[PPL-devel] [Xsb-development] Arithmetic evaluation bug in the CVS HEAD version of XSB

[David Warren]

Bart Demoen writes:
 > What I later pasted in my mail was some sort of abbreviation of some
 > of the queries. I didn't even notice it was showing some different
 > weird behaviour. I now realize that toplevel queries of </2 can behave
 > differently from compiled goals. The problem with compiled </2 is that
 > XSB compiles X < Y to X-Y < 0 (or something like that - when there is
 > (undetected ?) overflow in the -/2, things go wrong.

Ah yes.  Thanks for that insight.  Hmmm, looks like we should first
detect overflow, and then figure out how to change the compiler to not 
use difference to compile comparisons.

-David