change (X,Y) notation to only Y (the x is unnecessary)

[ThierryDeruyttere]

No description provided.

[arminnh]

Sudoku ECLiPSe solver with the second viewpoint:
change
NumbersPositions[1..N, 1..N, 1..2] :: 1..N
to
NumbersPositions[1..N, 1..N] :: 1..N
and update all uses of the NumbersPositions array.
if we have enough time to do this before the deadline