Solution Search #1: Permutations of List of Unique Values Use a list containing the numbers 0 through N-1 as a list of queen positions. Indexes will represent columns and the value in the list at that index will represent the row position for the queen in that column. For N=8, you can use permutation([0,1,2,3,4,5,6,7],X). We know from the discussion above that there are about 40 thousand possible values of X. Prolog will try each of them via backtracking. For a general value of N, you will first need to define a predicate that constructs a list of values from 0 through N-1, then take the permutation of that list. Define a predicate nc/3 that confirms that a specific column pair have no conflicts for a specific list of positions: nc(L, A, B). L: list of queen positions A,B: indexes into list L, assume 0