers and their unions on the one hand, and foreign workers and their associations on the other in order to promote social measures to their common benefit. In other words, if there was to be a "revolution" in Lebanon, it would be primarily through the spill-over of a social movement across national boundaries, by means of the de-sectorisation of contentious politics and the concerted collective action of activists who, until then, have rarely cooperated in their struggle against economic and political domination. In view of the paralysis of the political sphere, and taking advantage of the "conjunctural fluidity of social relations," the unskilled Lebanese labourers and the exploited migrant workers would be able to jointly "mobilize their resources" beyond their conflictual sectoral goals in order to lead the country on the path of transition. 21 Reflecting upon these questions and examining the documentation collected during fieldwork led to three complementary tracks of analysis: the political economy of globalization without liberalization in countries such as Lebanon requires that the labour market remains split into competing segments; while workers from these various segments are stuck in a common no-win situation, agents all along the trans-boundary migratory 22 Michael Young, 1999, Migrant Workers in Lebanon, Beirut, The Lebanese NGO forum, http://www.lnf.org.lb/migrationnetwork/mig3.html accessed 25 January 2014. 23 Mary Kawar is an ILO researcher working on issues related to skills and employability, employment policy, youth employment and migration in the Arab East. Mary Kawar, Zafiris Tzannatos, 2012, "Private Sector Does not Demand Enough Skilled Labor", LCPS Policy Brief, http://www.lcpslebanon.org/publication.php?id=260 accessed 25 January 2014. networks cooperate to their mutual benefit. Therefore, social dynamics and power hierarchies have to be assessed on a transnational basis taking into account the strength of social networks; the changing ethnoscape and social dynamics within Lebanon's boundaries contribute to weaken the national narrative of the sovereign state if not its very existence.

Globalization without liberalization and the split labour market

Long before the neoliberalism of the Hariri era 24 Lebanon was the Middle Eastern paragon of a globalized merchant and financial economy. 25 Yet, before independence, and more than ever after the civil war, the globalization of the Lebanese "free-market" economy did not mean liberalization but rather the domination of powerful private interests. It did not imply the respect of fair competition and the rule of law by capital owners but rather their monopolization of wealth and the clientelization of the polity and society. 26 This monopolistic logic prevailed as far as immigration and labour rights were concerned.

The current situation of Lebanese legislation, carefully monitored by the ruling elite, is telling. The national strategy for inward migration remains extremely cautious and the regulatory frameworks dealing with migrant workers can be considered "poor and based on continuously changing policies." 27 As mentioned in note 15, Lebanon has not ratified the ILO conventions of 1949, 1955, the 1951 Geneva Convention and the 1990 convention on the Protection of the Rights of all Migrant Workers. Given the large influx of Palestinian refugees on its territory after the 1948-9 war, and given the unruly participation of hundreds of thousands of Syrian workers in its economy, it is understood that Lebanon will probably not ratify these instruments. 28 24 Hannes Baumann, 2012, "The 'new contractor bourgeoisie' in Lebanese politics: Hariri, Miqati and Faris" in A. Knudsen, M. Kerr (eds.), Lebanon after the Cedar Revolution, London: Hurst, pp. 125-44. 25 The resulting informality of the migrant work market fits into the general handling of labour issues in Lebanon. According to a 2011 World Bank report, "only 29 percent of Lebanese workers earn formal regular wages, the remainder being either informally employed, or selfemployed, or unemployed". [START_REF] Zbeeb | Bid farewell to a Lebanese Union impostor[END_REF] It is commonly agreed that this percentage is greater among the 60 percent of foreign workers, a large proportion of whom have entered Lebanon surreptitiously and illegally through the Syrian border or stayed in the country after expiration of their contract and visa.

Consequently, two main features characterize the foreign labour market in Lebanon: it is a split market, and an informal market organised/disorganised for the optimal exploitation of human work force.

Taking advantage of the participation of tens of thousands of skilled and unskilled Palestinian refugees in the 1950s and 1960s in a buoyant national economy while denying them the right to national integration (tawtin) provided an early model of disconnected policies for the business community's handling of foreign workers: "restrictions on the Palestinians' right to work lead to exploitative conditions but do not shut them out of the labour market." [START_REF]Palestinians in Lebanon working but under precarious conditions[END_REF] The Syrian exception in terms of labour legislation reinforced its segmentation. The Syrian pattern of migration and its relationship to the labour market and Lebanese society at large differs from those of other Arab migrants such as the Egyptians and Sudanese. Already in the 1970s, Syrian workers were more numerous than the Palestinians and easier to employ and dismiss. Affirming a long agreed bilateral policy (1949, 1972) renewed in the 1994 Labour Agreement (following the 1991 Treaty of Brotherhood, Cooperation, and Coordination), workers get a three month visa every time they show up at the border and are not required to have a work permit or a sponsor (kafil). However, the long political and military involvement of the Ba'thist regime in Lebanon during and after the civil war made, and still makes, their case politically sensitive. 31 Their number diminished drastically after the military withdrawal in 2005 but grew again dramatically when thousands of refugees fled their country in turmoil since 2011. 32 Beyond a hostile social discourse expressed across all confessional groups, they offer a ductile variation margin for the business community, not dissimilar to the role played by Pakistani Sunnis and Indian migrant workers in Gulf States such as Bahrain. 33 Following the Palestinian and Syrian patterns, national and even ethnic differentiation prevailed. The legal and factual differentiation between nationals and foreigners, Arabs and non-Arabs, and between various non-Arab nationalities was due to the employers' approach of splitting the market in order to take advantage of differences between native, unionized workers and undocumented immigrant, non-unionized workers from poorer countries. 34 In 1971 for example, Ittihad 'Ummal Balidiyyat Bayrut represented mainly southern Lebanese municipality toilers; in the immediate after-war Oger Liban carried on recruiting mainly Lebanese for the reconstruction and the street cleaning of downtown Beirut. However, progressively in the 1990s, Palestinian and Syrian manpower, then non-Arab migrants took over from Lebanese from the peripheral regions in these tasks and other unskilled jobs all over the country: in the construction sector and menial jobs in the agricultural and service sectors such as gas station attendants, janitors, cleaners, porters or sanitary workers, etc. 35 Year after year, capitalists and managers chose to recruit in foreign countries with lower standards of living in search of lower wage demands: Egyptians then Sudanese were "imported" in large numbers as well as Philippinos, then Sri Lankans and other Asians nationalities. 31 A decade later these unskilled jobs have become the almost exclusive preserve of Asian and African migrants. [START_REF] Dirani | Lubnani li-huquq al-'ummal wal-muwadhdhafin[END_REF] Field studies show ethnic and national specialisation of tasks by branch of activity and within firms, with specific nationalities restricted to specific occupations, [START_REF]Shiite foundation Mabarrat, the Lebanese are employed to deliver gas and Asians for car wash[END_REF] and the clustering of workers of same sex and same origin. [START_REF] Longuenesse | [END_REF] This allows employers to delegate the task of disciplining (in the Foucauldian sense) to the foreigners themselves, who enforce norms, statuses and hierarchies partly inspired by their milieu of origin. Besides facilitating social control, this strategy of splitting the labour market encourages a global downward spiralling of salaries on the national market, because Lebanese labour laws do not govern migrant workers' unskilled services: they rarely reach the minimum wage set by the law and are often not registered in the social security system. [START_REF]The Lebanese Salaire Minimum Interprofessionnel de Croissance[END_REF] For most migrants, the result of the segmentation of the labour market is the extreme insecurity and even destitution of a large majority of them. Only a skilled minority makes its way into the regular job market. Although studies are rare and most of them deal with the situation of domestic workers [START_REF] Moukarbel | Sri Lankan housemaids in Lebanon[END_REF] there is, as mentioned in the introduction to this chapter, a recent concern among burgeoning NGOs and in the civil confessional and trans-confessional society for the (il)legal treatment they undergo from state authorities (especially from the Ministries of Interior and Justice) and employers' organisations. Their lack of social and health protection, their often appalling housing conditions, their dreadful working conditions (ten hours a day, six days a week or more) and the meanness of their "salary" a part of which often remains in the hands of employers and middlemen are not new issues. [START_REF]A profile of sustainable human development in Lebanon, part III D[END_REF] However, they have only recently begun to draw public attention in relation to considerations on the meaning of democracy in Lebanon in comparison with neighbouring countries. In fact, media campaigns and festive demonstrations against xenophobia have mobilized a new generation of militants sharing a common alienation from Lebanon's traditional prejudices and political leadership. 42 Still, as underlined by all interviewees, nothing, or nearly nothing, of this has mobilized Lebanese labour unions. 43 Rather, the GCLW is "naturally" inclined towards protecting Lebanese workers against lower-priced migrant competition. 44 Union leaderships "advocate for the rights of the Lebanese workers before the government in order to regulate the flow of migrant workers and preserve them from the migrant labour competition." 45 They refuse to get involved in the support of foreign workers and the protest against their legally organised insecurity. 46 In return, less than 1 percent of non-Lebanese toilers join unions although they are legally entitled to become simple (i.e. non-voting non-eligible) members. 47 While the labour association was among the main actors of the political scene before 1975 when it enjoyed the support of powerful leftist parties, it is now shattered and weakened by a deadly sectarian competition. The GCLW went as far as ruling out the salary rises and other measures in favour of the working class proposed by Minister Nahas in 2012, in order to please its powerful political patrons, so fighting for the rights of migrant workers would be a far more remote objective. Yet, the exclusion of foreigners from the benefits of public welfare has several lopsided effects on the domestic labour market besides its harmful effects on the migrant market. It raises the domestic unemployment rate as it excludes from unskilled Lebanese workers from the labour market since they are not likely to accept the same terms as foreigners as they (unlike most foreign workers) have to pay rent and other expenses and want to be covered by social security. In the long run, the recourse to cheaper labour does not translate into tangible economic and social benefits for Lebanese citizens 42 Telling examples are the 2012 antidiscrimination internet campaign Shayef halek? ("Can you see yourself?") http://www.cheyef7alak.com/ accessed 25 January 2014 and the Jadaliyya video, 2012, Racism and segregation at the Lebanese beaches, http://www.jadaliyya.com/pages/index/6430/racism-and-segregation-at-lebanese-beaches-(video) accessed 25 January 2014. since their salary remains low while the employment of cheap foreign labour is not reflected in lower prices. 48 Tacit and active complicity in a "mafia-style" networking Migrant workers are the main losers in the current Lebanese process of deregulation of the labour market and the general paralysis of social movements, as confirmed by every study on their living conditions and net financial gains after reimbursing expenses for recruitment, travel, accommodation and sometimes residence and work permit. 49 Like the Lebanese workers and unions, but for other reasons, they are tacit participants in a global economy of labour substitution for the sake of entrepreneurs and managers. The threat of physical and symbolic violence plays a major role in their acquiescence as an overwhelming majority remains 'illegal' both in terms of residence and/or of work (an interviewee spoke of 75 percent of workers working illegally in the construction sector) and very frequently deprived of their passports, while unchecked xenophobic attacks make victims among them every week. Nevertheless, Asian and African foreign workers are more numerous every year in Lebanon where the economy of manpower importation is flourishing.

A full study of this economy would require minute concrete observations of the numerous agents involved in the process beyond critics of the modern world-system and humanitarian stances. As Mark Granovetter has observed, each of these agents takes part in a transnational network made of a "chain of small scale interactions." 50 Families, churches, unions and associations, local authorities and national officials, especially embassies, police and immigration service officials, employment agencies in the sending and receiving countries, brokers, travel agencies, smugglers, traffickers and even NGOs, not to mention the workers and employers themselves… each of them shares in the formation and operating of powerful transnational networks whose benefits s/he pursues for his/her own 48 UNDP 1997, part III D. 49 Most of the migrants finance their trip by raising resources through family sources, mortgaging/selling their property including house/land, taking loans at very high rates of interest or a combination of these. Seema Gaur, 2010, " Indian Labor Migrants in Lebanon: A Comparative Study of Migrants from Punjab and Tamil Nadu," Washington, D. C., The Middle East Institute, http://www.mei.edu/content/indian-labor-migrants-lebanon-comparative-study-migrants-punjaband-tamil-nadu accessed 25 January 2014. 50 Mark Granovetter, 1973, "The strength of weak ties," American Journal of Sociology 78 (6), pp. 1360-80. sake. 51 Informality and illegality are the key characteristics of the functioning of these transboundary networks that escape international regulation. In the case of Lebanon, they also escape loose national regulation because the state is fragmented, weak, and dominated by private interests.

A leading Lebanese political actor considers the system organising the inclusion of foreign workforce in the Lebanese economy as a "mafia-style network." 52 Indeed, what is occurring today in and around Lebanon fits the model discussed by Kyle and Koslowski: "Tacit and active complicity is required by a range of people in the sending and destination regions… Smugglers and traffickers … are deeply integrated into the social fabric of indigenous settings… and are facilitated by a loose network of recruiters, middlemen, actual smugglers, local and foreign financiers, and government officials and police…" 53 Following their hypotheses I will now discuss the three main features that characterize the foreign labour market in Lebanon: privatization, commodification, and de-territorialisation.

First, the logic of the free market imposes itself over any other consideration along the chain of migration and foreign employment, all the more so in Lebanon where traditional laissezfaire policies were further fostered in the 1990s and 2000s reconstruction period. Better known in the Gulf countries, the sponsorship (kafala) system governs the foreign worker market in Lebanon as well as in other Arab countries such as Syria, Jordan and Israel. It allows the externalization by the state of an important part of the control over the migrants in favour of employers and recruiters, and consequently "embodies the importance of private actors in migration management." 54 In the Lebanon of the 2010s, where political paralysis freezes the adoption of the yearly national budget and blocks decisions about structural reform there is hardly any national economic policy beyond the priority given to the banking and real estate sectors, even less an immigration policy beyond the rejection of Palestinian tawtin and the Syrian presence. Therefore, the decision to recruit foreign 51 N. M. Shah, 1995, "Emigration dynamics from and within South Asia," International Migration 33 (3/4), pp. 559-625. 52 « Un maillage mafieux », interview, March 2013. ILO officers disagreed with the formulation. 53 David Kyle, Rey Koslowski, 2011, "Introduction," in D. Kyle, R. Koslowski (eds.), Global human smuggling: Comparative perspectives, Baltimore, Johns Hopkins University Press, pp. 1-7. 54 Mehran Kamrava, Zahra Babar (eds.), 2011, Migrant Labour in the Gulf. Working group summary report, Doha, Center for International and Regional Studies, Georgetown University School of Foreign Service in Qatar, http://www12.georgetown.edu/sfs/qatar/cirs/migrantlaborsummaryreport.pdf accessed 25 January 2014. manpower in branches of activity such as agriculture, services and small industries does not depend on the existence of national manpower in these sectors nor does it respond to a national scheme to develop them. Rather, it depends on the comparative advantage offered by foreign toilers over nationals from the point of view of individual entrepreneurs.

Although national labour laws apply in principle to migrants also 55 the employer and/or broker (kafil) imposes all kinds of unfair terms of working conditions, wages and limits of mobility (end of contract; holding of passport …) on their foreign employees. He/she possibly avoids legal duties by outsourcing workforce i.e. turning to interim and importing agenciesthus gaining a comfortable margin of freedom and benefit; the same margin is withheld from his employees.

28 April 2013. Migrant workers rally in Beirut, demanding an end to the current sponsorship system in Lebanon (Photo Sabah Haider) 56 55 The Lebanese Labour code (1946, amended in 1993) applies to foreign workers except in agriculture and domestic employment. Foreign workers are entitled to receive health coverage during the period of their contract. 56 According to a Kafa official, abolishing the kafala system in Lebanon would help employers as well: "The relationship should be of an employer and an employee protected under labor law that ensures Inevitably, the privatization of the foreign labour market opens the way to informality and illegality in the status, activities, wages and movement of immigrants. [START_REF] Bret | Circulation transnationale et travail disqualifié au Moyen-Orient. Les travailleurs non-arabes au Liban[END_REF] Administrative controls are rare and hindered by powerful political bosses, and employers feel free to impose their terms on workers who mostly do not read Arabic and urgently need a salary. In return, a large proportion of imported workers quit their jobs before the end of their contracts in order to escape severe working conditions and heavy reimbursement charges.

Many stay in Lebanon and find another wild contract in another company or work free-lance as they cannot get hold on their passport until they reimburse their kafil. Also, in order to alleviate the payment of sojourn and work permits, import agencies (Lebanese makatib al-'amal) recruit unskilled immigrants for domestic or cleaning work and send them as full workers in remote industrial areas in the North or the Beqaa valley. [START_REF] Harb | head of the Textile and Leather branch in FENASOL[END_REF] As mentioned earlier, around two thirds of the foreign workers participating in the Lebanese economy work in the informal sector. The cost for individual workers in terms of health and retirement pensions is immeasurable. It is also heavy for the Lebanese state in terms of tax evasion. Besides, it raises issues of national security, since the Security Directorate lacks the means to monitor the composition and size of the current populations living in the country and the internal security forces and police are not prepared to guarantee their safety when they are confronted with deep racial prejudices. If one considers the logic of the government, and the security aspect of the management of the population, the question of who is a foreigner becomes primordial in the end. [START_REF]Taiwan as the Westphalian Society's Foucaldian Heterotopia[END_REF] It adds to the existing population segmentation and threatens the social pact between state and society. I will examine how this process of privatization affects the national identity of Lebanon In the third part.

Secondly, the Lebanese situation suggests that, rather being the result of negotiations and deals between migrant workers with their social capital, and local production managers with their economic rationale, migrant employment is a fluid and uncontrolled process. Myriads of "exogenous" key actors interfering at every juncture of the migration network are the decisive actors in international labour migration. [START_REF] Krissman | Sin Coyote Ni Patrón: Why the "Migrant Network" Fails to Explain International Migration[END_REF] These intermediaries of all sorts govern the migration network; they turn foreign manpower into a commodity and manpower import into a trade. They extract value from migrants as well as businessmen and share the profit of this commercialization between themselves. [START_REF] Shah | Emigration Dynamics from and within South Asia[END_REF] Private employment agencies may not be the most powerful agents along the network but they are certainly pivotal. While thousands of kilometres apart, recruiting offices in the sending country and placement offices in Lebanon can be considered "two sides of the same coin." 62 A main asset of their business is the bulk of information these agents master along the network and do not share with their "clients"-both employers and employees -in order to beguile them. 63 Here again migrant trade operates on the border of illegality either because legislation is complex (for example migrant workers who wish to regularize their residence situation by paying taxes to the Ministry of Interior cannot do so without jeopardizing their current situation); or it is incomplete (as neither minimum wage nor social security apply to foreigners according to Lebanese law); or because the authorities are unable/unwilling to enforce it: for example, migrant workers arriving in Lebanon see their passport confiscated by their kafil, although this discriminatory measure has been repeatedly condemned by the UN and fought by local human rights lawyers. [START_REF] Shahinian | UN Special Rapporteur on contemporary forms of slavery[END_REF] The role played by political and social (sectarian and family) elites in enforcing, overseeing and cashing in on the foreign labour trade fits well with the traditional political economy of the "Merchant Republic." Until today, there has been no systematic study of the "collusive transactions" 65 linking political leaders to the business elite in order to facilitate the exploitation of foreign manpower at lowest cost. Yet, many observers agree that what they denounce in the domestic labour field as exploitation also takes place in the imported labour market, only in worse conditions. Sectarian and political leaders use their positions as lawmakers to facilitate administrative arrangements in favour of their business partners or for their own sake. 66 The burying of Minister of Labour Boutros Harb's proposed legislation 67 in the parliamentary sands and the rejection of Minister of Labour Charbel Nahas' aforementioned reform by Najib Miqati's government are telling examples. The rationale behind such tactics is to raise entrepreneurs' immediate profits in spite of the fact that "the reduction of production costs by employing cheap unskilled unmotivated manpower locks the structure of the economy into low productivity, low value-added jobs and low wages." 68 While agencies and political leaders play a leading role in the labour trade, making profit by selling foreign manpower is tempting for every actor along the migration network in a context of neoliberal globalization, even for the migrant workers themselves. Obviously, in the short term, many migrant workers appreciate their freedom from monthly taxes and social security contributions, and are therefore prepared to choose illegal networks. 69 Here, the hiding or distortion of useful information by network operators plays a decisive role. A comparative study of Tamil and Punjabi workers in Lebanon showed that the former were mostly brought in by agencies on legal visas and were employed in the organized sector.

While they were deprived of part of their wages, they migrated in relatively secure conditions. For their part many Punjabis had their migration arranged through a close family member already living in Lebanon. While such arrangement seemed to guarantee savings and security, early immigrants actually played the role of agents, obtaining sponsorship and 65 Dobry, op. cit. p. 110. 66 The struggle of Spinneys supermarkets' employees against their manager in 2012 revealed that sectarian leaders from various regions had ownership of the land where the retailer's branches were installed. Only a small minority of foreign workers was involved in the struggle, and there was hardly a mention of their particular fate in the press. See the reports in al-Akhbar from August 2012 to January 2013. Also Elisabeth Longuenesse and Paul Tabar's unpublished field work (2013) shows that local political forces are able to impose quotas of national and sectarian groups in neighbouring factories. 67 Marlin Dick, 11 February 2011, "Harb drafts laws to protect domestic workers", The Daily Star. 68 Kawar, Tzannatos, op. cit. pp. 6-7. 69 According to IDAL (Investment Development Authority), employees' contribution should be 2 percent of their monthly wage. work permits from local employers and selling them to prospective migrants in the name of family and friendship ties. 70 In the end, if the Punjabis did better in Lebanon than the Tamils, it was thanks to the higher social capital that they had acquired before their departure from India. Their living conditions and financial gains were not improved, in fact the reverse, by their use of informal migration channels. This leads to the third characteristic of the foreign labour market in Lebanon: The political economy of foreign employment has become de-territorialised, that is, operated by transboundary actors and regulated by transnational networks. While this is a common characteristic of unskilled labour migration around the world, the process has been facilitated in Lebanon over the last thirty years. Non-Arab Asian migrants entering Lebanon were able to by-pass state sovereignty thanks to the 'special relation' linking Lebanon to Syria. Moreover, in the recent period, migration agents also made extensive use of the internet to organise and protect their businesses. Both the recourse to a neighbour's soil and dealing through the Internet are indications of the de-territorialisation of the labour migration process. Among illegal foreign workers, a telling number have entered Lebanon by crossing the land border between Syria and Lebanon. 71 Indeed traffickers in manpower were able to fly workers into Syria, since governments such as India had good relations and favourable customs agreements with the Ba'thist regime, allowing employment agencies to open branches in Damascus. Only on their arrival at Mezzeh airport would newcomers understand that Syria was not the end of their journey even when the company supposed to hire them had Syrian headquarters. This meant that many Asian migrants purchased their visas for Syria and most of their journey remained within a legal framework. Still, for the last part of their journey, they had to walk across the Syrian Lebanese border, led by local smugglers who relieved them of their last dollars and sometimes of their passports. Unlike the Syrian workers who were free to cross back and forth over the border under the condition of paying public taxes and private fees, Asian (and African) migrants entered the land of 70 Gaur, op. cit. p. 6. 71 This information is available in global studies (Young; Sensenig-Dabbous, Hourani) and was confirmed by an anonymous employee in Caritas interviewed in Jisr el-Basha on 14 March 2013. illegality where they remained trapped until they became able to reimburse months and years of sojourn permit and the price of their passage.

It is necessary to point out that labour smugglers are generally far from the outlaws and other kinds of bandits imagined by state employees and international experts in distant offices. Before the Syrian uprising of 2011, passage across the Syrian Lebanese border was sponsored by Syrian and Lebanese top political leaders and military officers, and controlled by police and customs administrations from both states that taxed them on their way, as testified in most victims' narratives. In addition, it was not until relatively recently that most South Asian states had functioning embassies in Lebanon, with sections to care for expatriates' interests. Local "honorary consuls" were said to attend to their own financial business-even by participating in the immigration racket -rather than to the interests of the nation they were supposed to represent. 72 Even now, these embassies do not have the concrete means to check the delivery of work permits and migration movements of their nationals in Lebanon. 73 Finally, the de-territorialisation of labour migration does not consist only of the capacity of trans-boundary actors to get around the rules and legal power on the ground. Increasingly, it consists of a dematerialisation of the migration network through electronic communication and the negotiating and striking of deals whose participants are as efficient as they are inaccessible. Typing "Asian workers for Lebanon" in to a web search engine leads to buoyant e-commerce websites with suggestive names, administered in China, Malaysia or elsewhere.

Tens of companies often splintered between "mother" and "franchise" branches all over the Middle East and South Asia declare their business as "staffing for the construction and oil and gas industry" and "providing skilled and non-skilled workers along with caravans and their tools." Contacted by phone (their physical address was impossible to locate) "legal representatives" of employment agencies in Beirut were eager to promote themselves as graduates of Business departments at obscure American universities. They were willing to discuss deals such as "providing 40 unskilled Nepalese for a cleaning enterprise in Beirut" but soon retracted when understanding my inquiry was only academic. Although limited, my probe into such a complex network suggests that transnational networks dealing with human labour are at the forefront of aggressive financial capitalism.

On the future of Lebanon's identity and sovereignty

Besides the steadily growing labour immigration discussed in this chapter, Lebanon is experiencing an important emigration, especially of skilled manpower, which grew rather than decreased after the ceasefire in 1990. Experts estimate that more than half a million people emigrated from Lebanon between 1975 and 1995. [START_REF] Hamdane | Assurer du travail pour le retour des personnes qualifiées[END_REF] 40 percent of this emigration consisted of highly qualified young people, [START_REF] Jouni | La migration hautement qualifiée au Liban[END_REF] as the rate of unemployment increased during the so-called reconstruction period, especially the unemployment of skilled workers, making universities a mere "export industry." [START_REF]National survey of household living conditions 2004-5[END_REF] Mary Kawar comments on this trend by showing that "specific factors contributing to a low level of labour demand and skills include macroeconomic uncertainty, poor governance, corruption, and weak public infrastructure," thus locking the private sector "in a low productivity and low-wage equilibrium." [START_REF] Kawar | Specific factors contributing to a low level of labor demand and skills include macroeconomic uncertainty, poor governance, corruption, and weak public infrastructure[END_REF] To this day, the migration deficit of Lebanon has remained understated because the balance of remittances has stayed positive: Remittances from Lebanese abroad amounted to $7.2 billion in 2009 (20 percent of GDP) while outward remittances flows were estimated at $5.7 billion (17 percent of GDP). 78 Still, the human dimension is striking: the World Bank put the stock of emigrants at 664.1 thousands (15.6 percent of the population) for 2010 and the stock of immigrants at 758.2 thousands (17.8 percent). 79 Lebanon therefore became a labour surplus economy at both ends; the duality in its workforce "consists on the one hand, of highly skilled job seekers who often emigrate and, on the other hand, of low-skilled job seekers who usually remain in the country and are employed at low wages." 80 An interesting and rarely noticed point in Kawar's remarks concerns the changing identity of the workforce and the labour market in general. It is not only that foreign immigration overtook national emigration in the recent years. Kawar writes that "*migrant+ low-skilled job seekers (…) usually remain in the country," thus inducing a steady and significant change in the sociological composition of the local population. In Beirut as in Hong-Kong and in other big buoyant cities of Asia, foreign migrants have gained visibility in the public space, especially on Sundays when local families remain at home and socialise privately. In suburban districts such as Dora in Beirut it is common to see migrants out and about. Here, banks, restaurants and cafés, food markets, shopping malls, medical and social centres connect them to their fellow nationals and their home countries. At the same time they transform the urban landscape and reveal themselves as real and visible inhabitants of Lebanon. Assaf Dahdah's fine anthropological study of non-Arab women migrants in Greater Beirut 81 shows how "in the context of high segregation and fragmentation that characterizes Beirut, *these migrants+ contribute in the interstices of the legality and of the city to its 'recreation' as a new figure of 'citadinity'". In the district where these migrants invent new forms of public space, local and global stakes interweave in a process of "glocalisation" and contribute at the same time to shape new Lebanese national stakes. Indeed, identity tensions mixed with class tensions have grown along the visibility of foreign workers. The reverse face of the process of re-cosmopolitization of Beirut 82 is the spreading of xenophobic reactions and racist crimes that strike Syrians in particular but do not spare newcomers from Asia and Africa. Parallel with the splitting of the labour market, one can observe the spatial and social segmentation of the society, building an invisible barrier between the Lebanese and other inhabitants of Lebanon. As underlined by a majority of my interviewees, only new NGOs acting under the influence of sister-bodies in the politically 80 correct international civil society mobilize against exploitation and racism. True, they are more active on the Internet than on the ground. The state for its part remains inactive as it is dominated by powerful networks of interests that take advantage of the situation. As for workers' unions and leftist parties such as the LCP that should include migrants' rights in their current protest movement-if only for the sake of their own members-they have failed to overcome the dominant popular feeling that foreign workers are a threat to the domestic labour market. Like the state, they remain trapped in corporatist segmented mobilizations imposed by confessional leaders and business interests.

In spring 2013, growing tensions in Lebanese political life brought the government to a standstill after Najib Miqati's resignation (25 March 2013) and exposed the hollowness of the upcoming general election. The damaging effects of the military spill-over of the Syrian crisis in the Lebanese arena function as a self-fulfilling prophecy as Salafis and Hezbollahis engage deeper every day in support of each of the Syrian fighting camps. This dangerous drift cannot but convince public opinion of the failure of the official policy of "dissociation" promoted by President Sleiman. 83 For all varieties of Lebanese, Syria remains the key to all evils or solutions in Lebanon eight years after its military withdrawal. There are few observers and leaders who dare to acknowledge that the reason why the Syrian crisis exposes and shakes Lebanon more than other neighbouring countries such as Jordan and Turkey is to be found in Lebanon itself. Indeed, as this study has showed, Lebanon's vulnerability has to be understood in terms of domestic as much as external factors. It is related to the steady but hardly noticed change in the identity of its society and polity during the past decades, especially after the end of the wars between 1975 and 1990 when migration issues increasingly transformed economic trends, social stakes and finally the national political order.

On the issues of employment, the reining in of foreign manpower and dealing with foreign workers, the Syrian crisis is crucial-probably more crucial than the situation of the Palestinian refugees. Indeed the crossing of the border by Syrian businesses and financiers in 83 International Crisis Group, Report 141, 13 May 2013, "Too Close for Comfort: Syrians in Lebanon", p. 30.

  the Syrian withdrawal in 2005 gave them a new boost, especially for advocacy groups such as Ruwwad (2004) which cares for imprisoned refugees and illegal migrants, Kafa (2005) which opened a branch devoted to migrant workers in 2010, or al-Mufakkira al-Qanuniyya ("the Legal Agenda") founded in 2009 by the well-known lawyer Nizar Saghiyeh.

  and rough comparisons between figures from the Central Administration of Statistics for 1998 quoted by Young (p. 6) and the 2010 estimate by the Pastoral Care of Afro-Asian Migrant Workers (PCAAM) quoted in the 2011 CARIM Report, 15 all show a sharp increase in foreign manpower, and a particular growth in Asian labour immigration as well as a new and important African immigration in contrast to the global decrease of Arab manpower.

Field

  research to test this hypothesis was conducted during two fifteen days visits in Lebanon, in November 2012 and March 2013. I interviewed stakeholders such as union members and leaders in GCLW (General Confederation of Lebanese Workers) and FENASOL (Federation of Workers and Employees Unions in Lebanon, a split from GCLW), government authorities in the Security Directorate and an ex-minister of Labour. I met ILO (International Labour Organization) specialists such as Azfar Khan and Mustafa Said. I visited civil society organisations devoted to the support of migrant workers: Frontiers (Ruwwad), Lebanese Labour Watch (al-Marsad al-Lubnani li-Huquq al-'Ummal wal-Muwadhdhafin), Arcenciel and Caritas-Lebanon. I corresponded with executives in labour import companies and members of the AliBaba network. I discussed with analysts such as Elisabeth Longuenesse (IFPO), Paul 20 Stephen Castles, Mark Miller, 2003, The Age of Migration: International Population Movements in the Modern World, New York, The Guilford Press. Castles' hypotheses have been deconstructed for the Gulf monarchies by Claire Beaugrand, 2010, "Politiques de non-intégration dans les monarchies du Golfe. Discuter les raisons de leur pérennité," Transcontinentales 8/9, http://transcontinentales.revues.org/793 accessed 25 January 2014. 21 Michel Dobry, 1986, Sociologie des crises politiques. La dynamique des mobilisations multisectorielles, Paris, Presses de la Fondation Nationale des Sciences Politiques. Tabar, director of LAU (Lebanese American University) Institute of Migration Studies, Assaf Dahdah, a PhD student in anthropology at Université de Provence and Karam Karam (Common Space Initiative for Share Knowledge and Consensus Building) I was given the opportunity to present my preliminary hypothesis in a seminar at IFPO (3 November 2012). Participants unanimously stressed that no real de-sectorisation was taking place in Lebanon, although the rise in activism and protest I had noticed was beyond question. While they did not dismiss the possibility that social mobilisation could successfully substitute for political activism in the current deadlock, they concurred in doubting whether it would be possible to build a bridge between national and foreign claims, and establish cooperation between the two labour sectors. Contacts, interviews and readings, namely of Michael Young's report 22 and Mary Kawar's studies, 23 only confirmed these early answers. The second seminar on Foreign Workers in Lebanon organised by Elisabeth Longuenesse at IFPO (20 March 2013) brought further confirmation with additional comments and elements of comprehension. Yet, my curiosity remained and my early hypothesis morphed into a new series of questions: which elements, which dynamics and conditions explain the current situation of the labour market in Lebanon and the endurance of the boundaries between the various categories of exploited labour? Should we look into the Lebanese polity or into transnational labour networks to understand the current situation? How do the national and the international dimensions meet and connect, around which crucial matters, through the mediation of which actors? And what could be the consequences of such structure for migrant workers in Lebanon and for the Lebanese social fabric?

  43 I was told of an attempt by the Progressive Socialist Party (led by Druze chief Walid Junblatt) to raise the issue; of a failed joint mobilization of Lebanese drivers and foreign cleaners at Sukleen in downtown Beirut during Muhammad Fneish's ministry (July 2008 -Nov 2009); and of a recent joint strike in an Ouza'i factory.44 Young, p. 52. 45 Sensenig-Dabbous, Hourani, op.cit. p. 40. 46 Ahmad Dirani, 10 March 2013. 47 Youssef Harb, head of the Textile and Leather branch in FENASOL, interview, 14 March 2013.

  , "An Analysis of Political Change in Lebanon in the Light of Recent Mobilization Cycles", in Laura Guazzone, Daniela Pioppi (eds.), The Arab State and Neo-liberal Globalization. The Restructuring of State Power in the Middle East, Reading, Ithaca Press, pp. 47-73.

  Martin J. Mc Dermott, 2010, Report of the Committee on Pastoral Care of Afro-Asian Migrant (PCAAM) workers in Lebanon to its president Bishop Elias Nassar, quoted in Sensenig, Hourani, p. 39.

19 16 Philippe Fargues, 2011, "Voice after Exit: Revolution and Migration in the Arab World

	", Migration
	Information Source, http://www.migrationinformation.org/Feature/display.cfm?ID=839 accessed 25
	January 2014. Before discussing Arab emigration toward Europe, Fargues mentions migration
	processes in the Arab lands generally.
	17 Intervention in a closed seminar on migrant labour, Institut Français du Proche-Orient, 3 November
	2012. The Lebanese authorities have been reluctant to ratify international agreements on migrant
	workers such as the ILO conventions of 1949 and 1955, and the 1990 Convention on the Protection
	of the Rights of all Migrant workers and members of their Families. Eugene Sensenig-Dabbous, Guita
	Hourani, 2011, "Towards Effective Temporary Labor Migration Schemes Report on Lebanon and
	Jordan", CARIM (Consortium for Applied Research on International Migration) Research Report 2001-
	08, http://hdl.handle.net/1814/19882 accessed 25 January 2014.
	18 Azfar Khan, senior migration specialist, International Labour Organization, Regional Office for Arab
	States, Beirut. Interview, 9 November 2012.
	19 David Mednicoff, 2012, "The Legal Regulation of Migrant Workers, Politics and Identity in Qatar
	and the UAE", in Mehran Kamrava, Zahra Babar (eds.), Migrant Labor in the Persian Gulf, New-York,
	Columbia/Hurst, pp.187-215.

  Carolyn Gates, 1998, The Merchant Republic of Lebanon: Rise of a Open Economy, London, I. B. Tauris. 26 Reinoud Leenders, 2012, Spoils of Truce: Corruption and State Building in Post-war Lebanon, Ithaca, Cornell University Press. 27 The key governmental agencies managing the issue of migrant labour are the general security in the Ministry of Interior, the Ministry of Labour and the Ministry of Social Affairs. Sensenig-Dabbous, Hourani, 2011, op. cit., II.A. Lebanese Government Level, pp. 30-4. 28 Lebanon currently excludes signing ILO conventions C118 on Equality of Treatment of Nationals and non-Nationals in Social Security, C97 on Migration for Employment and C143 on Migrations in Abusive Conditions and the Promotion of Equality of Opportunity and Treatment of Migrant Workers. Yet, it ratified the Palermo Protocol to Prevent, Suppress and Punish Trafficking in Persons,

  John Chalcraft, 2009, The Invisible cage. Syrian Migrant Workers in Lebanon, Stanford, Stanford University Press. 32 "Anti-Syrian tide drives workers out of Lebanon," The New York Times, March 4, 2005 ; Immigration and Refugee Board of Canada, 2009, Lebanon and Syria: Situation of Syrians in Lebanon; violence against Syrians; political affiliation of Syrians; naturalization of Syrians in 1994 (1994-2009), ZZZ103296.E, http://www.refworld.org/docid/4b7cee9023.html accessed 25 January 2014; Fabrice Balanche, "al-'Ummal al-Suriyyun fi Lubnan, Le Monde Diplomatique Arabic Edition, March 2007; Ahmed Mohsen, "Syrian Workers Eyed with Suspicion after Uprising," al-Akhbar English version, 5 December 2011. 33 Laurence Louër, 2008, "The political impact of labour migration in Bahrain," City & Society 20 (1), pp. 32-53, 34 Edna Bonacich, 1972, « A theory of ethnic antagonism: the split labor market », American Sociological Review 37 (5), pp. 547-59. I thank Dr. Louër for directing me to this reference during our fruitful discussion in October 2012.

35

Young, op. cit. 1999, p. 4.

  Kawar, Tzannatos, op. cit. p. 4. 81 Assaf Dahdah, 2012, L'Art du faible. Les migrantes non arabes dans le Grand Beyrouth (Liban), Beirut, Presses de l'IFPO. For an English abstract see http://www.ifporient.org/node/1169 accessed 25 January 2014. 82 For a comparable example see William Berthomière, 2005, "The emergence of a cosmopolitan Tel Aviv," Migracijske i Etničke Teme 21, pp. 243-53, http://halshs.archives-ouvertes.fr/halshs-00573832/ accessed 25 January 2014.

With a national debt up to 58 MM$, no government budget approved since 2006 and a slowing down of growth from 5% to 1.5% in 2012. See http://www.lcpslebanon.org/publications/1345209118-economic_challenges.pdf accessed 25 January 2014.

 6 Only 5 percent of employees and workers adhere to a union according to Mohammad Zbeeb, 28 December 2012, "Bid Farewell to a Lebanese Union Impostor", al-Akhbar English

edition.7 Rasha Abouzaki, 18 July 2012, "Lebanon's stillborn Revolution," al-Akhbar

English edition.8 These are the most publicised social mobilisation documented and discussed in the daily al-Akhbar since April 2012 by journalists from the economic and social desk Rasha Abouzaki, Hassan Chakrani, Faten Elhajj, Mouhamad Wehbe, Mohammad Zbeeb and others.

For example, the Philippines, Sri Lanka and Ethiopia briefly forbade labour expatriation to Lebanon when they took direct charge of their interests in Beirut. For details see Young, op.cit., pp.16-8.

This led one of our interviewees to denounce the complicit and corrupt role paid by diplomats from the sending countries. Beirut, 20 March 2013.

the wake of the 1963 Ba'thist coup, [START_REF] Picard | Managing identities among expatriate businessmen across the Syrian-Lebanese boundary[END_REF] the massive and unruly participation of Syrian unskilled workers in national production since the 1990s, [START_REF] Chalcraft | [END_REF] and the recent arrival of several hundred thousand Syrian refugees in Lebanon fed negative representations, impacted the strategies of economic actors and shaped state policy toward immigration. In this respect, the tense relation between Lebanese and Syrian workers on the labour market offers a dominant pattern for the treatment reserved for migrants of other origins notwithstanding the fact that their numbers and needs make the Syrians threatening competitors in a depressed labour market.

Beyond renewing the social question in Lebanon, the migrant phenomenon contributes to the renewal of the national question because "immigration constitutes the limit of what constitutes the national state… Immigration *…+ reveals in broad light the hidden truth and the deepest foundations of the social and political order we describe as national." [START_REF] Sayad | Immigration and 'State Thought[END_REF] A study of this question in Lebanon is beyond the scope of this chapter on migrant labour, workers' mobilization and their failed cooperation. Yet a cluster of legal debates concerning the acquisition of Lebanese citizenship (to descendants of emigrants, to children of Lebanese women married to foreigners …) and political controversies on naturalization-especially after the 1994 decree [START_REF] Hourani | The 1994 Naturalisation decree[END_REF] -underlines a slow but deep change in the composition of the population living in the country. The often-discussed confessional dimension in this change (namely the diminishing role of the Christian communities) combines with a crude socioeconomic dimension (the issue of poverty [START_REF] Laithy | Poverty, Growth and Income Distribution in Lebanon[END_REF] ) which the Lebanese authorities often prefer to acknowledge in terms of ethnicity (Arab vs. non-Arabs). They nurture the illusion of the temporary sojourn of migrants (and the future return of émigrés) in order to justify discriminatory policies of non-integration. Their short-sightedness conveys a defensive awareness of national identity because in Lebanon, as in the Gulf countries, "the migrants are the foil in relation to which the nationals perceive and define themselves." 89 Growingly concerned with their future, Lebanese workers use migrants as scapegoats rather than allies in their struggle against elusive trade networks. 89 Anh Nga Longva, op.cit. p. 184.