Hi there, I believe the following behavior of the CVS version of YAP witnesses a bug (or, quite possible, a misunderstanding on my part): $ yap [ Restoring file /usr/local/lib/Yap/startup ] [ YAP version Yap-4.3.23 ] ?- current_prolog_flag(bounded,X). X = false ? ?- X is 333333333333333, integer(X). no ?- X is 33333333, integer(X). X = 33333333 ? ?- X is 333333333333333, float(X). no ?- X is 333333333333333, number_chars(X,L). X = 333333333333333, L = [51,51,51,51,51,51,51,51,51,51,51,51,51,51,51] ? In words, the Prolog engine first declares it is employing unbounded integers, then it silently converts an integer numeral to... to what? Is this a bug? Am I missing something? All the best Roberto -- Prof. Roberto Bagnara Computer Science Group Department of Mathematics, University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it