Dear Forum, Dear Ms. Brillmanns, On Nov 18, 2011, at 11/18/11 2:09, Lisette Brillemans wrote: > > pair:=function(x,y); return[x,y]; end; > > not ListX(Combinations(a,2),Combinations(a,2),\=,Pair) > > which leads to: Variable: 'Pair' must have a value.
GAP is case sensitive, so clearly that won't work. > So, \< isn't entirely "for nothing" because now "\<\>" doesn't work > either. And using "not" isn't a solution for that. > > Or am I seeing this wrongly? Yes, you are. There is no magic with prepending \ to comparison operators, but GAP just has two comparison operations: strictly smaller and equal. All other comparisons can be built from these two with logic operations. The identifier for the smaller operation is \< (since it looks rather natural; the \ is needed to make it a proper identifier versus the < binary operator). The identifier for equal is \=. As so often, this is explained in the manual (look in the index under ``comparison''): http://www.gap-system.org/Manuals/doc/htm/ref/CHAP030.htm#SSEC011.1 Other functions are not defined, though if you needed an (a>b) function, for example you could simply define. LargerComparison:=function(a,b) return a>b;end; or you could even call it \> Regards, Alexander Hulpke _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
