Jesús González Feliu
email: jesus.gonzales-feliu@let.ish-lyon.cnrs.fr

Traffic and CO 2 emissions of urban goods deliveries under contrasted scenarios of retail location and distribution

This communication presents four contrasted and near-caricatured scenarios of retail location and distribution, and compares them on the bases of both road occupancy rates and greenhouse gas emissions. Two main families of scenarios are defined: retailing land-use scenarios, based on the location of the different retailing activities of a city, and end-consumer delivery organisational scenarios, based on the definition of new services to deliver end-consumers, at home or to reception points. Those scenarios are simulated using an integrated approach combining inter-establishement goods transport flows, shopping trips and end-consumer deliveries. The simulation approach is able to show the relation between several aspects of retailing deployment (store location, catchment area's supply, urban retailing planning policies) and both upstream distribution of goods to retailers and downstream usage of private vehicles for shopping. Although scenarios are extreme and nearcaricatured, they are able to identify the limits and forces of the different retailing strategies in urban zones.

Introduction

City logistics aims to study the urban part of the logistic chain and more precisely freight movements (in their different form) in order to reduce costs, externalities and nuisances related to urban goods transport. Several methods and approaches are found in literature [START_REF] Taniguchi | City Logistics. Network modelling and intelligent transport systems[END_REF]van Binsbergen and Visser, 2002;[START_REF] Anderson | Urban logistics--how can it meet policy makers' sustainability objectives?[END_REF][START_REF] Ambrosini | Urban freight modeling: a review[END_REF]Craninc, 2008;[START_REF] Gonzalez-Feliu | Models and Methods for the City Logistics -The Two-echelon Capacitated Vehicle Routing Problem[END_REF][START_REF] Quak | Sustainability of urban freight transport: Retail distribution and local regulations in cities[END_REF]. However, most works focus on final deliveries to retailers, and not on the other part of the urban supply chain, that of endconsumer movements [START_REF] Russo | Demand models for city logistics : a state of the art and a proposed integrated system[END_REF]Gonzalez-Feliu et al., 2010). Three main types of flows can be related to goods transport in urban areas (Ségalou et al., 2006): interestablishments movements (IEM) are related to freight distribution between the different activities, i.e. the exchange of goods between establishments; end-consumer movements (ECM) can be defined as the trips where the purchased goods are transporter near the consumer's location, and urban management movements (UMM) include all flows related to the logistics activities of the city and its infrastructures (waste management, building, road and network construction and maintenance, postal services, household and enterprise moving actions, etc.). The first group of urban freight movements has been one of the most studied subjects in city logistics research. The second group, commonly studied in other fields but often not modelled as a part of the global urban freight distribution chain, is however an important component in terms of traffic volumes. According to [START_REF] Gonzalez-Feliu | Estimating traffic flows and environmental effects of urban commercial supply in global city logistics decision support[END_REF], shopping trips represent in France between 10% and 25% of the total person trips, depending on the day of the week, and almost half of the total rad occupancy issues (in km.PCUs, i.e. Private Car Units) of urban goods transport flows. In terms of pollution, the urban transport of goods, including end-consumer movements, produces about 25% of the total CO 2 emissions for transport, 35% of the NO x emissions and 40 to 50% of the solid particles [START_REF] Segalou | The environmental assessment of urban goods movement[END_REF].

Moreover, shopping trip behaviour is directly related to retailing land-use policies and to new services to consumers, like e-commerce and proximity delivery distribution services.

Furthermore, those actions have also a direct impact on deliveries to retailing activities, showing that the link between IEM and ECM is crucial in urban logistics. It is then important to estimate the impacts of such policies and actions on the overall urban goods transport system, i.e. that which combines IEM, ECM and UMM flows. However, UMM being indirectly related to the other two flows, can be studied in a second time.

The aim of this paper is to propose and examine four extreme scenarios and estimate the impacts of the actions they represent on both road traffic flows (in terms of rad occupancy issues) and greenhouse gas emissions. First, the simulation methodology used to estimate the impacts of the scenarios on urban goods flows is presented. Second, the proposed scenarios are described. Third, the four scenarios are simulated and the results compared and discussed. Finally, as a conclusion, the main strengths and limits of the analysis are presented, as well as further developments.

Freight transport flow estimation: a global approach

As shown above, urban goods transport includes three categories of flows (Ségalou et al., é006):

• Inter-establishment movements (IEM), which includes freight distribution deliveries and pickup trips, for all economic activities of the urban area. So, not only the retailing distribution is concerned by IEM, but all pickup and delivery operations related to commercial activities and its related transport flows. According to Ségalou et al. (2004), they represent about 40% of the total road occupancy issues of urban goods transport.

• End-consumer movements (ECM) are nowadays mainly purchasing trips by car, but with the development of new practices, like home deliveries, e-grocery, direct circuit B2C services, pickup points development, etc., they will soon include a variety of flows and can sometimes substitute IEM flows in the terminal part of supply chains.

They represent about 50% of road occupancy issues (Ségalou et al., 2004) • Urban management movements (UMM) are those related to all logistics activities of the city that are not necessarily related to commercial activities or that are linked to the development and maintenance of the city. The main flows are those of building, road and network maintenance activities, followed by waste collection, management and recycling activities. Other flows concern household and enterprise moving actions, postal services (both official and informal), representation activities and reparation services to private or professional customers, among others. By subtraction, all those flows represent about 10% of the total urban goods transport movements, in road occupancy issues.

Moreover, the sum of those three types of flows (so the total urban goods transport flows) represent about 20% of the total road occupancy Km.PCU and 25% of greenhouse gas emissions (Ségalou et al., 2004).

As seen above, IEM and ECM represent about 90% of the total urban goods transport flows and about 18% of the total urban transport flows. They are of different nature (IEM are mainly trucks of 3.5T or more, whereas most ECM are nowadays trips of inhabitants by private car), but they share the same space (urban roads and streets) for both running and parking. It is then important to combine them in a unique model to simulate the impacts of urban logistics planning actions, as shown in [START_REF] Russo | Demand models for city logistics : a state of the art and a proposed integrated system[END_REF]. However, current works remain conceptual, with few real applications. For that reason, we have recently proposed an approach to include ECM into existing IEM frameworks (Gonzalez-Feliu et al., 2010). We present here the integration of both tools (an IEM and an ECM model), as the continuation of the work presented in Gonzalez-Feliu et al.

(2009a).

The integrated framework is then composed of two modules, one for IEM simulation (FRETURB) and one for ECM simulation (STG).

FRETURB is data production and diagnosis framework for decision support in urban freight

distribution that presents different functionalities (Gérardin [START_REF] Conseil | Diagnostic du Transport de marchandises en ville dans une agglomération[END_REF]. It is able to estimate the IEM demand for a given urban area. Then, it can estimate road occupancy rates by running vehicles. More information is given in Gérardin Conseil et [START_REF] Conseil | Diagnostic du Transport de marchandises en ville dans une agglomération[END_REF] and in [START_REF] Ambrosini | Urban freight modeling: a review[END_REF]. The model has been calibrated from logistic behaviours observation, for several surveys in the late 1990's [START_REF] Ambrosini | Urban freight modeling: a review[END_REF]. Organisation and management of the logistic chains have been analysed according to a large typology of establishments (116 types according to the nature of their activity and their size).

The STG framework is a new shopping trip estimation model built from the following definition of private car shopping trips: for each purchasing activity, two related trips are defined, one ending at the shopping activity and the other starting at it. First of all, the demand is estimated considering that the shopping destination is chosen according to the commercial zone attractiveness, which depends on the commercial supply, the type of purchase and the available modal choices (Gonzalez-Feliu et al., 2010a). The novelty here is that the trip distribution is not made using a classical trip estimation method (like in

Proposed scenarios and computational experiments

In order to analyse the impacts of different planning or management actions on urban goods transport flows, we propose to simulate four constrasted extreme scenarios. Those scenarios result from the generalization of current practices in retailing and although their deployment as on the proposed scenarios is unrealistic they represent the limits of the four actions proposed. For that reason, we think it is important to simulate and analyse them. The scenarios can be grouped into two families.

The firs family represent the action of public authorities on retailing land use. They are then two cases of pushing the deployment of different forms of retailers to the extreme. They are obtained from data extracted from the French Surveys on Urban Goods Transport and defined via conversion tables (Gonzalez-Feliu et al., 2009b). In scenario 1, we assume that all retailing activities are concentrated in 15 big peripheral commercial centres. The urban forms associated to those commercial centres are agglomerated retailing areas containing hypermarkets and supermarkets with a gallery of complementary small retailing activities.

Inhabitants need then to reach those zones to make their purchasing activities, mainly by car.

In scenario 2, only proximity retailers are allowed in the city. No hypermarkets or supermarkets are defined, but a wide variety of small stores and complementary retailing activities, spread in the territory at the pro-rata of the population.

The second family represents the development (in extreme situations) of different proximity delivery services already proposed by different retailing activities. To estimate them, we use the ratios of Alligier (2007), who determined the main characteristics of home delivery routes in France. Then, we suppose 15 distribution depots, instead of current hypermarkets and big surfaces. From those points, that act as intermediary logistics platforms, two main strategies to deliver the households are possible. In scenario 3, all households are directly delivered by the principle of current household deliveries. In scenario 4, a spread network of reception points were people can take their commands. Those reception points are located at the prorate of the population.

For each scenario, only one type of household supply strategy is allowed (in scenario 1 supermarkets, in scenario 2 proximity retailers, in scenario 3 home deliveries and in scenario 4 proximity reception points.

Results and discussion

The proposed scenarios are simulated using the presented method. We also simulate a reference situation, that of Lyon in 2006. For IEM we take into account only the last transport flows (i.e. the direct deliveries to retailing activities, which represent about 20% of IEM). We report the results in Table 1 All proximity stores +90% -87% -63% -56%

All home deliveries -87% -85% -85% -86%

All pickup points -87% -95% -93% -92%

The main results show that the decisions in urban planning and the choices of the stakeholders We observe that, in terms of traffic, scenario 1, which seems intuitively a bad scenario, allows however a total saving of about 11% with respect to the reference situation.

The main contributor is the IEM family, because delocalising retailing activities in specific points in peri-urban locations has as effect a decrease of the upstream supply-chain costs (because of both the concentration of retailing activities and the fact they are closer to production and distribution activity zones); downstream transport flows have a small decrease, which is explained by the fact that shopping at commercial centres and malls is in general longer in distance but allows a concentration and a decrease of the frequency, which seem to well compensate the distance increase. Scenario 2 has a big impact on both flows, but in an opposing way. Whereas ECM flows decrease highly, IEM ones increase even more.

However, since in the reference scenario the considered IEM are about 10% of ECM flows, the total decrease remains interesting (about 63%).

Scenarios 3 and 4 give over-dominate the other two scenarios, obtaining better results for two reasons. The first is that they concentrate all the destination of goods at retailing level in 15 points of the city's periphery, allowing a good reduction of upstream flows (IEM). Indeed, in both cases, IEM reduction is similar to that of scenario 1. The difference is made in downstream flows (ECM). Scenario 3 allows a reduction of about 85% of road occupancy issues (at both ECM and total levels), whereas Scenario 4 allows a better reduction (95% at ECM level and a global reduction of 93%). Both results are outstanding the other two scenarios and show the potential of e-commerce and proximity deliveries. The main difference is made by the fact that in scenario 3, deliveries are under-optimised with respect to scenario 4 (since home deliveries present still big constraints that do not allow to load the vehicles to the best of their possibilities, which is not the case for reception point deliveries, which the level of goods aggregation is 10 to 20 times higher). In any case, both scenarios (3 and 4) present utopic results that have to be regarded as what they are: the simulation of extreme situations.

In terms of greenhouse gas emissions, we observe slight differences that do not change the essence of the results. The best situation remains scenario 4, and the second best scenario 3, with similar results. Regarding scenarios 1 and 2, we observe that the gains for scenario 2 are about 7% worse than for road occupancy issues, and for scenario 1 about 5% better. This is due to two main facts: the first is that the main contribution to greenhouse gas is made by trucks, which are (for small retailers) old and bad in terms of environmental and greenhouse gas emissions. Moreover, in scenario 2, the main areas of both deliveries and shopping trips are the central parts of the city and the main inhabited parts of the urban area, which have small streets where vehicles circulate a low speeds (and then pollute more than in urban highways). Concerning scenario 1, to reach commercial centres, both trucks and cars prefer using main roads and urban highways, and speeds are higher and more constant, which has a direct impact on reducing CO2 emissions. Although results show that scenario 2 is much better than scenario 1, and both scenarios are extreme, they also show that the bad vision of peripheral retailing areas has to be re-examined to promote a good usage of those structures.

The limits of those analyses are that scenarios are extreme, and non-realistic. They show however the potential of the 4 strategies tested, and show the need of combining them in a way to profit on their synergies to give an equitable offer or retailing in an urban area having a good impact on the environment.

Conclusion and further developments

In this communication we proposed four extreme scenarios to analyse the limits of land-use and distribution policies and their impacts on urban goods transport. Via an integrated framework that takes into account both IEM and ECM flow, we have simulated the four proposed scenarios (household supply respectively in (1) peripheral commercial centres, proximity retailers, e-grocery with home deliveries and (4) e-grocery with deliveries to proximity reception points. This is a « physical » approach; in other words, the economic and social costs have not been directly evaluated, focusing on impacts on road occupancy and greenhouse gas emissions. It is important to note that only the last transport to retailers considered, so it will be needed to extend it to all the urban goods movement field. Results

show the big advantage of e-grocery strategies, which over-dominate the only retailer location scenarios. However, those scenarios are extreme, and in the case of e-grocery, they are based on a total sharing of logistics, dividing the urban area into zones and having a shared B2C distribution system, which is not realistic nowadays. This shows the potential of e-commerce (mainly e-grocery) if two conditions are met: the first is to combine e-grocery with a good location of logistics facilities; the second a total collaboration with stakeholders to share deliveries and vehicles (in the sense of Gonzalez-Feliu and Morana, 2010 and Gonzalez-Feliu, 2011). New simulations, with a more realistic configuration, need then to be made to state on the potential of those approaches and to find a synergic combination of strategies. Last but not least, it is important to obtain good quality data for both shopping trip and proximity distribution characterization.

Future developments of the proposed research are seen in four direction. The firs concerns Modeling issues for ECM, and consists on completing the STG model with a more coherent distribution model and making it independent of the application situation (in other words, finding a model that can be applied to any context with standard data and calibrating it). The second concerns the scenarios, as stated above, to provide more realistic situations and explore the different combination of strategies. The third is that of socio-economic issues, including in the simulation framework outputs as economic and social costs, rto have a sustainable development vision. The fourth concerns proximity deliveries simulation, and aims to provide more realistic simulations at both distribution system organization and consumer's behaviour. A first simulation has been made [START_REF] Durand | La logistique urbaine, facteur clé de développement du BtoC[END_REF] and will be completed and extended.

  Gonzalez-Feliu et al., 2009a,b, 2010a) but using a catchment area model based on the notion of attractiveness (Gonzalez-Feliu, 2010b). The integrated simulation framework works as follows. Consider a city, divided into representative zones. Each zone is defined by two data sets: one defines the economical activities of the zone and the other characterises its population. From the first data set, the FRETURB tool calculates the IEM vehicle flow exchanges between zones for freight distribution and collection, and gives to the STG model the composition of each commercial area. The STG module calculates analogously private cars shopping trips. After that, these flows are integrated in order to calculate the road occupancy issues of running vehicles, for both IEM and ECM flows, in total number of km.PCU for freight-related vehicle trips, to calculate the congestion level. Finally, CO 2 emissions and local pollution rates can be also obtained by considering the characteristics of the different vehicles (professionals and individuals) in the considered city.

Figure 1 .

 1 Figure 1. Chart of the integrated simulation model (adapted from Gonzalez-Feliu et al., 2009a)

Table 1 .

 1 : Main results of simulation

		Km.PCU	Km.PCU	Km.PCU	CO 2 equivalent
		Last transport	ECM	TOTAL
		IEM
	Reference	2,7	26	28,7	6150 t/week
		Mkm/week	Mkm/week	Mkm/week
	All Hypermarkets	-87%	-3%	-11%	-16%


Pierre Bourreau
email: pierre.bourreau@gmail.com

Thierry Poibeau
email: thierry.poibeau@ens.fr

Mapping the Economic Crisis: Some Preliminary Investigations

In this paper we describe our contribution to the PoliInformatics 2014 Challenge on the 2007-2008 financial crisis. We propose a state of the art technique to extract information from texts and provide different representations, giving first a static overview of the domain and then a dynamic representation of its main evolutions. We show that this strategy provides a practical solution to some recent theories in social sciences that are facing a lack of methods and tools to automatically extract information from natural language texts.

Introduction

This paper describes our contribution to the Poli-Informatics 2014 challenge. The organizers of this challenge had made available a series of documents on the 2007-2008 financial crisis. The shared task consisted in developing solutions to address questions such as "Who was the financial crisis?" or "What was the financial crisis?". Of course, these questions are too complex to receive a simple and direct answer. Consequently our strategy has been to provide tools to process and visualize the most relevant data, so that experts can easily navigate this flow of information and make sense of the data. While we believe in semi-automatic corpus exploration, we do not think it is possible or even desirable to provide fully automatic answers to the above questions.

We have mainly used available tools to extract and visualize information. More precisely, we have used the Stanford Named Entity Recognizer [START_REF] Finkel | Incorporating non-local Information into Information Extraction Systems by Gibbs Sampling[END_REF] and the Cortext platform (http://www.cortext.net/) for information extraction. As for data visualization, we have used Gephi [START_REF] Mathieu Bastian | Gephi: an open source software for exploring and manipulating networks[END_REF] to observe semantic and social networks, and the Cortext plat-form to observe the evolution of the domain over time.

The rest of the paper is organized as follows: we first present in section 2 the corpora selected for this study and in section 3 the application of the Stanford Named Entity Recognizer; Section 4 is dedicated to the first graph construction procedure based on Gephi; in Section 5, the construction of the Sankey diagrams is explained, before concluding. Note that all the maps provided are also available at http://www.lattice. cnrs.fr/PoliInformatics2014. Some of them integrate interactive facilities (dynamic display of the complete list of terms related to a given topic, etc.) when online.

Corpora Selected for the Analysis

Different corpora were made available for the unshared task. From those, we chose to focus on the reports, and excluded bills and auditions as the former seemed to be informationally richer and easier to process. Therefore, we worked on three different files: the Congressional Reports "Wall Street and the Financial Crisis: Anatomy of a Financial Collapse" (referred to as AoC in the rest of the document), "The Stock Market Plunge: What Happened and What is Next?" (referred to as SMP), and the "Financial Crisis Inquiry Report" (referred to as FCIC). Each of these files was accessible as a PDF, or alternatively as a list of HTML pages, each page corresponding to a page of the PDF file.

The first task we performed was to transform the HTML files into a single text document (thanks to a Python script). In the case of AoC, an option was added to remove page numbers, which were present in the content part of the HTML file. Moreover, we normalized the files so that every space break (line breaks, multiple space breaks or tabular breaks) was changed into a single space break. After this procedure, we obtained three text files: AoC.txt, SMP.txt and FCIC.txt.

Named Entity Recognition and Normalization

The next step was to extract named entities from the different corpora. In order to do so, we used the Stanford NER, based on Conditional Random Fields, with MUC tags (Time, Location, Organization, Person, Money, Percent, Date) [START_REF] Finkel | Incorporating non-local Information into Information Extraction Systems by Gibbs Sampling[END_REF]. We were indeed interested in extracting organizations and persons so as to get information about who are the actors of the financial crisis, but dates were also necessary to be able to represent the temporal evolution of the financial crisis.

Because the SMP corpus is too small, we used it for tests but results are not commented in the present article.

Certain entities appear under different forms. For instance, "Standard and Poor" might occur as "Standard & Poor", "S&P" or "Standard & Poor's executive board" (this last sequence in fact refers to a slightly different named entity); in a similar fashion, a person as "Mary Schapiro" may appear as "Schapiro", or "Miss Schapiro" or "Chairman Schapiro". A normalization process is therefore needed.

A large number of references on the subject exist: see, among many others, [START_REF] Zhang | Entity linking with effective acronym expansion instance selection and topic modeling[END_REF][START_REF] Han | A generative entitymention model for linking entities with knowledge base[END_REF][START_REF] Gottipati | Linking entities to a knowledge base with query expansion[END_REF][START_REF] Rao | Entity linking: Finding extracted entities in a knowledge base[END_REF]. We chose a rather simple approach that performed well on our corpus based on the following rules • r Org : if two organizations ORG1 and ORG2 are made of more than one word, and share the same initials, they are considered equal; similarly, if the sequence ORG1 is in ORG2 or ORG2 in ORG1, they are considered to refer to the same entity.

• r Pers : two persons PERS1 and PERS2 are supposed to refer to the same person if the sequence PERS1 is in PERS2 (or PERS2 in PERS1); the same hypothesis stands if the last string in PERS1 (resp. PERS2) is in PERS2 (resp. PERS1).

We did not notice a significant improvement when using more sophisticated methods (cf. above) so we keep these simple and traceable set of rules.

We then had to generalize the approach since the previous strategy is not enough to cluster together all the relevant linguistic sequences corresponding to a same entity. Based on the rules r Org and r Pers , we tested two clustering approaches:

• P Max : consider the most frequent entities E1 in the set of words S1 and E2 in S2. If they are identical according to r ORG , S1 and S2 are merged into a single cluster.

• P Av : given AV the average number of occurrences of a person or oganization in the corpus, consider the sets A1 ⊆ S1 and A2 ⊆ S2 made of all entities that occur more than AV times in the corpus. If all items E1 ∈ A1 and all E2 ∈ A2 are identical according to r ORG , then S1 and S2 are merged.

The normalization subprocess P Max (resp. P Av ) is iterated until a fixpoint is reached in the set of sets of entities. After evaluation the normalization strategy based on P Av turned to be the most efficient one. Even if basic, this normalization strategy proved helpful for further analysis.

Vizualizing entities

We used the Gephi software [START_REF] Mathieu Bastian | Gephi: an open source software for exploring and manipulating networks[END_REF]) so as to create graphs for each corpus, such that:

• a node corresponds to a cluster of persons or organizations in the corresponding corpus (each node is labeled with the most frequent entity in the corresponding cluster);

• an edge between two nodes corresponds to the number of co-occurrences of the two nodes within the same sentence in the corpus.

We chose to consider persons and organizations together since they can play a similar role in the event, and metonymy is often used, so that a person can refer to a company (and vice versa).

We then used the Force Atlas algorithm so that only pairs of linked nodes attract each other. We assign a measure of betweennes centrality (BC) to each node, which makes nodes with highest degrees (i.e. nodes with the highest number of links) be bigger; finally, we used a clustering algorithm: the Louvain Method [START_REF] Vincent | Fast unfolding of communities in large networks[END_REF], to detect communities in the graph, and we colored the nodes of each community with a distinct color; intuitively, we want the number of intracommunities edges to be high, while the number of inter-communities edges is low.

This process leads to the visualization of two properties: i) the size of a node gives a measure of the dependance of the corresponding set of entities to other sets of entities. With this measure, we expect to highlight the role of key organizations and persons during the financial crisis who have influenced other organizations/persons, etc.; ii) the same process is then used to highlight strong links between persons and organizations.

The results can be seen on figure 1 and figure 21 . Of course some links are not really informative (for instance the link between an organization and its CEO); other links express information that may be registered in different knowledge bases (see for ex. the link between Scott Polakoff and OTS, or between Fabrice Tourre and Goldman Sachs). However, we expect to extract less predictable links that could be of interest for scholars and experts in the field. As an example (and even if this is still not really surprising), we can observe (figure 2) the links between the Fed Consumer Advisory Council and the Board of Governors (for ex. Bernanke, Mark Olson, and Kevin Warsh) since the first group of people (the council) warns the Board of Governors of the crisis that is just beginning.

These visualizations should be explored and tested by specialists who could evaluate their real benefits. A historic view on the data would also be useful to analyse the dynamics and the evolution of the crisis, through for example the evolution of terms associated with named entities over different periods of time.

Visualizing temporal evolution

We tried to explore and visualize the temporal evolution of the financial crisis, more specifically the evolution of the perceived role of organizations over time. To do so, we produced Sankey diagrams of the correlation of organizations and domain related terms in the corpus. With this strategy, Sankey diagrams take into account the temporal evolutions of entities and actions along the crisis.

To this aim, we re-used the results of the named entity recognizer (see section 3). All the data is extracted from the text itself, including dates. A dates is currently associated only with the sentence it appears in. In other words, the scope of dates (how many events / sentences depend from a given date) is currently not taken into account but this should be addressed in the near future.

Organization names as well as dates are normalized, so that only years are kept in the end (note however, that a more fine-grained representation, at the month level for example, would be desirable for further investigation). Lastly, we only selected occurrences of years in the range , since documents may refer to past and future legislation (but the analysis here is of course not trying to make any prediction for the future). Few but some references are made to the 1929 crisis for instance: those were not relevant for our analysis and were then removed.

We then run the Lexical Extraction module of the Cortext platform (for technical details see http://docs.cortext.net/ lexical-extraction/) in order to extract the N most relevant terms in AoC and FCIC. We were thus able to extract the most representative cooccurrences of named entities along with domain specific terms over time.

An overview of the diagram built on FCIC is given on Figure 3 for information. These representations are in fact interactive: by clicking on the different objects (the colored sticks, the grey tubes) it is possible to get the list of terms that are common (or different) between two different periods of time. Associations evolve, hence the tubes can split or merge, depending on a change in the context, i.e. in the role of an entity or in the way it is perceived by other actors.

Figure 3 reveals a modification in the data between 2006 and 2008, a period which approximates the start of the financial crisis. For instance, the stream in purple in this graph reveals many cooccurrences of Fannie Mae and subprime loans for the period 1990-2007 while for the period 2008-2010, Fannie Mae is more closely associated with 'bank regulators', or 'Federal Financial Services Supervisory Authority'. In a more general way, all the streams of data represented in the diagram are dramatically modified after 2007.

The AoC diagram (Figure 4) shows the very same modification of data streams, which suffer from a change after the 2007 time period. This representation gives immediate access to key facts. For example, the payment default of the Washington Mutual Bank (WaMu) appears clearly. Other examples gives an immediate and meaningful view of the general situation over time but a more fine grained analysis would be both possible and desirable.

Discussion

In this paper, we have explored the use of natural language processing tools to extract and visualize information on the 2007-2008 financial crisis. We first presented a static view of the domain based on cooccurrences of named entities (mainly persons and organizations) within the corpus. We then showed how the evolution of the domain can be represented taking time into account. In this second experiment we focused on co-occurrences of organizations and domain specific terms and showed that the terms evolve over time as well as their association with company names, making it possible to get a picture of the domain without having to read first the whole documentation.

These representations are inspired by recent theories in social sciences that propose not to define a priori groups of interest but to directly take into account actors and observe regular patterns or regular behaviors (Law and Hassard, 1999;[START_REF] Latour | Reassembling the Social: An Introduction to Actor-Network-Theory[END_REF]. Existing natural language processing tools now make it possible to generate such representation directly from texts, which was not possible until recently [START_REF] Venturini | Once upon a text : an ant tale in text analysis[END_REF]. Traditional representations based on coword analysis are not enough any more and recent advances in named entity recognition, relation and event extraction mean that the richness of texts can be better exploited.

Future Work

Perspectives are twofold: on the one hand enhance data analysis so as to provide more relevant maps and representations, and on the second hand work closely with domain experts and provide interactive ways of navigating the data.

On the technical side, several improvements could be done. For instance, it would be interesting to complete the extraction of technical terms with relevant verbs so as to obtain more relevant connections between entities. The goal would be to better characterize the role played by the different entities. Also, dates considered in the temporal analysis could be scaled in months or days. In the same direction, it could be interesting to test different named entities normalization strategies, and to test our methods on more texts from different sources.

Concerning interactions with experts, it is clear that end users could provide a very valuable contribution in the selection of relevant data as well as in the way they are linked and mapped. Some experiments are currently being done with a focus group gathering social science as well as information science experts. They will assess that the solution is useful and workable and more importantly, will give feedback so as to provide better solutions.

Figure 1 :

 1 Figure 1: Visualization of links between entities with Gephi (AoC corpus). The original map is dynamic and allow end users to navigate the data.

Figure 2 :

 2 Figure 2: Visualization of links between entities with Gephi (FCIC corpus)

Due to their large size and complexity, figures presented in the end of this paper are small and not fully readable; however, we hope they give the reader a flavor of the kind of representation possible. See http://www. lattice.cnrs.fr/PoliInformatics2014 to visualize the original maps.

Acknowledgments

The authors are thankful to Elisa Omodei for her help in using the Cortext platform. We would also like to thank the two reviewers from the PoliInformatics challenge for their useful feedback and suggestions on the work done. We are also grateful to the experts involved in our focus group.

This research was partially funded by the CNRS Mastodons Aresos project.


Thierry Poibeau
email: thierry.poibeau@ens.fr

Processing Mutations in Breton with Finite-State Transducers

One characteristic feature of Celtic languages is mutation, i.e. the fact that the initial consonant of words may change according to the context. We provide a quick description of this linguistic phenomenon for Breton along with a formalization using finite state transducers. This approach allows an exact and compact description of mutations. The result can be used in various contexts, especially for spell checking and language teaching.

Introduction

Celtic languages (Welsh, Cornish, Irish, Scottish-Gaelic, Manx, etc.) are known to support a common feature: the initial consonant of different types of words (esp. nouns, adjectives and verbs) is modified in certain contexts and after certain function words (e.g. prepositions and determiners for nouns and adjectives; auxiliaries for verbs). This phenomenon known as "mutation" has been largely studied and described from a linguistic point of view. Formal descriptions have even been proposed, especially [START_REF] Mittendorf | A treatment of welsh initial mutations[END_REF] for Welsh.

In this paper, we investigate mutations in Breton. 1 Our study is largely inspired by the previous study by Mittendorf and Sadler for Welsh: We share with these authors the idea that "initial mutation is close to inflection in nature and is essentially a morphosyntactic phenomenon". We propose to process this phenomenon with finite state transducers. In fact, we propose two formalizations: in the first one, mutations are processed by directly storing the lexical forms with mutations in a dictionary of inflected forms; in the second one, local rules encoded using finite state transducers are applied dynamically, depending on the context. We show that this strategy allows for an exact and compact description of the phenomenon, since transducers directly encode grammar rules.

The paper is organized as follows: we first propose a linguistic description of this phenomenon. We then explore the two strategies exposed in the previous paragraph: a dictionary of inflected form vs local grammars encoded using finite state machines. We conclude with a discussion and an overview of the practical use of this implementation.

A Quick Description of Mutations in Breton

As said in Wikipedia (http://en.wikipedia.org/wiki/Breton mutations), "Breton is characterized by initial consonant mutations, which are changes to the initial sound of a word caused by certain syntactic or morphological environments. In addition Breton, like French, has a number of purely phonological sandhi features caused when certain sounds come into contact with others." The following details are then added: "the mutations are divided into four main groups, according to the changes they cause: soft mutation (in Breton: kemmadurioù dre vlotaat), hard mutation (kemmadurioù dre galetaat), spirant mutation (kemmadurioù c'hwezhadenniñ) and mixed mutation (kemmadurioù mesket). There are also a number of defective (or incomplete) mutations which affect only certain words or certain letters." A same word can thus appear differently depending on these classes of changes (for example the noun tad father -becomes da dad -your father; he zad -her father; etc. because of the possessive pronouns da and he that entail different kinds of mutation).

The best approach to give an idea of mutations is to consider some examples. "Soft mutations" refer to the fact that after the definite article ar (and its variant an) or the indefinite article ur (or un) the initial consonant of singular feminine nouns is subject to the following changes:

• K → G, ex. Kador (chair) → Ur gador • T → D, ex. Taol (table) → Un daol • P → B, ex. Paner (basket) → Ur baner • G → C'H, ex. Gavr (goat) → Ur c'havr • GW → W, ex. Gwern (mast) → Ur wern
Note that in nouns referring to objects and abstract notions can be either masculine or feminine (there is no neuter case).

Although the phenomenon is well known, its description is not straightforward since it involves a large number of parameters and different types of information (lexical, morphological, semantic). For example, plural masculine nouns referring to male persons have the same behavior as singular feminine nouns (but this is only true for plural masculine nouns referring to people, not for all plural nouns). It is therefore necessary to distinguish different categories of nouns.

• K → G, ex. Kigerien (butchers) → Ar gigerien • T → D, ex. Tud (people) → An dud • P → B, ex. Pesketaerien (fishermen) → Ar besketaerien • G → C'H, ex. Gellaoued (French) → Ar C'hallaoued • GW → W, ex. Gwerzherien (sellers) → Ar werzherien
These mutations also affect adjectives, provided that the noun preceding the adjective ends with a vowel or with the consonant l, m, n, or r.

• K → G, ex. Kaer (nice) → Ur gador gaer (a nice chair)

• T → D, ex. Tev (thick) → Ur wern dev (a thick mast)

• P → B, ex. Paour (poor) → Ur vamm baour (a poor mother) There are different series of mutations depending on the functional word preceding the noun (and the adjectives if any). It is one of the main difficulties of the language since this phenomenon changes the initial of the words: after mutation, words cannot be found anymore directly in the dictionary.

A comprehensive description of this phenomenon can be found in traditional grammars of the language: see especially [START_REF] Kervella | Yezhadur bras ar brezhoneg[END_REF]), Hemon (1984) and [START_REF] Stump | Agreement vs. incorporation in breton[END_REF] for a formal description of agreement in Breton.

Automatic Processing of Mutations in Breton

Two approaches are possible:

• store all the inflected lexical forms and their mutations in a dictionary. Mutation is then considered as a case of word variation (like the alternation singular/plural);

• compute on the fly the lexical form in context, which is an interesting strategy for text generation or, more directly, in the context of text authoring (for example to assist students producing texts in Breton).

In this paper, we consider both approaches since they are both relevant depending on the context.

The following section describes two ways of processing mutations in Breton. We discuss their interest and their applicability to the problem.

A Comprehensive Dictionary of Inflected Forms

This solution is the simplest one: all inflected forms including those with modified initial letters are included in the dictionary. The dictionary remains manageable and ambiguity by the new lexical forms is limited. Below is a short extract of a dictionary of inflected forms including lexical forms after mutation:

kador,kador.N:fs taol,taol.N:fs gador,kador.N:fs daol,taol.N:fs c'hador,kador.N:fs zaol,taol.N:fs

The format of the dictionary is the one defined by LADL (Courtois and Silberztein, 1990): inflected forms are followed by a lemma (separated by a comma). The category of the word can then be found (N for noun) as well as morphosyntactic features (fs: feminine singular). However, this solution is not fully satisfactory since it does not explain why a given form is used in a given context. It would be relevant to provide a more dynamic description of the process taking into account the different constraints we have seen in the previous section.

A Finite State Approach

We have seen in the introduction that mutations refer to a simple change in the first letter of certain words in certain contexts. This phenomenon is essentially local (it does not require to take into account a large context) so finite state transducers seem to be a relevant choice. These transducers will directly encode the rules described in the grammar of Breton that just need to be made more formal.

Below (Figure 1) is an example of such a finite state transducer. This graph directly encodes all the constraints involved in the process. Elements that appear in boxes describe a linguistic sequence while elements appearing under the boxes correspond to the rewriting part of the transducer (i.e. the transduction). Here is a description of the different elements that can be used for the linguistic description:

• Tags between < and > refer to morphosyntactic categories (DET for determiner, N for noun, A for adjective, etc.);

• The elements after the colon are morphological features (f: feminine , s: singular...);

• The # sign indicates a separator between words (e.g. blank spaces between words);

• A gray box refers to a subgraph (here LettreMin refers to all lowercase letters; please note that the sequence described here corresponds to any sequence of letters between separators, i.e. tokens, because of the recursion on the state itself);

• Other items appearing in a box correspond to characters (or lexical forms);

Here, we see clearly that K becomes G if the sequence is a fem. sing. noun appearing immediately after a determiner. Notations correspond to the ones defined by the LADL team, see Silberztein (1993) and [START_REF] Paumier | Unitex 3.0 User Manual[END_REF] -other frameworks could of course be used like the Xerox FST toolbox [START_REF] Beesley | Finite State Morphology[END_REF].

Transducers provide a unified view of the different contraints along with a rewriting process. Recursive transducers (RTN) make it possible to obtain a concise and effective formalization. Different linguistic phenomena can be processed using a cascade of automata applied one after the other. For example, it seems relevant to re-use the graph encoding noun mutations to process adjectives. If all the mutations for nouns have been encoded and compiled in a single graph called MUT, it is then possible to write the fllowing transducer (figure 2) for adjectives. MUT also encodes the constraints on the last vowel of the previous word (only adjectives following a noun ending with a vowel or with l, m, n or r are subject to this mutation).

Implementation and evaluation

Local contextual grammars can be encoded using various techniques but finite state transducers seem to be the most effective and readable way to encode these rules. This is in line with previous work: for example [START_REF] Mittendorf | A treatment of welsh initial mutations[END_REF] use the Xerox finite state transducer toolbox to implement mutations in Welsh. Our proposal is very close to theirs.

Various other platforms allow the manipulation of finite state transducers for local grammars. Scripting languages (like perl or python) also offer a good solution but these languages are made to manipulate strings. However for mutations we need to have different information on the words themselves, hence using a linguistic toolbox seems more appropriate.

The implementation of this linguistic phenomenon using finite state transducers produce a compact and accurate description. Grammars are easy to modify and maintain. Additionally different grammars could be developed to take into account local variations and dialects.

Discussion

We have presented a practical approach to process mutations in breton. The approach is based on well known techniques (finite state transducers) that provide an accurate and efficient description of the phenomenon. The technique used reveal the fact that mutation is essentially a morphosyntactic phenomenon, as said in the introduction.

However, the main challenge does not lie in the proposed formalization. Endangered languages are generally not well supported (lack of resources and automatic tools) and we think this kind of contribution could have a positive impact on the evolution of the language. If relevant tools exist, it could be a way to attract new attention and help language students acquire a good command of the language. Since a large part of language learners study at home, having dynamic tools assisting text production would be a real plus.

Adding explanation to the above rules would make it possible to generate suggestions during text production or text revision. From this perspective, the description we provide could serve as a basis for a spell checker of the language.2 Detailed explanations would make the whole system usable for assisting people during language learning (e.g. to explain why a given sequence in not fully correct in case a word should appear with a mutation, etc.). This strategy could easily be re-used for other languages and other linguistic phenomena.

Figure 1 :

 1 Figure 1: Graph MUT-Detfs-K-G

Figure 2 :

 2 Figure 2: Graph MUT-Adj-K-G

Breton is a Celtic language spoken in Brittany (Western France) According to recent studies,

200,000 persons understand the language but only 35,000 practice it on a daily basis.

Note that different initiatives exist to develop natural language tools for processing Breton. We should cite more specifically the association Drouizig http://www.drouizig.org/ that has developed a spell checker independently of this study.


Sustainable urban logistics: Concepts, methods and information systems Preface

Jesus Gonzalez-Feliu, Jean-Louis Routhier and Frédéric Semet Urban logistics is a wide studied subject. Indeed, since more than twenty years, several researchers and practitioners deal daily with different issues concerning planning and management of urban freight transport systems. Nowadays, two definitions of city/urban logistics are retained. The first is that of Taniguchi et al. [START_REF] Taniguchi | City Logistics-Network modelling and Intellegent Transport Systems[END_REF] who define city logistics as « the process for totally optimizing the logistics and transport activities by private companies in urban areas while considering the traffic environment, the traffic congestion and energy consumption within the framework of a market economy ». The second, more related to the vision of Ambrosini and Routhier [START_REF] Ambrosini | Objectives, methods and results of surveys carried out in the field of urban freight transport: an international comparison[END_REF] and Anderson et al. [START_REF] Anderson | Urban logistics--how can it meet policy makers' sustainability objectives[END_REF], is not related to the notion of optimization but to organization. In this sense, we can define urban logistics as the pluridisciplinary field that aims to understand, study and analyze the different organizations, logistics schemes, stakeholders and planning actions related to the improvement of the different goods transport systems in an urban zone and link them in a synergic way to decrease the main nuisances related to it. Although the field has been studied for almost 40 years, it is only at the end of the XX th century that we observe the main coordinated actions of research having a direct impact into practice.

Nowadays, we can observe thousands of specific actions in urban logistics, many directly issued from research programs, but not all of them are still operational. This is mainly due to the different stakeholders that are seen in urban logistics, as well as the wide variety of aims and stakes and to the consequent difficulties to pursuit collaborative actions. Public stakeholders (politicians, city planners, public transport managers, regional or national technical services) are on a collective welfare vision and aim to reduce the main nuisance attributed to freight transport, i.e. congestion, pollution, global warming and noise without penalizing urban areas and also while creating employment when possible. Private stakeholders (shippers, transport and logistics operators, retailers, wholesalers, craftsmen, real state stakeholders, tertiary activities, etc.) are on an economic efficiency vision and aim to reduce costs and/or increase service quality, of course with an eye on the environment but not as a primordial criterion. It is clear that for each stakeholder the notion of sustainability is not the same. Although all of them refer to the Kyoto protocol, the importance that they give to each of its components (economic, environmental and social) is not the same, and it is often difficult to provide a unified vision to compare proposals and solutions. Furthermore, those issues are amplified due to the high constrained environment of urban goods transport and the interaction that it makes with personal transport (although goods transport is often indicated as source of nuisance, it is proven that its inefficiency is a consequence of the nuisances personal transport have on goods transport).

In this context we think important to make the links between research and practice, and provide a general framework to help both public and private stakeholders in managing and planning urban logistics systems. This book aims to provide both a conceptual framework for urban logistics planning and management and to create a basis for deploying solutions that aim to reduce the main nuisances related to urban goods. In addition to public authorities' aims and goals, the book highlights the importance of private actors, and shows how supply chain management can deal with the problems of the last urban mile and its integration in global logistics chains.

The book is divided in four parts. The first aims to describe and set the current situation, not only on the (historical) viewpoint of city planners but also on that of sustainable managers. The second part proposes a set of methodological chapters, written by key authors, which aim to support decision makers in terms of understanding and simulating the current situation in terms of urban goods flows. The third part is more related to tactical planning actions, including both public and private viewpoints. The fourth part is focused on strategic planning issues, also on both viewpoints.

The first part is composed on four chapters, two related to the links of urban logistics with supply chain management, and two focused on the relations between local governance and logistics development.

In the first chapter [START_REF] Boudouin | Supply chains and urban logistics platforms[END_REF], Daniel Boudouin, Christian Morel and Mathieu Gardrat present the main links between supply chain management and urban logistics, focusing on the natural interfaces between both of them: urban logistics platforms. Those links are presented from public and private sector viewpoints. A typology of urban logistics platforms is proposed, based on the structure of present and hypothetical future demand in terms of urban goods movements. Finally, the authors formulate several recommendations on new forms of organizations, technologies and governance.

If the first chapter focuses on urban logistics to see the links to global supply chain management (bottom-up), the second one has a top-down approach [START_REF] Morana | Sustainable Supply Chain Management in Urban Logistics[END_REF]. Joëlle Morana presents the main concepts of sustainable supply chain management and applies them to urban logistics. In this chapter, the links are not physical but organizational, and are more related to private stakeholders. The place of urban goods transport in a sustainable supply chain management process is shown, and illustrated via the example of the urban consolidation center of Padova (Italy). This example illustrates the need of collaboration among both private and public stakeholders and the importance of a sustainable thinking which do not focuses only on environmental hopes but also on economic and social facts.

The third chapter adopts clearly a public planner's perspective [START_REF] Ballantyne | Identifying the need for freight to be included in local authority transport planning[END_REF]. Erica Ballantyne and Maria Lindholm show, via an interview-based study, the issues related to including the identification of goods transport demand needs into urban plans. The authors present the similarities in the way that local authorities from Sweden, the UK, and Baltic Sea Region countries perceive urban freight problems, and discuss the relationships between local authorities and freight stakeholders. The main findings show that local authorities have begun to acknowledge freight transport more often but the issues faced by the freight industry are still not fully understood. Finally, they highlight the potential benefits of including freight stakeholders in the transport planning process, encouraging more meaningful discussions with key freight stakeholders at an early stage in the transport planning process.

Laetitia Dablanc shows in chapter 4, via a case study on the Los Angeles mega-region, the main stakes and issues of North American authorities in terms of logistics needs and platform location and development [START_REF] Dablanc | Logistics Sprawl and Urban Freight Planning Issues in a Major Gateway City[END_REF]. Moreover, an in-depth analysis of the logistics sprawl phenomena in Los Angeles allows the author to focus on the links between local governance and logistics activities deployment, especially for the jobs and tax revenues they can generate in a time of economic difficulties. She examines two cases in Los Angeles: the first is a traditionally industrial city close to downtown; the second is the sprawling community of the "Inland Empire," east of the L.A. metropolitan area. In both cases, the author observes the influence that the warehousing/logistics industry has on the economic life of working class areas, raising questions about the pros and cons of logistics activities for local communities.

The second part is centered on data production, more precisely on the methods that allow surveying, collecting, processing and/or reconstructing the information which can be needed to define and understand the current situation in terms of urban goods flows. It contains three chapters. Chapters 5 and 6 are related on survey and data collection methods, and chapter 7 on statistical methods for estimating data from current databases. Julian Allen, Christian Ambrosini, Michale Browne, Daniele Patier, Jean-Louis Routhier and Alan Woodburn propose a wide review of survey methods that have been carried in Europe, based on the conclusions of the BESTUFS II project [START_REF] Allen | Data Collection for Understanding Urban Goods Movement[END_REF]. From survey work carried out with experts in eleven European countries, a comparison of urban freight transport data collection efforts is made to better understand what currently takes place and to identify examples of good practice. Authors observe that the extent of urban freight data collection varies significantly between the European countries, as existing urban freight data comes mainly from the disaggregation of national survey results. Finally, authors identify a set of gaps in data collection, as well as the need for greater standardization in data collection methods and in analysis and reporting of this data.

The same subject is studied by José Holguin-Veras and Miguel Jaller, who analyse characteristics and unique features of the freight system, focusing on data requirements of different modeling techniques [START_REF] Holguín-Veras | Comprehensive freight demand data collection framework for large urban areas[END_REF]. Although both chapters refer to data collection, authors here focus on modeling and estimation, and study the roles of various data collection procedures. The analyses produce a set of findings of relevance to the design of comprehensive freight data collection frameworks for mid-size and large urban areas like those that can be seen in North America. From those findings, authors propose a modular data collection framework to support urban stakeholders' decisions concerning data collection methods depending on their needs and constraints.

Jesus Gonzalez-Feliu, Christian Ambrosini, Florence Toilier and Jean-Louis Routhier propose in chapter 7 a statistical-based modeling approach to propose a data estimation tool that can be transposed to different cities, avoiding the needs of making very costly surveys . The proposed framework needs standard inputs able to be obtained by public authorities and/or private stakeholders to make a diagnosis of urban logistics in current situations. The joint process of collecting data and modeling is described, and the different modules of the framework are presented. The authors conclude by presenting the main applications and further developments.

The third part deals with tactical planning. In other words, chapters of this part propose different methods to support stakeholders in middle-term decisions (Crainic and Laporte, 1997), i.e., at a monthly-weekly horizon. Two main subjects are studied: consolidation and time constraints.

In chapter 8, Simona Mancini, Jesus Gonzalez-Feliu and Teodor Gabriel Crainic focus on combinatorial optimization, more precisely on vehicle routing problems [START_REF] Mancini | Planning and Optimization Methods for Advanced Urban Logistics Systems at Tactical Level[END_REF]. The authors focus on methods related to advanced consolidation systems. The authors present the main categories of systems related to consolidation, and relate to each category a group of problems. Then they focus on optimization methods, presenting the main variants and making a critical discussion of its suitability. Finally, the authors propose a socio-economic analysis to study the leverages and limits of urban consolidation systems, based on a set of interviews.

Jesus Munuzuri and Ron Van Duin deal with the issue of access time windows [START_REF] Muñuzuri | Time constraints: the cost of sustainability[END_REF]. First, the authors motivate the importance of access times policies, and present a panorama of Dutch cities. After that, the authors present and apply a VRP-based methodology to estimate these costs, which should be brought into the overall cost-benefit analysis of urban time constraint policies. The main notions of vehicle routing optimization with access time windows are presented, and a genetic algorithm is presented. Finally, an example of application is shown as illustration.

Finally, the last part of the book focuses on strategic planning and assessment. Chapter 10 is related to the notion of logistics pooling, which can be seen as an alternative to classical urban consolidation tactics [START_REF] Morana | Urban Consolidation and Logistics Pooling[END_REF]. Authors propose a framework for strategic planning and ex-ante evaluation of logistics pooling systems. First, the authors present the main concepts of logistics pooling and their applications to urban delivery services. Then, an information systems-based framework for planning and evaluation is described, from which a set of indicators are identified. To illustrate this framework, the authors present a case study from a French urban logistics pooling system. Agostino Nuzzolo and Antonio Comi propose in chapter 11 a framework to forecast the direct effects of urban logistics measures [START_REF] Nuzzolo | Direct Effects of City Logistics Measures and Urban Freight Demand Models[END_REF]. Such effects can be internal (transportation cost variations) or external (variations of pollution, noise and road accidents). First the authors consider the shopping and restocking components of urban freight mobility and the relative actor's choices that can be influenced by city logistics measures. After that they consider the road system with its various components, and the demand models are analyzed with particular attention to shopping demand models. The model is calibrated and the possible applications are enounced. Edoardo Marcucci and Valerio Gatta lead with the heterogeneity in retailers' choices concerning the acceptability of urban logistics measures. The authors report the result of a stated ranking exercise conducted in the Limited Traffic Zone of Rome (Italy) in 2009 focusing on retailers and their acceptability to pay for different measures concerning urban deliveries [START_REF] Marcucci | Behavioral Modeling of Urban Freight Transport[END_REF]. The authors make a comparison between two model specifications and study the non-linear effects for the variations of the levels of the attributes considered. The results obtained are very interesting and meaningful from a policy perspective since they show potentially differentiated effects of the policy implemented in deep contrast with the, often assumed, homogenous effect hypothesis.

Finally, Jesus Gonzalez-Feliu, Eiichi Taniguchi and Bruno Faivre-d'Arcier propose an overview on one important but little studied issue in urban logistics: that of financing and/or refunding urban logistics solutions [START_REF] Gonzalez-Feliu | Financing Urban Logistics Projects[END_REF]. After presenting the main refunding strategies in urban economics and relating them to urban logistics, the authors propose to analyze the potential of cost benefit analysis in urban logistics. The general method and an application to the deployment of delivery space booking systems are proposed, and results discussed.

Finally, authors list the main fields where public-private partnerships can be applied and identify the main refunding issues related to them.

With that plethora of approaches, proposed by key authors, this book aims to give readers a basis for understanding, planning and managing urban logistics systems with the respect of the sustainability development conditions, allowing a wide variety of stakeholders a unified and pluridisciplinary overview of the main subjects concerning sustainable urban logistics.


Arnaud Blouin
email: arnaud.blouin@irisa.fr

Naouel Moha
email: moha.naouel@uqam.ca

Benoit Baudry
email: benoit.baudry@inria.fr

Houari Sahraoui
email: sahraoui@iro.umontreal.ca

Slicing-based Techniques for Visualizing Large Metamodels

In model-driven engineering, a model describes an aspect of a system. A model conforms to a metamodel that defines the concepts and relationships of a given domain. Metamodels are thus corner-stones of various meta-modeling activities that require a good understanding of the metamodels or parts of them. Current metamodel editing tools are based on standard visualization and navigation features, such as physical zooms. However, as soon as metamodels become larger, navigating through large metamodels becomes a tedious task that hinders their understanding. In this work, we promote the use of model slicing techniques to build visualization techniques dedicated to metamodels.

We propose an approach based on model slicing, inspired from program slicing, to build interactive visualization techniques dedicated to metamodels. These techniques permit users to focus on metamodel elements of interest, which aims at improving the understandability. This approach is implemented in a metamodel visualizer, called Explen.

I. INTRODUCTION

The fundamental idea of Model-Driven Engineering (MDE) is to consider models as first-class entities. A model conforms to a metamodel that describes the concepts of a given domain. Metamodels, represented graphically as class diagrams, are thus corner-stones of various meta-modeling activities that require a good understanding of the metamodels or parts of them. Such activities consist of, for instance, transforming models into code, creating editing tools for a metamodel, or comparing metamodels. The current mainstream metamodel editors, such as EcoreTools provided by the Eclipse Modeling Framework (EMF) 1 , however, offer basic interactive features to navigate through metamodels (physical zoom, scroll bars, etc.). As soon as metamodels become larger, understanding and manipulating metamodels becomes a tedious task using these basic interactive features. For instance, Figure 1 is an overview of the metamodel UML [START_REF] Omg | UML 2.1.1 Specification[END_REF] obtained using the physical zoom of EcoreTools. Many classes are gathered and reduced so that identifying one class or its relations with other ones becomes awkward.

When modelers are interested only in a specific part of a metamodel, they may want to focus on such a specific part by, for instance, hiding the rest of the metamodel. For instance, for the visualization of a metamodel, a modeler may be interested in semantic relationships between classes such 1 http://www.eclipse.org/modeling/emf/ as the inheritance tree of a given class or the classes linked by a composition reference to a given class. With the current editors, modelers are forced to manually and astutely combine sequences of filtering and navigation primitive operations to rebuild these parts of interest. This manual exploration task may be time-consuming and error-prone.

Visualization techniques are broadly used in software engineering and have proven their usefulness for software comprehension and in particular, interactive visualization that provides meaningful navigation capabilities [START_REF] Storey | Cognitive design elements to support the construction of a mental model during software exploration[END_REF]. Gračanin et al. summarized the benefits in terms of comprehension brought by software visualization to different domains [START_REF] Gračanin | Software visualization[END_REF]. Closely, previous work on UML class diagrams highlights the research interest on improving the understanding of class diagrams [START_REF] Guéhéneuc | TAUPE: towards understanding program comprehension[END_REF], [START_REF] Yusuf | Assessing the comprehension of UML class diagrams via eye tracking[END_REF], [START_REF] Porras | An empirical study on the efficiency of different design pattern representations in UML class diagrams[END_REF]. Our contribution is twofold: we show that model slicing can be used to build interactive visualization techniques dedicated to metamodels; we propose a software engineering approach to ease the development of model slicers to be used within metamodel visualizers as a visualization engine. Model slicing permits users to focus on metamodel elements of interest, which aims at improving the understandability. We developed a metamodel visualizer, namely Explen, embedding slicing-based interactive visualization techniques.

The paper is organized as follows. Section II introduces model-driven engineering. Section III depicts a motivating scenario. Section V describes how model slicing can be used to develop interactive visualization techniques for improving the understandability of large metamodels. The paper ends with the related work (Section IV) and the future work (Section VI).

II. MODEL-DRIVEN ENGINEERING

The traditional way scientists use to master complexity is to resort to modeling. According to Jeff Rothenberg, "Modeling, in the broadest sense, is the cost-effective use of something in place of something else for some cognitive purpose. It allows us to use something that is simpler, safer or cheaper than reality instead of reality for some purpose. A model represents reality for the given purpose; the model is an abstraction of reality in the sense that it cannot represent all aspects of reality. This allows us to deal with the world in a simplified manner, avoiding the complexity, danger and irreversibility of reality" [START_REF] Rothenberg | The Nature of Modeling[END_REF]. In engineering, one wants to 1 break down a complex system into as many models as needed to address all the relevant concerns in such a way that they become understandable enough. The fundamental idea of MDE [START_REF] Schmidt | Model-driven engineering[END_REF] is to consider models as first-class entities in software-development processes. MDE aims at reducing the complexity associated with developing complex software systems. In MDE, a model describes an aspect of a system and is typically created or derived for specific development purposes. Each model conforms to a well-defined metamodel that describes the concepts and relationships of a given domain. For instance, Figure 2 depicts an excerpt of the Ecore metamodel 1 . This metamodel defines the concepts of classes (EClass) having references (EReference), attributes (EAttribute), and operations (EOperation). Metamodels are corner-stones of various meta-modeling activities that require a good understanding of the metamodels or parts of them. As illustrated in Figure 2, the meta-modeling conventions promote a 2D class diagram representation, close to the UML class diagram, to represent metamodels graphically. Models, conforming to their metamodel, can be manipulated by model transformations for various purposes (e.g. code generation). We motivate the need for integrating slicing-based interactive visualization features within graphical modeling tools based on the following common scenario. In an illustrative purpose, this scenario is based on the UML metamodel. Our approach, however, is dedicated to any large metamodel. Scenario. A modeler has to write a model transformation that generates Java code from UML models. The modeler has already a rough idea of main classes of the UML metamodel required for the transformation. These classes include: Association, Class, Package, Parameter, Property, and Operation. However, before writing the transformation, the modeler needs to have a clear and precise understanding of how these classes are organized within the UML metamodel and identify the properties and operations required for the transformation. To acquire this understanding, the modeler visualizes the UML metamodel using, for example, EcoreTools of EMF. The visualization of the whole UML metamodel is not a great help to her: as illustrated in Figure 1, the UML metamodel is overcrowded because of its 246 classes and 769 relationships. Yet, the modeler navigates and explores the UML metamodel to identify precisely classes and elements (properties and operations) required for her transformation. The following tasks are examples of such a process of navigation and exploration:

Task 1. The modeler uses the physical zoom of the editor to focus on classes related to Class. Since all the classes directly linked to Class do not appear, and a high number of relationships are tangled, the interest of this view is limited for the modeler. Zooming out again will gather too many classes and the view will still be unreadable such as in Figure 1.

Task 2. The modeler explores the inheritance relationships of Class to see all elements this class inherits. However, this task is quite difficult because of the tangled relationships and the high number of classes that hinder the visibility. Moreover, the multi-inheritance of several UML classes complicates the navigation within the inheritance tree of Class. For example, the inheritance tree of Class is composed of 17 inheritance relations. To get all the inherited properties of Class, the modeler needs to navigate through each of these classes.

Task 3. The modeler wants to obtain a reduced view of the UML metamodel that contains only classes relevant for her transformation. The modeler hides irrelevant metamodel elements using the filtering and navigation capabilities of EcoreTools. For instance, the filter Hide Selection enables the modeler to hide all the selected elements. After having hidden one by one the 216 classes of the metamodel not concerned by the transformation, the modeler finally obtains a subset of the UML metamodel that only contains the 30 relevant classes for her transformation.

IV. RELATED WORK

Metamodels are represented graphically using 2D class diagrams, close to the UML class diagram notation. So, research works on visualizing UML class diagrams or classes are related and could help to perform the previous scenario. Various works have been conducted on layouts to propose new algorithms for minimizing crossing relations [START_REF] Seemann | Extending the Sugiyama algorithm for drawing UML class diagrams: Towards automatic layout of object-oriented software diagrams[END_REF], [START_REF] Gutwenger | A new approach for visualizing UML class diagrams[END_REF]. Different guidelines for drawing class diagrams have also been proposed [START_REF] Eichelberger | Guidelines on the aesthetic quality of UML class diagrams[END_REF]. Several research works proposed to represent class models differently than using class diagrams, such as the class blueprint [START_REF] Ducasse | The class blueprint: Visually supporting the understanding of classes[END_REF]. Our work, however, focuses on supplementing standard metamodel editors with interactive visualization techniques. Also, we keep the focus on the class diagram representation promoted and widely-used within the MDE community. Complementary to our work, techniques have been proposed to visualize large UML class diagrams based on focus+context techniques [START_REF] Kagdi | Onion graphs for focus+context views of UML class diagrams[END_REF], [START_REF] Frisch | Off-screen visualization techniques for class diagrams[END_REF]. One difference compare to these works is our use of a language for defining model slicers. It aims at easing the development of several visualization features to be integrated into metamodel editors.

Reducing the amount of visible data to a subset of interest using filters and zooms have been already proposed for graph visualization [START_REF] Kumar | Browsing hierarchical data with multi-level dynamic queries and pruning[END_REF], [START_REF] Christian | Fisheye tree views and lenses for graph visualization[END_REF], [START_REF] Plaisant | Spacetree: supporting exploration in large node link tree, design evolution and empirical evaluation[END_REF]. In our work, we consider the structural concepts defining metamodels (composition, inheritance, etc.) to build the interactive visualization techniques.

Regarding MDE activities, research works have been proposed to ease the development of model visualizers and their layout [START_REF] Fuhrmann | Taming graphical modeling[END_REF], or to use gestures within modeling editors [START_REF] Scharf | Dynamic injection of sketching features into GEF based diagram editors[END_REF]. Our work follows this trend that aims at easing the development process of modeling editors and completing them with advanced interactive navigation features.

V. SLICING-BASED TECHNIQUES FOR INTERACTIVELY VISUALIZING LARGE METAMODELS

A. On the benefits of model slicing to build filtering features Ideally, the modeler, involved in the previous scenario, would have preferred to obtain the views in a more straightforward way instead of astutely combining the editor's filtering and navigation capabilities. If the editor had provided a filtering capability to show only classes directly linked to a selected class, Task 1 might have been easier. A similar filtering capability for the inheritance relationships might have eased Task 2. Regarding Task 3, a more complex filtering capability that combines the two previous ones might have also been useful for the modeler.

Model slicing is a model comprehension technique inspired by program slicing. The model slicing process involves extracting a subset of model elements that represent a model slice. The model slice may vary depending on the intended purpose. For example, when seeking to understand a large metamodel, it may help to extract the sub-part of the metamodel that includes only the dependencies of a particular class.

In our previous work [START_REF] Blouin | Kompren: Modeling and generating model slicers[END_REF], [START_REF]Modeling model slicers[END_REF], we proposed Kompren, a domain-specific language to define model slicers. A model slicer expressed with Kompren refers to a set of classes and relations from the metamodel under study. Instances of the referenced classes and relations will be sliced (i.e. extracted) from the input model. Listing 1 gives an example of a Kompren slicer. This slicer aims at slicing models of the Ecore metamodel (depicted in Figure 2). It selects several classes, references, and attributes of this metamodel to be sliced. This slicer is fully described in the next sub-section. After being manually specified by developers, a Kompren model slicer is compiled as Java code to be integrated in a Java program as a library. The execution of such an executable slicer program takes as input a model (here an Ecore model), instance of the input metamodel, and slicing criteria. Slicing criteria are model elements from the input model (here elements of an Ecore model) that provide the entry point for extracting a model slice. The slicing process visits all the elements specified in the model slicer starting from the slicing criteria. When visited, an element is sliced (i.e. extracted). In our case of metamodel visualization, it means that the sliced elements are displayed while the rest is hidden. This process permits to define dynamic filtering features to explore large metamodels, as detailed in the next sub-section.

B. Explen: a Kompren-Based Metamodel Visualization Tool

We developed a 2D metamodel visualizer in Java, called Explen, embedding dedicated interactive visualization techniques we developed using Kompren: we defined the model slicer described in Listing 1. Then, it has been integrated into Explen as the visualization engine. So, when users use Explen's features, described in this section, this slicer is called to perform a slicing and notify Explen about the metamodel elements to hide or show.

Semantic zoom. The physical zoom is supplemented with a semantic zoom that shows different metamodel elements depending on the zoom level. When zooming out at 50% the attributes, operations, and roles are no more displayed. The goal of this feature is to lighten or complete the amount of displayed information when visualizing at a given zoom level. This semantic zoom also works thanks to the model slicer depicted in Listing 1. Explen also provides the following dynamic filters to be applied on selected classes. The super and lower inheritance filters. They show the super or lower inheritance tree of the targeted class. These two filters can be parameterized with one option, the radius effect. When activated with a given value greater than 0, this option shows the classes in relation with the targeted class by a distance lower than or equals to the radius value. For instance, when the radius equals 1, only the direct classes of the targeted class are displayed. When set to 2, only these direct classes and their respective direct classes are shown. This option permits to reduce the number of classes shown in the view. For instance, the goal of the task 2 is to get all elements of a class (i.e., inherited and intrinsic properties, and operations). The modeler performs this task by getting the hierarchical tree of Class as depicted in Figure 3. Due to constraints on space, the classes' operations have been hidden, and the classes have been re-layouted manually to reduce the spacings.

Element

The slicing filter. It hides classes not in relation (inheritance or references) with the targeted class. This filter has three options that can be combined. The first option slices composition references only. The second option slices references having their minimal cardinality greater than 0 only. The third option is the radius parameter. For instance, the task 3 consists of showing only classes in relation with the UML class Class. This task can be performed using the Explen's slicer. To show only classes closely related to the class Class, the radius is set to 3. We also configure the slicer to consider composition references only. Then, the slicer is applied on the class Class and the classes not sliced are hidden. The flattening filter. The super hierarchy of the targeted class is removed to move into this last all its inherited attributes and relations. To perform the task 2, the modeler can also flatten this hierarchy to put in Class all the properties and operations of its super-classes. Figure 6 shows the result of the flattening of Class. All the super-classes of Class have been removed while their properties and operations have been moved into Class. The filters can also be successively combined. For instance, the goal of the task 1 is to show classes in direct relationship with Class. The modeler can accomplish this task with our viewer by restricting the radius effect of the slicer using the user interface: when the radius effect is set to 1, only classes in direct relationship with the sliced class are shown. Figure 6 also illustrates such successive combinations where the flattening filter is followed by a slicing of Class parameterized with a radius of 1. Users can apply these filters by right-clicking on a class to display a piemenu (Figure 5). The buttons of this menu permit to customize and apply filters on the targeted class used as a slicing criterion. These filters (super and lower inheritance, slicing, and flattening) have been developed using Kompren with the slicer given in Listing 1 and integrated into our Java application Explen as a visualization library. Since the visualized metamodels are defined using the Ecore meta-metamodel (Figure 2), the developed model slicer is based on this last (line 2). These filters work when applied on a selected class. The slicing criteria of the model slicer are classes (EClass, line 3). All the classes of type ENamedElement (line 5) are sliced. The references that the slicer goes through during the slicing process to extract instances of ENamedElement are defined from the line 8 to 12. The reference eSuperTypes is used to extract both the super and lower inheritance tree of a given class (lines 8-9). The keyword option identifies the corresponding sliced element as optional. This feature is used to define in a single model slicer, multiple filtering features. The reference eStructuralFeatures (line 10) defines the references and the attributes of a class, while eOperations (line 11) refers to their operations. The reference eType (line 12) is considered in our case as the targeted class of a reference. The sliced class EStructuralFeature is supplemented with a constraint (line 7). Constraints are optional conditions that must be respected to trigger the slicing of the element targeted by the condition. In our case, this constraint permits to slice references having a minimal cardinality greater than 0. It is used by the slicing filter that users can parameterize through the user interface. Finally, a radius is defined on the class EClass (line 4) as a parameter of lower/super inheritance and slicing filters.

Fig. 1 .

 1 Fig. 1. Bird view of the UML metamodel using EcoreTools (246 classes and 769 relationships)

Fig. 2 .

 2 Fig. 2. An example of metamodel: an excerpt of the Ecore metamodel

Fig. 3 .

 3 Fig. 3. The super inheritance tree of the UML class Class

Fig. 4 .

 4 Fig. 4. Slicing the UML metamodel using the class Class as input and parameterized with a radius of 3 and by slicing composition references only

Fig. 5 .

 5 Fig. 5. The piemenu activated by clicking on a class to apply filters.

Fig. 6 .

 6 Fig.6. Flattening of the UML class Class followed by a slicing parameterized with a radius of 1

  Listing 1. The Kompren model slicer used for visualizing metamodels

	1 slicer MetamodelSlicer {
	2	domain: "org.eclipse.emf.ecore/model/Ecore.genmodel"
	3	input: EClass
	4	radius: EClass
	5	slicedClass: ENamedElement
	6	slicedClass: EStructuralFeature feat
	7	constraint: card1 [[ feat.lowerBound>0 ]]
	8	slicedProperty: EClass.eSuperTypes option
	9	slicedProperty: EClass.eSuperTypes option opposite(subTyp)
	10	slicedProperty: EClass.eStructuralFeatures option
	11	slicedProperty: EClass.eOperations option
	12	slicedProperty: ETypedElement.eType
	13 }

VI. CONCLUSION AND FUTURE WORK

In this work, we promote the use of model slicing techniques to build visualization techniques dedicated to metamodels. We implemented a metamodel visualizer, called Explen. The Explen's visualization features were developed using Kompren, a domain-specific language for defining model slicers. We show how to develop different kinds of filters using Kompren to improve the understandability of metamodels.

In our future work, we will conduct an empirical study to assess the benefits of the proposed approach when doing metamodeling tasks involving metamodels. We also think that this approach can be adapted to UML class diagrams.

Comment