Prolog doesn't do that automatically, but you can write the same thing in Prolog too: xkcd_ugly(A, B, C, D) :- P = 711, Q = 711000000,

Prolog doesn't do that automatically, but you can write the same thing in Prolog too: xkcd_ugly(A, B, C, D) :- P = 711, Q = 711000000, Max_A is 1 + P // 4, between(1, Max_A, A), Q mod A =:= 0, Max_B is 1 + (P - A) // 3, between(A, Max_B, B), Q mod (A * B) =:= 0, Max_C is 1 + (P - A - B) // 2, between(B, Max_C, C), D is P - A - B - C, A * B * C * D =:= Q. In SWI-Prolog, I get the following timings: ?- time(xkcd_ugly(A, B, C, D)). % 383,992 inferences, 0.056 CPU in 0.056 seconds (100% CPU, 6825328 Lips) A = 120, B = 125, C = 150, D = 316 ; % 3,274 inferences, 0.003 CPU in 0.003 seconds (100% CPU, 1229464 Lips) false. That is to say, it found the first solution in 0.056 seconds CPU time, then took an additional 0.003 seconds to prove that there are no further solutions. (This is the minimum of a handful of runs, there is quite a bit of variation.) Quick and very dirty benchmarks on the same machine run your Python code in about 0.02 seconds. The CLP(FD) code above takes about 0.1 seconds but it's a lot clearer.