[GAP Forum] A problem with Lists

[Steve Linton]

Dear GAP Forum,

Hubai Tamas asked:

>A segmentation fault occurs upon evaluating the following expression:
>gap> [~]=[~];
>
>There are also some variations for this, such as [~]=[[~]], but the 
>originating problem is probably the same.
>
>I have checked this issue with gap 4.4.4 (and also with gap 3) on both 
>Windows and Linux systems. It does not seem to be os-specific.

This is a known problem, where the elementwise comparison of lists causes an
infinite recursion. It would be possible to add code to deal with it, but it
would slow down all list comparisons slightly, and it is, in any event, far
from clear what the right answer actually is.

We will improve the documentation of this issue for the next release.

	Steve Linton

-- 
Steve Linton	School of Computer Science  &
      Centre for Interdisciplinary Research in Computational Algebra
	     University of St Andrews 	 Tel   +44 (1334) 463269
http://www.dcs.st-and.ac.uk/~sal	 Fax   +44 (1334) 463278