[GAP Forum] Rewriting steps in fp groups

Gábor Nagy nagyg at math.u-szeged.hu
Wed Jun 20 08:12:17 BST 2007


Dear Forum,

I have a relatively small fp group G of order 3840 given by 2 generators 
and 6 relators. According to GAP, a given word w of G is equal to 
One(G). However, for a publication, I want to show w=1 in a "human 
readable" format.

Therefore I need the steps how GAP rewrites w to 1.

My question is if it is possible to output the steps of the rewriting 
process in GAP?

Thanks in advance, bye,

Gabor Nagy

==============================

gap> f:=FreeGroup("c","d");
<free group on the generators [ c, d ]>
gap> rels:=[f.1^2,f.2^8,(f.1*f.2)^5,Comm(f.1,f.2)^3,Comm(f.1^2,f.2)^2,
 >       Comm(f.2^4,Comm(f.2^2,Comm(f.2,f.1)))];
[ c^2, d^8, c*d*c*d*c*d*c*d*c*d, 
c^-1*d^-1*c*d*c^-1*d^-1*c*d*c^-1*d^-1*c*d, 
c^-2*d^-1*c^2*d*c^-2*d^-1*c^2*d, d^-4*c^-1*d^-1*c*d^-2*c^-1*d*c*d^
4*c^-1*d^-1*c*d^2*c^-1*d*c ]
gap> g:=f/rels;
<fp group on the generators [ c, d ]>
gap> Size(g);
3840
gap>
gap>
gap>
gap>
gap> w:=Product(Orbit(g,g.2^4));
d^4*c^-1*d^4*c*d^-1*c^-1*d^4*c*d*c^-1*d^-1*c^-1*d^4*c*d*c*d^-1*c^-1*d^
-1*c^-1*d^4*c*d*c*d*c^-1*d^-1*c^-1*d^-1*c^-1*d^4*c*d*c*d*c
gap> w=One(g);
true



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