[GAP Forum] AddRule in KnuthBendixRewritingSystem

[Carl-Fredrik Nyberg Brodda (MTH - Postgraduate Researcher)]

Hi all,

I am having issues with the AddRule() function for KnuthBendixRewritingSystems, in that I cannot get it to work at all. I am using GAP 4.11.0

Here is a minimal non-working example:

F := FreeMonoid(1); k := KnuthBendixRewritingSystem(F/[]); AddRule(k, [[1,1], [1]]);

This gives the error message :
Error, no method found! For debugging hints type ?Recovery from NoMethodFound
Error, no 1st choice method found for `AddRule' on 2 arguments at /usr/local/gap-4.11.0/lib/methsel2.g:249 called from
<function "HANDLE_METHOD_NOT_FOUND">( <arguments> )

On the other hand, the command

F := FreeMonoid(1); k := KnuthBendixRewritingSystem(F/[]); AddRuleReduced(k, [[1,1], [1]]);

works perfectly well, and adds the rule F.1*F.1 -> F.1 to the system, even though it should take exactly the same arguments as AddRule. The command "AddRuleReduced", however, imposes an ordering on the added rule, which I do not want, so I cannot use this.

What is going wrong here?

Best,
Carl-Fredrik Nyberg Brodda