Christophe Tournier
email: tournier@lurpa.ens-cachan.fr

Emmanuel Duc
email: duc@lurpa.ens-cachan.fr

A surface based approach for constant scallop height tool path generation

Keywords: 3-axis milling, free-form surfaces, ball endmill, machining surface, tool path, scallop height

The machining of sculptured surfaces like molds and dies in 3-axis milling relies on the chordal deviation, the scallop height parameter and the planning strategy. The choice of these parameters must ensure that manufacturing surfaces respect the geometrical specifications. The current strategies of machining primarily consist in driving the tool according to parallel planes which generates a tightening of the tool paths and over quality. The constant scallop height planning strategy has been developed to avoid this tightening. In this paper, we present a new method of constant scallop height tool path generation based on the concept of the machining surface. The concept of the machining surface is exposed and its use to generate constant scallop height tool paths. The approach is confronted with existing methods in terms of precision and in particular its aptitude to treat curvature discontinuities.

Introduction

The machining of sculptured surfaces like molds and dies in 3 or 5-axis end milling requires the construction of successive tool paths and their juxtaposition according to a machining strategy. The machining strategy relies on the choice of a tool driving direction and two discretization steps, the step length along the path or chordal deviation (longitudinal step) and the cutter path interval or scallop height (transversal step). The tool path is then made of a discrete set of points representing the successive positions of the tool centre which will enable it to cover the surface. If the numerical control unit can read and interpret tool paths expressed in a polynomial, canonical, B-spline or Nurbs format, the tool path consists of curves respecting the chordal deviation criterion.

The choice of the chordal deviation and the scallop height parameters must lead to the realization of manufactured surfaces respecting the geometrical specifications of form deviation and surface roughness [START_REF] Lartigue | Machining of free-form surfaces and geometrical specifications[END_REF]. For a given part, the use of High Speed Milling (HSM) makes it possible to increase the number of tool paths, therefore to reduce the scallop height, without increasing machining time [START_REF] Schulz | High-speed milling of dies and moulds, cutting conditions and technology[END_REF]. However, the current strategies of machining primarily consist in driving the tool according to parallel planes, which does not optimize the rate of material removal. Along a tool path, the variations of the normal orientation on the surface in the perpendicular plane to the tool path generate a tightening of the tool path in its totality. This tightening increases machining time and creates over machining in some areas (Figure 1).

In order to increase the quality and the speed of machining, we propose to exploit the constant scallop height planning strategy. This strategy generates uniform scallops on the surface and ensures a better coverage of the surface by tool path. The narrowing of successive paths obtained with other strategies can be removed.

In the literature, few articles deal with the generation of constant scallop height tool paths for 3-axis milling with ball endmill [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] [4] [START_REF] Lin | Efficient tool-path planning for machining free-form surfaces[END_REF]. Furthermore these methods are quite similar. Tool paths are planned in the parametric space and the two first fundamental forms are used to evaluate the surface properties at the considered point.

In this paper, we use a new method of constant scallop height tool path generation based on the concept of the machining surface [START_REF] Duc | Usinage des formes gauches, contribution à l'amélioration de la qualité des trajectoires d'usinage[END_REF] [START_REF] Duc | A new concept for the design and the manufacturing of free-form surfaces: the machining surface[END_REF]. The machining surface enables us to consider the tool path as a surface and not anymore as a set of points (linear interpolation) or a set of curves (polynomial interpolation). Every curve onto the machining surface is a potential tool path which machines the surface without collision.

Given a machining surface, the tool path generation consists in choosing a set of curves belonging to the surface. The knowledge of this surface gives us more elements to precisely plan the relative position of these curves.

In the continuation of the article, the concept of the machining surface is presented.

Following its use to generate constant scallop height tool paths. The approach is then confronted with the existing methods and in particular its aptitude to treat curvature discontinuities on the surface.

The concept of the machining surface

The concept of the machining surface has been developed to improve the quality of the machined surfaces by associating a surface representation to the tool paths. First of all, the qualitative profits come from the integration of the functional constraints of design in the construction of the machining surface so that the machined surface respects the design intent. From a tool path generation point of view, the improvements come from the continuous representation of the tool path, contrary to the conventional approaches where the tool path is a discrete representation.

General definition of the machining surface: the Machining Surface is a surface including all the information necessary for the driving of the tool, so that the envelope surface of the tool movement sweeping the MS gives the expected free-form [START_REF] Duc | Usinage des formes gauches, contribution à l'amélioration de la qualité des trajectoires d'usinage[END_REF].

Considering each tool geometry and for each type for machining (3 or 5-axis) in endmilling or in flank-milling, a specific definition of the machining surface is proposed [START_REF] Duc | A new concept for the design and the manufacturing of free-form surfaces: the machining surface[END_REF]. In 3-axis end-milling, the definition of the machining surface corresponds to the definition of general offset surface. Since we use the ball endmill in this article, the machining surface is the traditional offset surface.

The tool path generation using offset surfaces has already been the object of numerous papers [8][9]. Among the problems encountered in the tool path generation using offset surfaces, the most constraining are the problems of loops or self intersections and of precision [START_REF] Farouki | The approximation of non-degenerate offset surfaces[END_REF] [START_REF] Maekawa | Computation of self intersections of offsets of Bezier Surface Patches[END_REF]. The problem of loops comes when using a tool which radius is larger than the smallest concave curvature radius of the surface. In order to be free from loop problems, we will consider tools whose radius is smaller than the smallest concave radius of curvature of the surface to be machined. This appears coherent within the framework of finishing milling used to generate constant scallop height tool paths. The problem of precision comes from the model of representation of offset surfaces. Indeed for most cases, it is not possible to model these surfaces by a parameterized NURBS surface without approximations. Therefore we will adopt in our study an implicit representation of the machining surface:

) v , u ( N R ) v , u ( S ) v , u ( S D M ⋅ + =
The advantage to use the machining surface to generate tool paths with constant scallop height, is that the distance between the driven point (the tool center) and the associated point on the scallop curve is constant and equal to the radius of the tool. In the methods where the point of contact between the tool and the surface (C C point) is driven, the distance between the C C point and the associated points of scallop varies all along the tool path.

The geometry of constant scallop height tool path

Let us consider two adjacent tool paths C i et C i+1 located onto the machining surface S M , offset surface of amplitude R of the design surface, and the surface of constant scallop height S Sh , offset surface of amplitude equal to the scallop height Sh. For each path, the envelope surface of the tool movement is a pipe surface the radius of which is equal to the tool radius and whose spine is the curve followed by the tool center. The scallop curve generated by the two paths is thus the intersection of the two pipe surfaces. In the case of a constant scallop height machining, this curve belongs to the surface of constant scallop height S Sh .

Practically, the previous geometrical problem can be uncoupled in two successive problems. The first problem consists in finding the scallop curve T i which is generated by the first path C i , where T i is the intersection of the envelope surface associated to C i , with the surface of constant scallop height S Sh (Figure 2). In the second problem, we build the adjacent tool path C i+1 which belongs to the machining surface S M starting from the scallop curve, so that the scallop curve T i is the intersection of the two pipe surfaces associated to C i and to C i+1 (Figure 3).

We show now that the curve C i+1 is the intersection of the machining surface with the pipe surface generated by the scallop curve T i .

For each point P i,j onto the scallop curve T i , the tangent t i,j to the curve T i is given by the cross product:

j 1, i j i, j i, + ∧ = n n t ( 1
)
with n i,j and n i+1,j the unit normals to the pipe surfaces at the considered point:

j i, j 1, i j 1, i j i, j i, j i, P CL P CL + + = = n n (2)
CL i,j and CL i+1,j are the tool locations which generate the point P i,j onto the scallop curve.

To a scallop point P i,j , we can associate a tool center point CL i+1,j on the path C i+1 with:

0 R P) , dist(CL j i, j 1, i j 1, i = ⋅ = + + t n ( 3
)
The searched path C i+1 , locus of the points CL i+1,j , thus belongs to a pipe surface of radius R whose spine is the scallop curve T i . Finally, the tool path C i+1 is the intersection of the previous pipe surface and the machining surface S M . Moreover, one will notice that the intersection of the pipe surface associated to T i , with the machining surface S M actually gives two curves which one is C i+1 and the other is C i , which is in agreement with (1) and ( 2). The construction of constant scallop height tool paths can thus be carried out by successive intersections between pipe surfaces and the machining and constant scallop height surfaces.

The methods developed by Suresh and Yang [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF], Sarma and Dutta [START_REF] Sarma | The Geometry and Generation of NC Tool Paths[END_REF], and Lin and Koren [START_REF] Lin | Efficient tool-path planning for machining free-form surfaces[END_REF] have in common the planning of tool paths in the parametric space while using fundamental forms to define differentials characteristics of the surface at the considered point. The initial path is sampled to calculate the points of the following path. This last one is then built by interpolation of calculated points. To be able to compare performances of our approach with existing methods and not to leave ambiguities on the way are generated the surface intersections, we suggest to generate successive tool paths point by point in the parametric space. The initial path is sampled and in every point we compute the associated scallop point as well as the corresponding point of the next tool path.

The first part of the problem is the search for the point P i,j element of the scallop curve when the tool is located on the point CL i,j on the initial path. The point P i,j is given by: (Figure 4)

{ } { } { } 1 S Sphere 1 P Plane Sh S P ∩ ∩ =
where Sphere S 1 is the active part of the tool and Plane P 1 the plane normal to C i passing through CL i,j .

The second part of the problem consists in determining the point CL i+1 of the following path from the scallop point P i,j . The point CL i+1,j is given by: (Figure 5)

{ } { }{ } 2 S Sphere 2 P Plane Sh S 1 i CL ∩ ∩ = +
where Sphere S 2 is the active part of the tool and Plane P 2 the plane normal to T i passing through P i,j .

Contrary to [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] and [START_REF] Lin | Efficient tool-path planning for machining free-form surfaces[END_REF] where the assumption is made that the problem is plane, i.e. that the point CL i+1,j is located in the plane perpendicular to C i passing through CL i,j , construction is done in two different planes. The point P i,j is in the P 1 plane and the point CL i+1,j in the P 2 plane. Actually, the problem is indeed plane because the three points P i,j , CL i,j et CL i+1,j are in the P 2 plane of normal t i,j (1)(2) but this plane is not known at the beginning of the construction.

Algorithms

In existing methods, it is necessary to associate a curve with each whole of calculated points C L to generate the following path. This is necessary to calculate the tangent vector to the tool path or to the scallop curve in order to define the study plane. This is not the case when using the method of the machining surface. The tangent vector is given by the cross product of the normals of both surfaces considered for intersection calculation [START_REF] Lartigue | Machining of free-form surfaces and geometrical specifications[END_REF]. In order to compare the methods, we thus propose to consider two versions of the method of the machining surface. We use the association of curves to compare the performances of the various methods (algorithm 1) and the other does not in order to study the impact of curve association on the behaviour of calculated paths (algorithm 2).

Computation of the tool positions CL i,j on successive path C i without association of curve Initial conditions : Design Surface S D : S(u,v) Constant Scallop height Surface S Sh : S(u,v) + Sh . n(u,v) Machining Surface S M : S(u,v) + R . n(u,v) For i = 1,n For j = 1,m Compute the tangent to the intersection curve between the pipe surface (C i ) and S Sh Compute the intersection point P i,j of S Sh , P 1j and Sphere S 1 End For j = 1,m Compute the tangent to the intersection curve between the pipe surface (Ti) and S M Compute the intersection point CL i+1,j of S M , P 2j and Sphere S 2 End End

The selected method for curve fitting is the interpolation by cubic B-spline curves.

We use a parameter setting proportional to the chord length [START_REF] Piegl | The Nurbs Book[END_REF]. Whatever the method, tool paths are calculated in the parametric space. In the case of algorithm 1, it is necessary to calculate the tangent to the current curve (scallop curve or tool path) so that the cutting plane (P 1 or P 2 ) is defined. The tangent vector t to a curve C(t) or C(u(t),v(t)) lying on the surface Φ(u,v) = S(u,v) + d . N(u,v) where d takes the value R or Sh is given by :

v u Φ (t) v Φ (t) u ⋅ + ⋅ = & & t (4)
where (t) u & and ⋅ (t) v & are the parametric tangent vectors and u Φ and v Φ the partial derivatives of the surface given by:

α N d α S α Φ ∂ ∂ ⋅ + = (5) α N ∂ ∂
is the curvature operator defined by:

β β α - = ∂ ∂ S b α N ( 6 )
Finally,

)) S b S (b d (S (t) v )) S b S (b d (S (t) u t v 2 2 u 1 2 v v 2 1 u 1 1 u ⋅ + ⋅ ⋅ - ⋅ + ⋅ + ⋅ ⋅ - ⋅ = & & (7)
b is the tensor of curvature or the second fundamental form.

Algorithms behaviour

At first, the methods are applied on a Nurbs surface delimited by two lines and two arcs of circle (Figure 6). It thus presents concave and convex areas and does not include any discontinuity of tangency or of curvature. The tool radius R is 10 mm and the specified scallop height is 0.001 mm.

The initial tool path is an isoparametric curve of the surface. Then, the initial tool path is sampled in points and points of the adjacent path are built one by one to define a first path and so on until the last tool path. Throughout this process we observe the propagation of the initial points, it is the traceability. We can thus visualise the tool center location or the surface contact point calculated before curves associations.

Indeed, the interpolation hides the behaviour of each algorithm.

The first test consists in comparing the proposed method with the method suggested in [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] and [START_REF] Sarma | The Geometry and Generation of NC Tool Paths[END_REF]. We pointed out that these methods use the association of curves inevitably. We thus use the method of the machining surface with association of curve (algorithm 1). The selected initial tool path is the isoparametric curve v 0 = 1/3, and the machining is done in the -y axis direction (Figure 7). The tool paths are represented by curves with the points used for computation. The progression is done from the top to the bottom and only one tool path on ten is represented for more clearness. We notice first of all that the three curves diverge progressively with machining. Curves generated by Suresh & Yang [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] are those which present the greatest variation in comparison to the others. In their approach, the problem is regarded as plane and one passes from one path to the other without passing by the scallop curve (what makes it the fastest method).

Moreover, the distance between successive tool paths is calculated in an approximate way. The two other methods are relatively close despite of a slight divergence.

The second test consists in studying the influence of curve association on the calculated tool paths (Figure 8). The two versions of our method are compared. It is noticed that the interpolation largely influences the results. Although tool paths are very similar, points position calculated with both methods vary. This is explained by the fact that the interpolation modifies the direction of the tangent vector to the curves at the calculated points, but does not modify the distance between two adjacent tool positions. Adjacent points are not evaluated in the correct direction. We could have introduce tangency constraints in the interpolation scheme but it wouldn't have been representative of the possibilities offered by the other methods.

Moreover, differences between tool paths are found on the resulting scallop height. Let us take the example of the difference between the tool paths generated by the method [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] and those generated with the method of the machining surface without association of curve (Figure 7). At the end of 100 tool paths, the distance between the ways is approximately 2 mm. If one considers that the drift is constant progressively with the construction of the tool paths, it represents approximately 20 µm (7%) of error between two consecutive tool paths, that is to say an error on the scallop height of 0,15 µm (15%) (Figure 9).

Behaviour on curvature discontinuities

We study in this part the treatment of curvature discontinuities. Indeed, the existing methods make the assumption that the surface curvature is constant around the considered point. This is not a problem during the machining of a B-spline surface made up of only one patch because this type of surface garantee the curvature continuity. But the majority of industrial parts are modelled with a multitude of patches connected in tangency and eventually with NURBS surfaces presenting curvature discontinuities. For example it is the case when we introduce blending radii. Let us consider the machining of a cylindrical surface along its generatrices whose profile (Figure 10) presents a curvature discontinuity at the point P 0 . The considered point is in the convex part of surface before P 0 and with the hypothesis of constant curvature, the adjacent tool location calculated is in P* 1 and not in P 1 as it should be. The resulting scallop height is thus not the expected one.

We thus study the behaviour of our algorithm and those developed in [START_REF] Suresh | Constant scallop-height machining of free-form surfaces[END_REF] and [START_REF] Sarma | The Geometry and Generation of NC Tool Paths[END_REF]. We consider the machining of a sphere lying on a plane with a connection in tangency (Figure 11). The surface consists of three surfaces: a half sphere (radius 10 mm), a portion of torus (radii 10 and 20 mm) and a plane. It presents two curvature discontinuities along the profile. The first one is located at the linking between the plane and the torus, the second between the torus and the sphere.

The adopted machining strategy is a machining according to the circular isoparametric from the outside of the surface towards the top of the sphere. Discontinuities are then well situated between two adjacent tool paths. We observe the scallop left by the tool at the two curvature discontinuities, with the three methods of tool path calculation.

It is also pointed out that for a given scallop height and a given tool radius, the tool paths are more spaced (resp. less) when the curvature is concave (resp. convex).

To compare the methods, the scallops left by the tool are built with the method of the Z-buffer. We build in the zone of interest a network of lines parallel to the z axis and laid out on a grid whose step indicates the precision. The step of the square grid is set to 0.025 mm. Then, we carry out the intersections between this network of lines and the envelope surfaces of the tool movement.

Results (Figure 12) show that methods that rely on constant curvature generate an abnormal scallop on the discontinuity, which is not the case for the method of the machining surface. At the junction between the torus and the sphere, results show a higher scallop than the others with the passage of discontinuity. The distance between paths is calculated as if the curvature were concave (torus) whereas it is convex (sphere). With a constant distance between path, the scallop height is larger on the sphere than on the torus. Between the planar zone and the torus, the scallops in errors are smaller. The algorithms calculate a distance between path as if the curvature were null (plane) whereas it is concave (torus). With a constant distance between paths, the scallop height is lower on the torus than on the plane.

The experimental results confirm our assumptions on the influence of the curvature approximations. Approaching a surface by its osculating sphere during the calculation of constant scallop height tool path does not allow the correct treatment of curvature discontinuities. Thus molds and dies containing many blending radii cannot be machined with such algorithms, plastic injected molds in particular. The method of the machining surface successfully the treats curvature discontinuities by leaving a scallop in accordance with the specifications.

Conclusion

The concept of the machining surface enables to adopt a new method to generate constant scallop height tool path which shows benefits. First of all, there is no needs to associate an interpolating curve to build consecutive tool paths. Without interpolation, the proposed method is more accurate than the other methods. It doesn't accumulate error from the beginning of the tool path calculation. Moreover, the method is characterized by its aptitude to treat curvature discontinuities. However, it should be noticed that these improvements increase computation time.

The concept of the machining surface also offers a framework to generate constant scallop height tool paths with flat-end or filleted endmills in 3-axis milling. But, whatever the method or the tool employed, it becomes necessary to tackle the problem of the tool path planning. Indeed, according to the initial tool path and the topology of the design surface, we have to extrapolate the tool paths close to the borders of the surface. Furthermore, the constant scallop height tool paths might contain loops. These loops could be eliminated but some tangent discontinuities would appear on the tool path.

Figure 1 :

 1 Figure 1: Tool paths tightening

Figure 5 :

 5 Figure 5: Discrete construction the tool path

Figure 6 : 1 Figure 7 : 2 Figure 8 :εFigure 9 :Figure 11 : Test surface 2 Figure 12 :

 61728911212 Figure 6: Test surface 1

  Figure 2: The geometry of constant scallop height tool path

	C i CL i,j C i n i+1,j T i R T i P i,j P i,j N i,j t i,j N i,j Pipe surface Machining surface S M Constant scallop height surface S Sh Design surface S D Machining surface S M Constant scallop height surface S Sh Design surface S D P1 C i Machining surface S M Machining surface C i S M t i,j S D S D surface surface Design Design C i+1 n i,j Pipe surface R C i+1 CL i+1,j Constant scallop height surface S Sh R P i,j CL i,j P2 t i,j S Sh τ i,j height surface R Constant scallop P i,j CL i,j CL i+1,j
	Figure 4: Discrete construction of the tool path
	Figure 3: The geometry of constant scallop height tool path


Eric Fouache
email: eric.g.fouache@orange.fr

Michel Magny

Amandine Bordon

Stéphane Desruelles

Cécile Oberweiler

Céline Coussot

Gilles Touchais

Petrika Lera

Anne-Marie Lézine

Lionel Fadin

Rébecca Roger

Palaeogeographical reconstructions of Lake Maliq (Korça Basin, Albania) between 14,000 BP and 2000 BP

Keywords: SRTM DEM, GIS, geoarchaeology, geomorphology, palaeoenvironment, Holocene, Albania

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Since the early 1990s, archaeological excavations carried out in the Korça basin in Albania, and especially in Sovjan, a tell occupied from the Early Neolithic (7990 cal BP -7060-6899 BC) until the Iron Age (2600 cal BP -822-671 BC), have confirmed that people settled and developed agriculture and stock-breeding as early as the Early Neolithic [START_REF] Korkuti | Neolithikum und Chalkolithicum in Albanien, Philipp von Zabern[END_REF][START_REF] Lera | Sovjan 1988[END_REF][START_REF] Lera | Travaux menés en collaboration avec l'École française d'Athènes en 1995. Sovjan (Albanie)[END_REF][START_REF] Touchais | L'habitat préhistorique lacustre de Sovjan (Albanie) : dix ans de recherches franco-albanaises (1993-2003)[END_REF]. This is the so-called "Podgorie culture" [START_REF] Kobas | Korça Basin Archaeological Survey Project, Preliminary Report for the season 2005[END_REF][START_REF] Korkuti | Neolithikum und Chalkolithicum in Albanien, Philipp von Zabern[END_REF][START_REF] Prendi | Le Néolithique ancien en Albanie[END_REF]. The Northern area of the basin was occupied by Lake Maliq until drainage works at the end of 1950s. The lake's surface area varied between a minimum of 40 km 2 during periods of low level to a maximum of 80 km 2 during high stands [START_REF] Fouache | Man and environment around lake Maliq (southern Albania) during the Late Holocene[END_REF]. From the Early Neolithic to the Early Iron Age, and especially during the Early/Middle Bronze Age transition (around 3800 cal BP -2310-2042 BC), the nearby lake shore was occupied by numerous settlements (Fig. 1) such as Maliq, the only "palaffitic" site studied in the basin [START_REF] Prendi | La civilisation préhistorique de Maliq[END_REF] and Sovjan, a lakeside site [START_REF] Touchais | L'habitat préhistorique lacustre de Sovjan (Albanie) : dix ans de recherches franco-albanaises (1993-2003)[END_REF].

In order to ascertain more detailed information on other settlements and to establish a model of human settlements around Lake Maliq, the French-Albanian archaeological team undertook land surveys around the lake. As part of these surveys, we undertook reconstructions of Lake Maliq for specific periods; namely for 14000 cal BP, the Mesolithic (around 9000 cal BP -8781-8542 BC), the Early/Middle Bronze Age transition (around 3800 cal BP -2310-2042 BC) and the Iron Age (2600 cal BP -822-671 BC). These reconstructions were established using GIS and DEM including geological and new palaeoenvironnemental and archaeological data. In addition, these reconstructions allow us to discuss the influence of Holocene climatic variability on fluctuations in the palaeo-levels of Lake Maliq.

Regional setting

Geology and geomorphology

Lake Maliq lies in the north-western part of the Korça basin, a graben valley, asymmetric in shape with a much higher scarp to the east (Fig. 2), located at 818 m a.s.l. and surrounded by highlands which reach 2028 m (Mali Thatë -Fig. 1). Limestone and ophiolite occupy the east of the basin, while molasses only outcrop to the west. While the nearby lakes of Prespa and Ohrid are permanent lakes with a karst regime (a landscape on limestone rock through which groundwater percolates, with submerged poljes), the Korça basin, outside the karst area, is drained by the river Devoll.

Tectonic activity during the Quaternary [START_REF] Tagari | Tectonique polyphasée plio-quaternaire en Albanie orientale (région de Korça-Pogradeçi)[END_REF] isolated the Korça graben within its present geological borders. However, the neotectonic subsidence did not exceed 0.15 to 0.20 mm y -1 [START_REF] Dufaure | Tectonics and geomorphological evolution: the example of the Korça basin (Albania)[END_REF] in the centre of the plain and cannot alone account for the substantial variations in the lake level.

Climate and vegetation

The local climate is characterized by annual rainfall averaging 800-1000 mm with maxima in winter (75-100 mm), and temperatures varying from 23°C to 25°C in July to 2°C to 5°C in January. The present-day vegetation is of the sub-Mediterranean type with an altitudinal distribution of the plant communities. The lower mountain slopes, up to about 1200 m a.s.l., are dominated by mixed deciduous forests with Carpinus orientalis, Acer monspessulanum, Pistacia terebinthus, Fraxinus ornus and Phillyrea latifolia. The upper slopes are covered by oak forests where Quercus trojana, Q. frainetto, Q. cerris may be locally associated with Pinus leucodermis, Juniperus excelsa, J. foetidissima and Aesculus hippocastanum. Beech woods, with Fagus moesiaca, Abies alba and Abies borisii-regis, are found above the oak forests, up to 1800 m a.s.l. Then, above approximately 1800 m a.s.l., sub-alpine moors and grasslands are present.

Holocene climatic variability

Quantitative estimates from pollen data [START_REF] Denèfle | A 12000-Year Pollen Record from Lake Maliq, Albania[END_REF] of monthly temperature and precipitation changes [START_REF] Bordon | Pollen-inferred Late-Glacial and Holocene climate in southern Balkans (Lake Maliq)[END_REF] suggest that, during the Oldest Dryas, from 16000 cal BP to 15100 cal BP, expansion of cold steppe dominated by Artemisia and Poaceae was related to low temperatures in both summer and winter, and annual precipitation totals lower than approximately 400 mm. Rainfall was 30 mm higher than today in average in summer and 60 mm lower in winter.

From 15100 cal BP to 12800 cal BP, during the Bølling/Allerød, steppes were progressively replaced by temperate deciduous forests in relation to temperate climate conditions close to modern values.

From 12800 cal BP to 11300 cal BP (Younger Dryas), a return of cold and dry conditions led to the wide expansion of steppes.

Then, during the first part of the Holocene, from 11300 cal BP onward, remarkably stable environmental conditions prevailed in the Korça basin with vegetation dominated by elements characteristic of temperate deciduous forests, and climate conditions similar to the present day.

A short-lived arid event punctuated this overall temperate period at 8200 cal BP (7445-7064 BC). The climate was characterized by a decrease in annual rainfall of 250 mm compared to the mean Holocene value and low temperatures responsible for the degradation of the forest at Maliq.

From 1000 cal BP to the present, the climate reconstructions show large variability and major oscillations both in temperature and precipitation.

Climate conditions during the Holocene at Maliq were not as cool and moist than those recorded elsewhere in the Mediterranean area [START_REF] Cheddadi | The climate of Europe 6000 years ago[END_REF][START_REF] Huntley | July temperature in Europe from pollen data, 6000 years before Present[END_REF][START_REF] Masson | Mid-Holocene climate in Europe: what can we infer from PMIP model-data comparisons?[END_REF][START_REF] Roberts | The tempo of Holocene climatic change in the eastern Mediterranean region: new highresolution crater-lake sediment data from central Turkey[END_REF][START_REF] Sadori | The postglacial record of environmental history from Lago di Pergusa, Sicily[END_REF], probably in relation with the steep altitudinal gradient in the basin. The reconstructed temperatures record high amplitude changes, between -5°C and 10°C from 8200 cal BP (7445-7064 BC) to 1000 cal BP (ca 1000 AD) (Fig. 3), probably enhanced by the topography of the Korça basin. There is a clear difference in the annual distribution of rainfall between warm and cold phases with a maximum in summer during the cold phases (Older and Younger Dryas, 8200 BP event) and a minimum during the temperate phases (Bølling, Allerød, Holocene). The seasonality of precipitation thus appears to be a crucial climatic parameter to consider in the Mediterranean palaeo-climate reconstructions, as observed in other place in the Near-East (Bar [START_REF] Matthews | Middle to Late Holocene (6,500 Yr. Period) Paleoclimate in the Eastern Mediterranean region from stable isotopic composition of Speleothems from Soreq Cave, Israel[END_REF][START_REF] Bar-Matthews | Sea-land isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implications for paleorainfall during interglacial intervals[END_REF][START_REF] Bar-Matthews | Speleothems as paleoclimate indicators, a case study from Soreq cave located in the Eastern Mediterranean region[END_REF][START_REF] Bookman | Late Holocene lake-levels of the Dead Sea[END_REF][START_REF] Enzel | Late Holocene climates of the Near-East deduced from Dead Sea-level variations and modern regional winter rainfall[END_REF][START_REF] Frumkin | The Holocene History of Dead Sea Levels in[END_REF][START_REF] Stevens | Timing of atmospheric precipitation in the Zagros Mountains inferred from a multi-proxy record from Lake Mirabad, Iran[END_REF].

Methods

Here we use catchment geomorphological mapping techniques, lithostratigraphy description and palynological analyses from cores taken along a 150 m long transect (from the archaeological site of Sovjan to the centre of the palaeo-lake) to characterize the sedimentary deposits in the Korça basin to reconstruct palaeoenvironmental changes. The aim of this study is to complement the archaeological excavations of the Korça Basin and to derive greater knowledge and understanding of human-environment interactions in this part of Albania. This requires a combined approach of natural and cultural dynamics through time [START_REF] Touchais | La dynamique des occupations de bord de lac dans le Sud-Ouest des Balkans : l'exemple de Sovjan, bassin de Korça (Albanie)[END_REF]. Attention is paid here to fluctuations of the lake level in the Korça basin and their impact on human settlements, in particular on the tell of Sovjan, continuously excavated and studied since the 1990s.

In order to achieve this, we have embedded archaeological, geological, topographic and DEM data into a GIS model.

DEM creation using SRTM data

Topographic data used for the study of the Korça Basin come from NASA SRTM3 data (Shuttle Radar Topography Mission -Fig. 4). In spite of the 30 m spatial resolution [START_REF] Farr | The Shuttle Radar Topography Mission[END_REF], these data were preferred as opposed to topographic information provided by the Albanian maps: in our study area, the most precise topographic maps (1:25 000 scale), published in 1982, have 5 m interval contour lines in plain. Because this interval thus does not allow us to discriminate the topography of the centre of the Lake Maliq basin, SRTM data were used. The quality of SRTM data was controlled with differential GPS (DGPS) measurements on two transects (E/W and N/S) along the plain of the Korça Basin. These two types of topographic data are based on the WGS84 projection system associated with the EGM96 geoïd. On average, the heights of the cartography resulting from SRTM data are 1.80 m higher than the altitudes provided by the DGPS. This difference appears to be in conformity with that usually observed in flat regions (<2m - [START_REF] Rodriguez | An assessment of the SRTM topographic products[END_REF]. SRTM data were added in the GIS of the Korça Basin, created with the ESRI ArcGIS 9.1 software. DEM and contour lines were created with the 3DAnalyst extension.

Geological and palaeoenvironmental data integration into the GIS to reconstruct the palaeo-topography of the Korça basin

Unpublished data (Fig. 5) from the geological service in Korça (101 logs obtained in 1974 by core-drilling, E/W and N/S profiles) allowed us to reconstruct the subsurface geometry of Lake Maliq, and in particular the bottom of the basin before its infilling by peat. This reconstruction was necessary, because the elevation of the low lake levels is lower than the current minimal height of the Korça basin. Heights of the palaeotopography of the plain of the Korça Basin, interpreted using the core log, were integrated into the GIS.

Palaeoenvironmental analyses on cores to establish chronostratigraphy of the palaeo-lake Maliq

Past water level fluctuations of Lake Maliq were reconstructed using changes in the lithology [START_REF] Digerfeldt | Studies on past lake-level fluctuations[END_REF][START_REF] Magny | Holocene fluctuations of lake levels in west-central Europe: methods of reconstruction, regional pattern, palaeoclimatic significance and forcing factors[END_REF] observed along the 150 m long core transect (Fig. 6). Organic deposits (peat, anmoor) characterize overgrowing processes and littoral mires. Grey-blue to green-blue silt and silty-clay deposits include freshwater mollusc tests and correspond to sedimentation in open deeper water. The upper brown silt layer which overlay the peat deposits in cores K4 to K10 (above level ca 815 m a.s.l.) corresponds to lake deposits mixed with substantial detritic inputs (erosion due to an intense period of human impact in the catchment area during the last two millennia).

The pollinic studies carried out in the Korça Basin [START_REF] Denèfle | A 12000-Year Pollen Record from Lake Maliq, Albania[END_REF][START_REF] Fouache | Man and environment around lake Maliq (southern Albania) during the Late Holocene[END_REF] show a continuous and high anthropogenic impact on the vegetation from 4500 cal BP (3300-3000 BC), with phases of higher impact towards 3000-2500 cal BP (1400-1000 BC/800-450 BC) and towards 1500 BP (450-650 AD, corresponding to Late Antiquity and the beginning of the Middle Age).

The core transect provides a comprehensive stratigraphic section of the littoral sediment sequence, so that the geometry of the layers and the lateral variability of the lithological facies can be highlighted.

The ages of the lake level changes identified from the sediment sequence have been inferred from radiocarbon and archaeological dating [START_REF] Fouache | Man and environment around lake Maliq (southern Albania) during the Late Holocene[END_REF][START_REF] Touchais | La dynamique des occupations de bord de lac dans le Sud-Ouest des Balkans : l'exemple de Sovjan, bassin de Korça (Albanie)[END_REF]. Six 14 C measurements have been retained (table 1) and converted into calendar ages (cal BP) using calibration from Reimer et al. (2004). Thus, the estimation of the lake level fluctuations and the past positions of the water table were based on two lines of evidence as follows:

-Firstly, the lithology and the composition of sediment as illustrated in figure 6. It is assumed that (1) the depth data of the organic layers (peat) was in equilibrium with or ca 0.50 m above the mean water table, and (2) silt and silty-clay layers corresponded to at least 0.50 m-1 m water depth.

-Secondly, the altitude above sea level where the respective layers of deposits have been observed in the sediment sequence (Fig. 6).

Results

The sediment sequence of Lake Maliq allows us to distinguish a series of centennialscale high and low lake level events which punctuated the Holocene period (Fig. 10). In particular, the radiocarbon ages obtained in core K5 and K1 indicate that the first formation of peat in the southwestern shore area of Lake Maliq occurred between 9400 cal BP (8781-8542 BC) and 8100 cal BP . This peat deposition may reflect an overgrowing process or a lake level lowering, or it may have resulted from a combination of both processes. During this phase, corresponding to the end of the Mesolithic and the beginning of the Neolithic, the lake level was at ca 810-811.50 m a.s.l.

The upper part of the peat deposits, which accumulated before the formation of layer H, includes many wood fragments which indicates that the lake level was at ca 812-812.50 m a.s.l. between ca 6000 cal BP (5062-4830 BC) and 3800 cal BP (2310-2042 BC).

The deposition of the silty-clay layer H observed in cores K1, K2, K3 and K5 coincides with a highstand of the water table which may have reached 814.50-815 m a.s.l. between ca 4200 cal BP (2899-2637 BC) and 4000 cal BP (2843-2416 BC). This layer (observed in cores K1, K2 and K3) was contemporaneous with the development of the tell from the late Early Bronze Age to the Iron Age (ca 4000 cal BP-2600 cal BP (2843-2416 BC/822-671 BC). It was also synchronous with an accumulation of peat in cores K4 and K5. The water table probably stood below 814 m a.s.l.

The abandonment of the tell during the Iron Age (at around 2600 cal BP -822-671 BC) was followed by the deposition of a clay layer which overlaid the highest parts of the tell of Sovjan and marks a high lake level. The water table may have reached 816.50-817 m a.s.l.

During the Roman period, the lake level returned to a lower stand (less than 814-814.50 m a.s.l.) as indicated by the deposition of peat which commenced at ca 2000 cal BP (51 BC-72 AD). This low stand was followed by higher lake level conditions that resulted in the deposition of a 1 m-thick layer of lacustrine silt and erosive inputs (water table above 815.50-816 m a.s.l).

These lake level results were subsequently integrated into the GIS model which allowed us to propose four palaeogeographical reconstructions of the extension of Lake Maliq (Fig. 7) at stages when its level was high.

Discussion

The present day mean subsidence rate of the Lake Maliq basin is estimated between 0.15 and 0.20 mm y -1 [START_REF] Dufaure | Tectonics and geomorphological evolution: the example of the Korça basin (Albania)[END_REF]. Before the drainage works and especially prior the water abstraction, it was noticeably lower but the subsidence rate accounts for the thickness of the Holocene sediment.

The accumulation of peaty deposits, the thickness of which exceeds 4.50 m, suggests that the water table of Lake Maliq (latitude: 40°45'N; altitude: 818 m a.s.l.) was characterized by a progressive rise since the mid-Holocene. The rising millennial-scale trend contrasts with that reconstructed for the same period at Lake Xinias (latitude: 39°45'N; altitude: 500 m a.s.l. [START_REF] Digerfeldt | Reconstruction of Holocene lake-level changes in Lake Xinias, central Greece[END_REF], but it is in agreement with that established at Lake Accesa in Tuscany (latitude: 43°N; altitude: 157 m a.s.l. [START_REF] Magny | Holocene climate changes in the central Mediterranean as recorded by lake level fluctuations at Lake Accesa (Tuscany, Italy)[END_REF]. It may be a reflection of a possible NW-SE contrast in climate history during the Holocene in the Mediterranean area as suggested by [START_REF] Roberts | Stable isotope records of Late Quaternary climate and hydrology from Mediterranean lakes: the ISOMED synthesis[END_REF]. Nevertheless, it is also possible that, during the second half of the Holocene, anthropogenic forest clearances may have induced increasing erosion in the catchment area and, more particularly, may have been responsible for an accumulation of colluvial deposits in the outlet area [START_REF] Denèfle | A 12000-Year Pollen Record from Lake Maliq, Albania[END_REF][START_REF] Fouache | Man and environment around lake Maliq (southern Albania) during the Late Holocene[END_REF]. Such a subsidence rate (estimated between 0.15 and 0.20 mm y -1 ) can thus only partially explain such an important accumulation of peat. In addition, it is clearly too small to explain the relatively quick changes in lake level as observed at ca 4200 cal BP (2899( -2637 BC) BC) and between the Iron Age and Roman period (ca 2600 cal BP -2000 cal BP, corresponding to 822-671 BC/51 BC-72 AD).

These relatively abrupt changes are most probably attributable to climatic fluctuations (seasonal change in precipitation or temperature). Two of the distinct centennial-scale high lake level events can be related to large-scale climate changes [START_REF] Bordon | Pollen-inferred Late-Glacial and Holocene climate in southern Balkans (Lake Maliq)[END_REF][START_REF] Di Rita | Holocene drought, deforestation and evergreen vegetation development in the Central Mediterranean: a 5500 year record from Lago Alimini Piccolo, Apulia, southeast Italy[END_REF][START_REF] Drysdale | Late Holocene drought responsible for the collapse of Old World civilizations is recorded in an Italian cave flowstone[END_REF][START_REF] Magny | Possible complexity of the climatic event around 4300-3800 cal. BP in the central and western Mediterranean[END_REF][START_REF] Marchant | Rapid environmental change in African and South American tropics around 4000 years before present: a review[END_REF][START_REF] Van Geel | Archaeological and palaeoecological indications of an abrupt climate change in The Netherlands, and evidence for climatological teleconnections around 2650 BP[END_REF]:

-the first, between 4200-4000 cal BP (2899-2637 BC/2843-2416 BC) may have been a local expression of climate change dated to 4200 cal BP, -the second, around 2600 cal BP (822-671 BC) may be due to climate change dated to 2700 cal BP (896-795 BC). Thus, lake level data provided by this study appear to be an interplay between lake level rises and falls against tectonic subsidence of the basin allowing accommodation space for sediment deposition.

Our results do not permit us to conclude that the rise in the lake level was responsible for the abandonment of the site of Sovjan during the Iron Age. However, we may suggest that it did play a part in it. The higher lake levels, together with the knowledge of the thickness of the sediment, have allowed us to design a predictive map of the potential archaeological layers for the Neolithic and the Bronze Age (Fig. 8 and9). The preliminary results of the survey carried out in August 2008 show a reliable correlation between the location of the sites dating back to these periods and our reconstructions over the periods in question. However, they also show that the medieval sites dating back to the 8 th and 9 th centuries AD are all located slightly inward with regard to the lowest lake level we reconstructed. This shows that a very low lake level did exist at that time and that our palaeoenvironmental reconstructions need to be extended over the past 2000 years.

Conclusion

The regional study carried out around Lake Maliq demonstrates that, in order to assess correctly the surface archaeological potential as well as that of the Holocene sedimentary layers, it is necessary to take into account the variability of lake levels and of the associated sediments.

The integration of the geological and geomorphological data from these Holocene layers into a GIS and a DEM permits 3D modelling of the basin, a regular update of this model that easily integrates the new data, and provides synthetic maps of use to archaeologists and developers alike. In the long run, these maps also enable precise palaeogeographical reconstructions to be carried out.

Our research will continue towards relating higher lake levels to precise climatic events, towards comparing lakes Prespa and Ohrid on a regional scale but also making a palaeogeographical atlas of the areas around the lake from the Early Neolithic to the present day.

Acknowledgements

Many thanks are addressed to the French CNRS through the ECLIPSE project coordinated by A.-M. Lézine and E. Fouache, entitled "Variations climatiques et dynamique des écosystèmes au Sud des Balkans au cours du dernier cycle climatique".

The study was supported by the French-Albanian archaeological cooperative project, the French Archaeological School at Athens (Greece), the Archaeological Museum of Korça (Albania) and ARTEMIS AMS facilities in Saclay (France).

The authors warmly thank Dr. Cecile Fouache-Loire for the English improvement and the anonymous reviewer for its comments and suggestions.


Francois Bonnet

Clotilde Caillault

Keywords: Police, Racism, Social desirability, Speech, Discourse, Europe

The invader, the enemy within and they-who-must-not-be-named

Introduction

In most countries, social groups-often construed as ethnic groups-become the main suspects of police activity: African Americans in the United States, "Caucasians" (from the Caucasus) in contemporary Russia and Roma people in Continental Europe. They have been called "police property", the "dangerous classes", the "symbolic assailant", and so on. This article does not set out to demonstrate that these targeted minorities commit less or more crime than the majority, it is about how police officers talk about them in France, Italy and the Netherlands.

How people talk about race is a sensitive subject, because of the moral condemnation of racism. For instance, in the aftermath of the Stephen Lawrence inquiry, police organizations in the United Kingdom have prohibited racial slurs [START_REF] Foster | Assessing the impact of the Stephen Lawrence inquiry[END_REF]. Strict non-racist speech norms regarding race are a fact of life in much of the Anglophone world [START_REF] Eliasoph | Making a Fragile Public: A Talk-Centered Study of Citizenship and Power[END_REF][START_REF] Pollock | Colormute. Race Talk Dilemmas in an American School[END_REF]. The folk concept of "political correctness" has sought to capture the set of social norms that governs discourse about race [START_REF] Fairclough | Political correctness': The politics of culture and language[END_REF]. This issue is of special concern within law enforcement, as police officers are often suspected of engaging in profiling and discrimination (Reiner, 2010, pp. 128-131).

How do speech norms apply outside the Anglophone world? We know less about Continental Europe than we do about North America and the United Kingdom, where "political correctness" is a much-discussed notion. This is why the article examines France, Italy and the Netherlands. What is at stake here is the relation between speech norms and how police interact with minorities. Police-minority relations are a central topic in race research and raise questions of social justice [START_REF] Brunson | Young Black Men and Urban Policing in the United States[END_REF][START_REF] Carr | We Never Call the Cops and here is why: A Qualitative Examination of Legal Cynicism in Three Philadelphia Neighborhoods[END_REF][START_REF] Hasisi | Police Relations with Arabs and Jews in Israel[END_REF][START_REF] Sharp | To Serve and Protect? The Experiences of Policing in the Community of Young People from Black and Other Ethnic Minority Groups[END_REF]. This exploratory study is based on interviews with 55 police officers from France, Italy and the Netherlands. In these three countries, police officers are aware that displaying overt racism is not socially acceptable. Interviews show that there are vastly different speech norms governing acceptable race talk in the three countries. Specifically, we compare: how police use ethnic categories; how police anticipate accusations of discrimination; and how police theorize the over-representation of ethnic minorities in criminal activity.

Racism as a category of practice

In contemporary public space and social science, racism is the object of strong and nearuniversal disapproval. In the past twenty years, public opinion research in the United States has found fewer respondents willing to endorse racist views [START_REF] Schuman | Racial Attitudes in America: Trends and Interpretations[END_REF]. In many Western democracies, overt racist speech is publicly reviled and there are legal statutes criminalizing racist speech and discrimination, or aggravating punishment for hate crimes [START_REF] Bleich | The Freedom to be Racist? How the United States and Europe Struggle to Preserve Freedom and Combat Racism[END_REF]. Political parties -even those of the extreme right, whose appeal largely rests on racial resentment -vehemently object to being labeled as racist [START_REF] Mudde | Populist radical right parties in Europe[END_REF]. Within corporations, human-resources divisions have to care about diversity in the workplace [START_REF] Dobbin | Equal opportunity law and the construction of internal labor markets[END_REF]. In everyday life, this translates into a social world where people do not want to appear racist. This context leads to two intellectual routes. The first uses critical discourse analysis to reveal closeted racism. This is the project of Teun van Dijk (1992), implemented by, among others, [START_REF] Bell | Diversity in Everyday Discourse: The Cultural Ambiguities and Consequences of 'Happy Talk[END_REF], [START_REF] Bonilla-Silva | Rethinking Racism: Toward a Structural Interpretation[END_REF][START_REF] Bonilla-Silva | Racism Without Racists (Second Edition)[END_REF], [START_REF] Myers | Race Talk: The Perpetuation of Racism Through Private Discourse[END_REF] and [START_REF] Zamudio | From Traditional Racism to Liberal racism: Living Racism in the Everyday[END_REF], which aims to study discourse and to show how hesitations, contradictions, inconsistencies and nervous laughs are evidence of inner racism. Discourse analysis allows us "to delve beneath the surface of initial answers to reach the deep structure and cultural commonsense" (Bell and Hartmann, 2007, p. 898). A key assumption of these authors is that racism is a category of analysis (a scientific concept).

The second route rests on a different premise: following [START_REF] Brubaker | Beyond Identity[END_REF] and [START_REF] Wacquant | For an Analytic of Racial Domination[END_REF], it conceptualizes racism as a category of practice. Instead of looking for evidence of inner racism in people's speech patterns, this article sets out to compare how similar actors in three different countries speak about race and minorities, to document different speech norms around race talk. By comparing speech norms in France, Italy and the Netherlands, we are looking into different regimes of speech norms, and ultimately different conceptions of what is racist or not.

We answer two research questions. (1) Is there cross-national variation in speech norms? Openly racist speech has become deviant in Anglophone countries. What is the situation in Western Europe? We may hypothesize that different histories of race and migration may produce different speech norms. Societies with a longer history of racial relations (non-white immigration, colonial past and an involvement in slavery) may be more likely to develop stricter speech norms. (2) How important are speech norms? Speech norms may be interesting in their own right, but their practical consequences matter. In particular, is there a relation between speech norms and police-minority relations? Two competing hypotheses may answer this question. On the one hand, critical discourse analysis assumes that speech reveals deeper attitudes which, in turn, translate into practices. On the other hand, [START_REF] Waddington | Police (Canteen) Subculture. An Appreciation[END_REF] treats police speech as "expressive talk", e.g. disconnected from practices and largely irrelevant to the study of actual police-minority relations.

Research design: making use of the social desirability bias

To reveal speech norms, our methodological strategy is to make use of the social desirability bias. Social desirability means that respondents know that some attitudes or behaviors are more desirable than others, and they will tend to distort their answers to be perceived more favorably (Philips and Clancy, 1972). Social desirability bias has been used to explain why, depending on context, people over-or under-report their religiosity, income, party affiliations or achievements. Social desirability is usually perceived as a methodological obstacle, because it makes data less reliable. Scholars are thus looking for ways to "overcome" the social desirability bias [START_REF] Pager | Bayesian Bigot? Statistical Discrimination, Stereotypes, and Employer Decision-Making[END_REF][START_REF] Pager | Walking the Talk? What Employers Say Versus What They Do[END_REF] by utilizing participant observation [START_REF] Shapira | From the Nativist's Point of View. How Ethnography Can Enrich Our Understanding of Political Identity[END_REF], audit studies [START_REF] Pager | Walking the Talk? What Employers Say Versus What They Do[END_REF] or interviews [START_REF] Blauner | Black Lives, White Lives: Three Decades of Race Relations in America[END_REF].

Our research design is based on the assumption that we can make the social desirability bias work to our advantage in order to reveal regimes of speech norms [START_REF] Bonnet | How to Perform Non-Racism? Colorblind Speech Norms and Race-Conscious Policies among French Security Personnel[END_REF]. Interviews create an artificial setting where people have to manage social desirability concerns. In our case, how police talk about minorities, racism, profiling and discrimination reflects prevailing (but contextual) speech norms [START_REF] Bonnet | How to Perform Non-Racism? Colorblind Speech Norms and Race-Conscious Policies among French Security Personnel[END_REF]. We are not interested in what officers "really" or "privately" think: what matters to us is "what they are supposed to say to a stranger".

To demonstrate that speech norms are contextual, we have interviewed a total of 55 police officers and security personnel in three Western European countries: France, Italy and the Netherlands.

-32 police officers in France, two sites in the Paris region (second author, interviews in French). 6 respondents out of 38 were female, 7 were minority, and the respondents' mean age was 33. -12 officers in the Netherlands, two sites in the Amsterdam region (second author, interviews in English). One respondent was female and another one was minority, with a mean age of 33. -11 persons in Italy, two sites in the Milan region, including 4 police officers and 7 private security personnel (first author, interviews in Italian). All respondents were male, one was from a minority, with a mean age of 39.

We conducted research in two waves. In 2004, the first author did a comparative study of policing at four sites in France and Italy. In 2011, the second author did a comparative study of policing in France and the Netherlands, under the supervision of the first author. This article is based on the first author's Italian data and the second author's French and Dutch data.

Comparability is ensured because the two sites in each country are located in the largest urban area, which maximizes ethnic diversity; in each country, one site was located in a poorer, higher crime neighborhood than the other site. On each site, we received authorization to contact police officers in two precincts, and we interviewed as many volunteers as we could. This sampling method does not guarantee randomness, but was imposed by circumstances. We did not compensate respondents. We guaranteed confidentiality. Interviews took place at the precinct station and lasted from 45 to 90 minutes. Interviews in France and the Netherlands were recorded, transcribed and inductively coded (Glaser and Strauss, 1967) with the support of the Atlas.ti software. Respondents in Italy did not allow audio recording. The researcher took as many handwritten notes as possible during the interview, then completed the notes as soon as the interview was over, and transcribed the notes fully. We selected the quotes that said most eloquently what most other officers were saying.

In We have avoided discussing race overtly; we sought to avoid a situation where informants would have to articulate their folk theory of racism. We believe such research to be more likely to result in artifacts. We chose to let conversations organically develop towards criminal activity of minorities, so as to be able to document how police officers talk without being primed by our choice of words. Our research design works like a quasi-experiment; we ask the same questions to the same people, and we put them in a similar situation: that of speaking of race and crime, which should trigger the social desirability bias. Our findings are based on the contrast between how these similar people speak about race, racism and minorities in different countries.

Our sample of France, Italy and the Netherlands allows us to answer our first research question (variability of speech norms) because these countries are not Anglophone and each represents a different style of Western European society [START_REF] Arts | Three worlds of welfare capitalism or more? A state-of-theart report[END_REF][START_REF] Esping-Andersen | The Three Worlds of Welfare Capitalism[END_REF]. In this typology, Anglophone countries exemplify the residual welfare state.

France is representative of corporatist states alongside countries like Germany or Belgium.

Italy is representative of Southern European (Mediterranean) states like Spain or Greece. The Netherlands are representative of social-democratic states like Scandinavian countries.

Regarding our second research question (relation between speech norms and police-minority relations), the sample introduces two variables. One is the different colonial and immigration histories. France and the Netherlands have been colonial empires, deeply involved in the slave trade, and have been countries of immigration for decades-since the late 19 th century in France [START_REF] Weil | La France et ses étrangers[END_REF] and the 1950s in the Netherlands [START_REF] Vasta | From ethnic minorities to ethnic majority policy: Multiculturalism and the shift to assimilationism in the Netherlands[END_REF]. Italy is a case of more recent immigration, with Albanians, Romanians, Moroccans and Chinese immigrants arriving since the 1990s [START_REF] Pittau | Italia, paese di immigrazione : tra flussi regolari e irregolari[END_REF]. The other variable is racial tensions related to policing. The frequency of riots in France suggests that relations between minorities and the police are very poor (Body-Gendrot and Wihtol de [START_REF] Body-Gendrot | Police et discriminations raciales: le tabou français[END_REF][START_REF] Fassin | La force de l'ordre[END_REF]Open Society Institute, 2009;[START_REF] Pager | The Republican Ideal? Ethnic Minorities and the Criminal Justice System in Contemporary France[END_REF]. The Dutch and Italian cases are relatively less contentious.

This research design has limitations. First, the interviews were performed by French interviewers in France, Italy and the Netherlands, possibly putting Dutch and Italian respondents in a different position to that of French respondents. Dutch respondents were interviewed in English. We believe these limitations to be inconsequential, because other studies done by Dutch and Italian scholars in their respective countries point towards similar speech patterns (Dal Lago, 1999;[START_REF] Lago | La città e le ombre[END_REF][START_REF] Pakes | The politics of discontent: The emergence of a new criminal justice discourse in the Netherlands[END_REF][START_REF] Quassoli | Immigrazione uguale criminalità. Rappresentazioni di senso commune e pratiche organizzative degli operatori del diritto[END_REF]. Second, it has been difficult to gain access to Italian police officers, and our Italian data are based on a case study of plural policing, hence the presence of private security personnel. Because we have found public and private officers' speech patterns to be remarkably similar, and because our findings are coherent with Italian scholarship, we think that this limitation is manageable. Third, the unrepresentativeness of the sample prevents us from generalizing our findings. Systematic research with multiple sites across each country, and with a larger number of respondents, would certainly reveal regional variations in speech norms, and internal variations in the observance of speech norms. Yet, such a study would prove costly and difficult to organize, as police organizations, notably in France and Italy, are reluctant to cooperate with social research. Because of these limitations, we see this study as exploratory in design, aimed at formulating hypotheses to be tested systematically.

Ethnic categories as awkward and muted (France) or explicit and commonsense (Italy, Netherlands)

Before going into the specifics of how police officers from different countries discuss race and ethnicity, we may first inquire as to whether the mere fact of speaking about ethnicity is unproblematic or awkward. In this section, we document how using ethnic categories is uneasy in France, and how it is casual in Italy and the Netherlands.

French respondents categorically and adamantly deny that the very category of color, ethnicity or race may play a role in their police work. No matter how the subject is approached, respondents seem to feel personally attacked or judged, and become defensive.

French police officers are extremely concerned with anticipating and avoiding potential accusations of racism, and such a direct association of ethnicity with crime typically violates French speech norms. These speech norms are manifest when one considers the awkwardness with which French officers talk about ethnicity when they have to.

Question: Are foreigners subjected to more police stop-and-checks? I ask because there is a lot of debate about that in the Netherlands.

French police officer: Well no, not at all. Me, I do identity checks on request [abbreviation from legal lexicon], me, I check everyone, that's it. I can't stand it, as far as I am concerned. (…) we check everybody and for instance there are many more men than women who are arrested, that's crazy, there are also women who do wrong stuff. There're also women who drive without a license, there're also women who beat up their spouse. They're much less checked. Minorities will feel more persecuted whereas us… Eventually it's when we try to… but how many times have I been called a racist. Me, it gets on my nerves, something crazy, but me it gets on my nerves, but we are called racists, [voicing an imaginary dialogue]"you racists", "but Sir, do you know why we stopped you?", "yes for my mug", "well no Sir, your turn right, you forgot your turn signal"

The first theme of this quote is the concern about racism. When the respondent says "I can't stand it", he certainly means (unmade) accusations of racism. The respondent is outraged at being (implicitly) accused of racism, which ostensibly underlines his personal abhorrence of racism. Second, the lack of casualness in speaking about criminal activity among minorities is manifest in the broken structure of expression, hesitations, silences, and indignation, which we do not analyze as evidence of inner, hidden racism, but as evidence that such a topic is sensitive and controversial. Casual references to minorities as criminals undoubtedly sound racist in France. Third, the respondent is asked about racial profiling, and switches to the safer topic of gender imbalance in policing, implicitly saying that his understanding of "minorities" goes beyond "ethnic" minorities and extends to different type of minorities, such as women. This shows how French police officers may be reluctant to speak about ethnicity. This obviously does not mean that police "really" are colorblind, as research has consistently suggested (Body-Gendrot and Wihtol de [START_REF] Body-Gendrot | Police et discriminations raciales: le tabou français[END_REF][START_REF] Fassin | La force de l'ordre[END_REF]Open Society Institute, 2009;[START_REF] Pager | The Republican Ideal? Ethnic Minorities and the Criminal Justice System in Contemporary France[END_REF].

This defensiveness contrasts with Dutch and Italian officers. Many Dutch police officers make unequivocal associations between bad places, criminals and foreigners -or allochtonen. Allochtoon, often a short form of "non-western allochtoon", is the Dutch way to refer to ethnic minorities in the public space. It is a mostly uncontroversial word that is used by politicians of all persuasions and social scientists alike; only progressive social scientists object to its use (RMO, 2012;[START_REF] Vasta | From ethnic minorities to ethnic majority policy: Multiculturalism and the shift to assimilationism in the Netherlands[END_REF].

Dutch police officer 8: In this area, there are bad 'allochtonen'. I mean outside, not among the colleagues, but on the streets, the public… Not every 'allochtoon' is bad, but the most troubles on the street, when you talk about theft, robbery… most of the time, it's an 'allochtoon'. And that is very strange because there are 15 million Dutch people, most people are 'autochtoon', and if you go to jail, most criminals are 'allochtonen'.

Dutch respondents express clear-cut attitudes towards specific ethnic groups, especially Moroccans. Most respondents make a clear association between (presumed) Moroccans and crime, and our respondents sometimes referred to Moroccans as "kut Marokkanen" ("fucking Moroccans") or "kanker Marokkanen" ("this cancer that are Moroccans"). In practice, police officers often associate Moroccans with other groups. A much broader range of groups is potentially affected by the stereotypes described above: Turkish, Kurdish, Middle Eastern, and other North Africans. Police officers also stereotype Poles as criminal, but Moroccans are the focus of their concerns-they have replaced Surinamese, who used to be considered the dangerous minority by Dutch police officers in the 1970s [START_REF] Punch | Frontline Amsterdam: Policework in the Inner City[END_REF].

Question: Here everybody talks about Moroccans, why?

Dutch police officer 10: It's like a disease, I guess the whole community of that people, 90 per cent is wrong, 10 per cent is ok, people that want to work, the same who want to be the same as the Dutch people. When you watch the news on television or some programs, we call it 'Opsporing Verzocht' it's a program it's every Monday, Tuesday, you have the robberies and the criminals from the week before that and most are people from Morocco. And when you get an emergency call from dispatch, mostly it's people from Morocco.

A simple way to ascertain the sensitivity of a given topic is to listen to the small talk that fills space before or after more formal semi-structured interviews with sociologists-for instance, in the Netherlands, where one of us was casually asked by a police officer of Surinamese origin:

Dutch officer: Do you have specific types of people that cause trouble in France?

Researcher: What do you mean?

Dutch officer: Like, here we have the Moroccans; they cause a lot of problems.

Similarly, in Italy, ethnic categories are part of everyday conversations.

Italian security guard 1: Of course, knowing languages helps, I speak French, we have a new coworker who speaks English, it's very convenient, and at the supermarket, they have a guy who speaks German.

Italian head of security 1 [interrupting]: But they've never caught a German! [everybody laughs]

The comic twist of the joke lies in the understatement, "They've never caught a German"; Germans are not supposed to commit thefts, unlike, in the Italian context, Albanians, Romanians, or French-or English-speaking Africans. French respondents may privately share similar jokes, but they avoid doing so publicly. Italian respondents are straightforward in their designation of immigrants as problems and see no interactional problem in speaking about ethnicity.

Italian head of security 2: In Rome, we have a beautiful bright train station, but outside, in the two closest streets, it's neglected and deteriorated. You'll find all possible ethnic groups that will come and create troubles.

In Italy, the explicit designation of immigrants is not a controversial issue, whether in public space or during an interview. In the Milan train station, law-enforcement personnel speak of security problems by constantly referring to the presence of immigrants.

Italian police officer 1: For thefts, we've had another increase, because of Albanians and Romanians who have arrived. They don't deal drugs, I mean, some deal drugs, but then above all, they steal. There are also thefts with violence. Thefts that are not linked with drugs, they are mostly done by Slavs.

For law-enforcement personnel, ethnic categorization is conveyed through an association that Italian sociologists call immigrazione uguale criminalità, immigration = crime: "all the interviewees use national categories to describe the simplest crimes" (Quassoli 1999, p. 47).

Given nationalities become metonymies for given crimes. [START_REF] Pittau | Italia, paese di immigrazione : tra flussi regolari e irregolari[END_REF], there is not yet a second generation. Police officers therefore perceive them as foreign legal subjects and identify them as such. Italian and Dutch respondents speak openly about minorities. On the contrary, French discourse on ethnic groups is characterized by "colorblindness", which is the denial of the relevance of color, ethnicity or race in making sense of the world [START_REF] Bird | Racist Speech or Free Speech? A Comparison of the Law in France and the United States[END_REF][START_REF] Bleich | The Freedom to be Racist? How the United States and Europe Struggle to Preserve Freedom and Combat Racism[END_REF][START_REF] Brubaker | The return of assimilation? Changing perspectives on immigration and its sequels in France, Germany and the United States[END_REF]. Race is a sensitive topic and French police officers do not speak casually about it [START_REF] Lévy | Police, minorities and the French republican ideal[END_REF].

Italian

Anticipating accusations of discrimination (or not)

Casualness and awkwardness when speaking about ethnicity translate into different modalities of concern over the accusation of discrimination.

Italian respondents are virtually indifferent to a possible accusation of racism. In Italy, immigrants and minorities are often called "extracommunautarians", a word that means "immigrant not from the European Union". Asked about security problems in her mall, the general manager casually answers: "We have extracommunautarians but they stay quiet."

Assuming such an automatic relation between immigrants and trouble would be a deviance to French speech norms.

This contrasts with the Dutch case, where officers say they are accused of racism, and where there are rising concerns over ethnic profiling (van der Leun and van der Woude, 2011; Amnesty International, 2013). Most French respondents categorically rejected the idea that the ethnicity or the color of a person could influence their judgment in any way. French police officers insist that being objective and fair precisely means the avoidance of ethnic categories. This is in stark contrast with Italian and Dutch officers, who perceive the criminal world through these categories and do so openly and in a non-controversial manner. French police officers say they only act "according to the facts", that is, according to the nature and the seriousness of the offense committed. In this perspective, discrimination is nothing but a subjective, mistaken perception, made by citizens (abstract citizens) who are not able to understand the value of police work, or are prejudiced against the police.

Note the difference between the three types of discourse: Italian respondents are virtually indifferent to a potential accusation of racism, and speak freely about criminal activity of minorities; Dutch police officers also speak freely about criminal activity of minorities (in ways that would be labeled as racist in a French context), but they are not indifferent to a potential accusation of discrimination, which they discard by arguing about the overcriminality of minorities-a move that would be considered racist in France; French respondents are extremely concerned about avoiding an accusation of racism in the ways they speak about minorities, and they defend themselves against the potential accusation of discrimination by emphasizing the objectiveness and strict legality of their work and the ostensible belief that ethnic categories are irrelevant to their cognitive processes.

Theorizing minority crime: cultural (Italy, Netherlands) and structural explanations (France)

In this section, we look at the theories that police officers mobilize to make sense of the overrepresentation of minorities in criminal activity. For Dutch and Italian officers, culture explains minority crime, while French interviewees favor structural explanations.

Consider this Italian police officer, a white male in his forties, talking about Chinese and Moroccan immigrants. Chinese immigrants in Milan are not considered a criminal problem, whereas Moroccans are. For this officer, their respective cultural otherness best explains their different behavior. For this Italian police officer, it is in the culture of Chinese immigrants to solve criminal matters within the Chinese community without interference from the Italian judicial institutions, just as it is in the culture of Moroccan immigrants to slash their faces with knives and generally indulge in crime. In the Netherlands, Dutch police officers also emphasize cultural themes to explain the tensions they experience with Moroccans. Many police officers put forward the fact that Moroccans "don't want to adapt" to Dutch culture and society. [START_REF] Pakes | The politics of discontent: The emergence of a new criminal justice discourse in the Netherlands[END_REF][START_REF] Van Eijk | Exclusionary policies are not just about the 'neoliberal city': a critique of theories of urban revanchism and the case of Rotterdam[END_REF]Vasta, 2006 According to this police officer, crime is a matter of social problems rather than culture: migrants and ethnic minorities are over-represented in crime statistics because of the "unstoppable logic" of social problems: poverty, spatial relegation and the resulting discontent explain why immigrants and minorities offend more. Note how important it is for our French respondent to avoid political labeling: promoting a structural explanation for crime (which may sound progressive in the French political context), he takes pain to criticize "leftwing people" for blaming alleged discriminatory police practices. This quote is also a good example of the uneasiness with which French respondents talk about what they consider to be a sensitive topic: the many hesitations, unfinished sentences, and repetitions contrast with the straightforward casualness of their Dutch and Italian counterparts.

Italian police officer 2: [The

The invader, the enemy within and they-who-must-not-be-named

Our research design cannot allow for systematic inferences, but may be helpful to draw a typology that will need further testing. French, Italian and Dutch police officers differ in several ways in how they discuss minorities and what it reveals of their relationships. France is a country that is often opposed to the Anglophone world, and the United States in particular, for its "universalist" take on conceptions of citizenship and race [START_REF] Brubaker | The return of assimilation? Changing perspectives on immigration and its sequels in France, Germany and the United States[END_REF]. Our data reveal that France is very similar to the Anglophone world in its strict observance of speech norms governing race talk. French respondents seem to be affected by "political correctness": they are concerned about appearing racist, and they speak carefully to avoid that accusation. Minorities in France are "they-who-must-not-be-named": unspeakable but often on the mind. In the Netherlands, "Moroccans" actually are construed as an ethnic group, a threat to the cultural unity of the Kingdom, a problem that can be discussed openly and without infringing speech norms. Moroccans are the "enemy within" the Netherlands. In Italy, the concern for accusations of racism is less prevalent because minorities are not thought of (yet?) as ethnic groups, because they are still foreigners. Italian officers arrest people with a foreign passport, as opposed to nationals with a distinct ethnic identity. This is a fundamental difference with the Dutch case, with which the Italian one, otherwise, resembles. Immigrants are therefore more likely to be perceived as "invaders".

Conclusion

Our analysis raises a number of observations. The first one, regarding our first research question, is that there are important variations in speech norms. French officers respect strict speech norms, while Dutch and Italian officers use language that would seem appalling in the Anglophone world. In effect, the discursive construction of the "symbolic assailant", of the bad minority, is country-specific. "Arabs" (Algerians, Moroccans and Tunisians), West Africans and Roma people in France; Romanians, Albanians, Moroccans and Roma people in Italy; Moroccans and Poles in the Netherlands: there is an element of diversity in this list where skin color ("race" in the United States) is not the mother of all "racial" categorization. The distinctions we have made in our typology add to the scholarship that warns against the uncritical projections of American conceptions of race onto other realities [START_REF] Bourdieu | On the cunning of imperialist reason[END_REF].

The second observation is that Dutch and Italians are racist by French standards, but they are not racist by Dutch and Italian standards. The national definition of what is racist varies more than many may expect. In the Anglophone world, strict non-racist speech norms regarding race are expected of any somewhat-developed country. Openly racist discourse (by French or Anglophone standards) may be perceived as evidence of racial backwardness. But such reasoning only applies by using racism as a category of analysis, an objective standard by which any country can be judged, with French and Anglophone activists arguing over the respective merits of colorblind and race-conscious conceptions of non-racism. Seen from a Dutch perspective, or an Italian perspective, how Dutch and Italians speak about minorities would not be perceived as "racist" in polite society. Of course, there are many academics and activists, both in the Netherlands and Italy, who are working to change speech norms, partly under the influence of Anglophone conceptions of what is racist discourse and what is not (for instance, Palidda, 2011). How these norms circulate, through which venues, and how they are reinterpreted locally, should be studied more systematically.

A consequence of that-our third observation-is to ask why different countries have different conceptions of what is racist and what is not. Our research design is unable to answer that question. But assuming that the speech patterns we have documented are not local artifacts (an assumption that is consistent with the literature), we observe that there is no simple structural explanation that fits. France and Italy are fairly different when it comes to the amount and timing of immigration, but France and the Netherlands both have similar numbers of immigrants, who arrived within similar time frames; they both were colonial empires; the three countries collaborated with Nazi Germany to perpetrate the Holocaust. The only factors that seem explanatory are the idiosyncrasies of national public spheres and the development of national models of citizenship [START_REF] Brubaker | Citizenship and Nationhood in France and Germany[END_REF].

Finally, and this is our fourth point, regarding our second research question: it is widely assumed within the social sciences that discourse matters, but the variations in discourse we observe are mostly inconsequential when it comes to practice. Strict non-racist speech norms do not translate into non-racist policies. Chronic rioting in France, almost systematically triggered by an event of police misconduct, suggests that French speech norms do not cause minority-friendly policies-just as British or American speech norms do little to prevent racialized outcomes in policing and sentencing. Strict non-racist speech norms may be a worthy endeavor, but they are a long way from changing actual policies that systematically impair the life chances of minorities.

  Dutch officer 3: There are only one or two minorities that don't respect the police. For example, Moroccans, they don't like the police at all, but the police don't like Moroccans too, so… (…) It comes from their… you know, the first Dutch word they learn is "oh you are a racist" because you are a white girl, you get a fine for driving through a red light, for example, I write a fine to you, you say, "ok, I don't like it, but thank you" and I say "have a nice day", but I write exactly the same fine to a Moroccan guy or girl, they say "hey, this is because I'm from Morocco, [mocking an Arab accent] blablabla", exactly the same.In this quote, accusations are immediately dismissed in a contemptuous manner ("the first Dutch word they learn is 'oh you are a racist'"). According to Dutch officers, it is widely known, and non-controversial to say it, that Moroccans commit more crime than Dutch autochtonen. Dutch police officers do not see themselves as racist and profess that they treat all offenses equally, even when they mock an Arab accent, which would be shockingly racist in France.Consider the French defense against the accusation of discrimination.

French officer 15: …on certain types of public that always feel victimized, that have the impression of being always checked. But once again, they play on it. If they are checked, it's because there is something wrong. They don't wear their seatbelt, they have committed an offence, they drive too fast, so there is always a reason for the check, it's not for fun. We are checking because there is something fishy, in a way.

Minorities (unnamed as such) "feel victimized", as opposed to being the victim of discrimination. But, in the officers' logic, there cannot be discrimination, since officers are colorblind. The legitimacy of arrests is taken for granted: if the police arrest someone, there must be a legitimate reason, for French police officers are proud enforcers of the law.

French officer 9: what do you mean, discrimination?! What does that mean?! The offender has no color (…) Oh yes, "you only stop blacks and Arabs" no, no. (…) For me, the job how I see it, it is 'crime has no color'. It is my motto. I can deal with an Arab, a black or a white, or a green, a Martian, for me, it's the same.

  Chinese] have their own neighborhoods, their own laws. If they steal from each other, they won't go to the police to press charges. They settle it down among themselves. They have a different language, a different culture. None of them would collaborate with us, they are incredible and they are all the same.

(…)

Chinese people are incredible. You don't hear anything from them because there isn't a particular crime committed by the Chinese. (…) For Milanese people, Chinese people are not a threat, whereas Moroccans are, it's in their culture, they slash up their faces with their knives, you'll always see that. These are different cultures. Europeans have houses which they always more or less keep neat. The Moroccan guy, he always lives in his dirt, he has another relation to cleanliness, and I am not saying that out of racism! But they are dirty, they never wash their dishes, they let it pile up. (Police officer, Italian train station)

  Dutch officer 3: I think that in France, you have the same problem with Algerian people. Why do always Moroccans or Algerians have a problem? I think, they don't want to integrate in the new country. If I go to Morocco, on holiday for example, I have to listen and I have to adapt myself to their culture, I have to wear long trousers, I cannot look at their women, I was in Iraq so I know how it works, never show your left foot to a Muslim, don't wave with your left hand because it's not clean, you know, that is the basic rules in Muslim culture. So when I go to a Muslim country, I try to adapt myself to the Koran, maybe not to the Koran but to the Muslims as much as possible.This type of argument is widespread in Dutch public debate, but only since the 2000s, following the publication of a newspaper article called "The Multicultural Tragedy" by sociologist Paul Scheffer, and the murders of populist politician Pim Fortuyn in 2002 and director Theo van Gogh in 2004

	So
	when a Muslim comes to our country, he has to know how it works in our country
	because for example we can look at other women, we can sit like this [legs wide open],
	you can see my foot sole, when I see someone I say "hey" with my left hand, it's all this
	kind of little things are little differences but when a guy from Morocco comes to my
	country and expects from me that I adapt to him, I think that is wrong.

  ). Right-wing politicians often criticize Moroccans for not showing enough good will in assimilating to Dutch society, and publicly doubt that Moroccans can assimilate at all, because of their culture and adherence to Islam, which is considered by Dutch populist parties as a generally backwards religion whose core values are antithetical to the Dutch liberal tradition of tolerance. In the same way, Dutch respondents also refer to the 2005 French riots, which they interpret as the confirmation of a cultural problem with North Africans. It seems to me that it's an unstoppable logic. When we hear left wing people, they say there is discrimination but it's not true at all. Society makes what it's going to be of these people. That's it, so it will be immigration from Africa, from North Africa, that's all. We will find these people. Now there are many Eastern countries because it's them who come here. But it's not especially… It's how it goes, that's it. It's the unhappy people, who steal, who… That's all. And unhappy people, who is it now: it's the immigrants. I'm not especially, nothing, but it's the unstoppable logic, like it must be everywhere, like in the US, they say minorities, the Latinos, yes because the Latinos, maybe they work in a factory, on the assembly line, they are penniless, they can't get decent housing, so at some point to escape all that, there is one of them that is going to, maybe sell some drugs, there is no… It's society that wants it.

	French respondents give different arguments to explain the overrepresentation of ethnic
	groups in crime statistics. Many French police officers favor what sociologists would call a
	structural explanation.
	French officer 6: But it's true that… and I'm really quite objective, unfortunately… I
	mean… people with an immigrant background, they are in social housing, they are the
	ones that have less money, and they are the most disadvantaged, so necessarily it's an
	unstoppable logic. There is no, there is not… It's inevitable, crime is going to come
	from where, it's coming from these people. Without being… I'm not especially left wing
	or right wing, I'm nothing at all.

Table 1

 1

	typifies our results and provides the number of respondents for each country who fit the
	speech norms pattern that we have documented (n/a's refer to interviews in which our main
	concern was not discussed).
	Item	France	Netherlands	Italy
	Explicit designation of	No	Yes	Yes
	minorities

Table 1 :

 1 Summary of results

Acknowledgments

We are grateful for the useful feedback from Laura Boschetti, Francesco Ragazzi, Guillaume Roux and Clément Théry. This paper has been financially supported by the SPACECONTROL project (ANR no ANR-10-ESVS-001-01), at Maison européenne des sciences de l'homme et de la société (MESHS -USR 3158).