language ESSENCE' 1.b.a
$ Futoshiki puzzle solver, by Andras Salamon
$ see http://en.wikipedia.org/wiki/Futoshiki
$ the instance is specified in the parameter file

letting   SIZE   be 5
letting   NUMQD  be domain int( 0..lastdx )
letting   RANGE  be domain int( 1..SIZE )
letting   VALUES be domain int( 0..SIZE )
$ the numeric values specified in the puzzle
given     values : matrix indexed by [RANGE,RANGE] of VALUES
$ index of last lt entry
given     lastdx : int( 1..((2*SIZE*(SIZE-1)-1)) )
$ list of < relations in the problem
given     lt     : matrix indexed by [NUMQD, int(0..3)] of RANGE

find      field  : matrix indexed by [RANGE, RANGE] of RANGE

such that
$ all rows have to be different
    forall row : RANGE .
	alldifferent(field[row,..]),

$ all columns have to be different
    forall col : RANGE .
	alldifferent(field[..,col]),	 

$ all < constraints are satisfied
    forall i : NUMQD .
	( field[ lt[i,0], lt[i,1] ] < field[ lt[i,2], lt[i,3] ] ),

$ set initial values
    forall row,col : RANGE . 
	( values[row,col] > 0) =>
	    (field[row,col] = values[row,col] )