a :- b. a :- \+ a. b :- a. % > swipl cyclic.pl % ERROR: /home/fc/sci/projetos/plp/code/asp/cyclic.pl:2: % ERROR: Stack limit (1.0Gb) exceeded % ERROR: Stack sizes: local: 1.0Gb, global: 27Kb, trail: 1Kb % ERROR: Stack depth: 7,455,777, last-call: 0%, Choice points: 7,455,758 % ERROR: Probable infinite recursion (cycle): % ERROR: [7,455,777] user:p % ERROR: [7,455,776] user:p % Warning: /home/fc/sci/projetos/plp/code/asp/cyclic.pl:2: % Warning: Goal (directive) failed: user:p %