import structure FD from "x-alice:/lib/gecode/FD"
import structure Modeling from "x-alice:/lib/gecode/Modeling"
import structure Explorer from "x-alice:/lib/tools/Explorer"
import structure Space from "x-alice:/lib/gecode/Space"

open Modeling

fun mapColoring space =
 let
    val nbColors = FD.range(space,(1,10))
    val countries as #[au,ge,ne,sw,be,ita,po,fr,lu,sp] =
    	    FD.rangeVec(space,10,(1,10))
    (* borderTo gets a country and its neighbours and
          ensures they do not have the same color *) 
    fun borderTo(space,c,nvec)=
    		Vector.app(fn x => FD.rel(space,c,FD.NQ,x))nvec
 in
    FD.branch(space,#[nbColors],FD.B_NONE,FD.B_MIN);
    Vector.app(fn x => FD.rel(space,x,FD.LQ,nbColors))countries;
    borderTo(space,au,#[ita,sw,ge]);
    borderTo(space,be,#[fr,ne,ge,lu]);
    borderTo(space,fr,#[sp,lu,ita]);
    borderTo(space,ge,#[au,fr,lu,ne]);
    borderTo(space,sp,#[po]);
    borderTo(space,sw,#[ita,fr,ge,au]);
    FD.branch(space,countries,FD.B_SIZE_MIN,FD.B_MIN);
    { netherlands = ne, belgium = be, france = fr, spain = sp,
      portugal = po, germany = ge, luxemburg = lu, italy = ita,
      switzerland = sw, austria = au,nbColors}
 end
    
(* Explorer.exploreOne(mapColoring) *);