From: SourceForge.net <noreply@so...>  20051008 20:52:24

Bugs item #1318843, was opened at 20051008 14:52 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core Group: None Status: Open Resolution: None Priority: 5 Submitted By: Robert Dodier (robert_dodier) Assigned to: Nobody/Anonymous (nobody) Summary: assume failure to deduce, and consequent infinite looping Initial Comment: assume (a > 0, b > 0, c > 0, d > 0); assume (c*s + d < 0); assume (equal (c*r + d, 0)); At this point, r = d/c and s < d/c, so s < r. However, integrate ((a*x+b)/(c*x+d), x, r, s); => Is s  r positive, negative, or zero? response: n; => a solution response: p; or z; => somebody calls ASKSIGN1 over and over 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) ((MTIMES SIMP RATSIMP) 1 $D) ((MTIMES SIMP RATSIMP) 1 $C $R))) <1 (ASKSIGN1 $ZERO) 1> (ASKSIGN1 ((MPLUS SIMP) $D ((MTIMES SIMP RATSIMP) $C $R))) <1 (ASKSIGN1 $ZERO) etc etc indefinitely. There are at least 2 problems here. (1) ASKSIGN failed to determine that s < r and therefore there is no need for asking about it. (2) If the response implies something inconsistent with the facts assumed thus far, something (maybe ASKSIGN) goes nuts. I'm inclined to think (2) is more serious. Whatever the limitations of the assume mechanism to derive stuff from facts, it shouldn't freak out under any circumstances. Problem verified in 5.9.0 on Allegro CL 6.2, and 5.9.1.9rc4 on GCL 2.6.7.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1318843&group_id=4933 