% This is a proof that socrates is mortal, using prover9. % Usage: % prover9 -f sqrt2.in > sqrt2.out % Use prolog-style names (initial uppercase is a variable): set(prolog_style_variables). formulas(assumptions). man(X) -> mortal(X). % If X is a man, then X is mortal (all men are mortal). man(socrates). % Socrates is a man. end_of_list. formulas(goals). mortal(socrates). % Therefore, Socrates is mortal. end_of_list.