added another prolog example

documents/Programmierparadigmen/scripts/prolog/01-two-bases.prolog

@@ -0,0 +1,15 @@
+#!/usr/bin/swipl -q -t main -f
+% Find three digits X, Y and Z such that
+% XYZ in base10 is equal to ZYX in base9
+
+is_solution(X, Y, Z) :- between(0,9,X),
+                        between(0,9,Y),
+                        between(0,9,Z),
+                        Base10 is (100*X + 10*Y + Z),
+                        Base9 is (9*9*Z+9*Y+X),
+                        Base10 = Base9.
+
+main :-
+    is_solution(X, Y, Z),
+    format("solution: ~w ~w ~w\n", [X,Y,Z]),
+    false. % make sure that all solutions get printed