1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | $ $ N-queens in Essence'. $ $ Using the 3 alldifferent approach with matrix comprehensions. $ $ Model created by Hakan Kjellerstrand, hakank@gmail.com $ See also my Essence'/Tailor page: http://www.hakank.org/savile_row/ $ $ Licenced under CC-BY-4.0 : http://creativecommons.org/licenses/by/4.0/ $ language ESSENCE' 1.0 $ given n : int(1..) letting n be 8 letting dom be domain int (1..n) find x: matrix indexed by [ dom ] of dom $ branching on x $ heuristic srf such that allDiff (x), allDiff ([x[i]+i | i : dom]), allDiff ([x[i]-i | i : dom]) |