1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | language Essence 1.3 $ prob024.essence: Langford's Number Problem $ Problem details available at http://www.csplib.org/Problems/prob024 given k : int (2..5) given n : int (1..30) letting seqLength be k * n letting seqIndex be domain int (1..seqLength) find seq : function ( total , surjective ) seqIndex --> int (1..n) such that forAll i,j : seqIndex , i < j . seq(i) = seq(j) -> seq(i) = j - i - 1 |