Dear friends;I would be very grateful if you advice/help m to handle a situation related to GAP: If N is a subgroup of H, H is subgroup of G, and N is normal in G; then H/N is subgroup of G/N. The problem is that GAP does not recognize it so. I have constructed the following code to check quotient closeness for some property, The code is: IsQClosedNSPSubgroups:=function(g) local pn,nsp,i,j,m;
if IsAbelian(g) then return true; fi; pn:=ProperNormalSubgroups(g); if Size(NormalSubgroups(g))=Size(Subgroups(g)) thenreturn true; fi; nsp:=NSPSubgroups(g); for i in [1..Size(pn)] do m:=Filtered(nsp,x->IsSubgroup(x,pn[i])); for j in [1..Size(m)] do if notIsNearlySPermutable(FactorGroup(g,pn[i]),FactorGroup(m[j],pn[i])) then return false; fi; od; od; return true; end; THE ERROR MESSAGE IS: Error, no method found! For debugging hints type ?Recovery from NoMethodFoundError, no 1st choice method found for `IsNormalOp' on 2 arguments called fromoper( super, sub ) at /proc/cygdrive/C/gap4r7/lib/domain.gd:439 called fromIsNormal( g, h ) at *stdin*:427 called fromIsNearlySPermutable( FactorGroup( g, pn[i] ), FactorGroup( m[j], pn[i] ) ) at *stdin*:685 called from<function "IsQClosedNSPSubgroups">( <arguments> ) called from read-eval loop at line 691 of *stdin*you can 'quit;' to quit to outer loop, oryou can 'return;' to continue Thank you for your advice. _______________________________________________ Forum mailing list Forum@gap-system.org https://mail.gap-system.org/mailman/listinfo/forum
