Dear GAP-Forum,
Rudolf Muradian wrote:
gap> d2 := DihedralGroup(2); Size(d2); Group( (1,2), (3,4) ) 4 gap> d4 := DihedralGroup(4); Size(d4); Group( (1,2) ) 2 Is here a bug ?
Yes. The special treatment for degrees 2 and 4 went wrong. To fix it,
replace the function 'DihedralPermGroup' in the file ~gap/grp/permgrp.grp
by the following code:
############################################################################# ## #F DihedralPermGroup( <n> ) . . . . . . . . . . dihedral permutation group ## DihedralPermGroup := function ( n ) local D, g, h; if n = 2 then D := Group((1,2)); elif n = 4 then g := (1,2); h := (3,4); D := Group( g, h ); else g := PermList( Concatenation( [2..n/2], [1] ) ); h := PermList( Concatenation( [1], Reversed( [2..n/2] ) ) ); D := Group( g, h ); fi; return D; end;
Best regards,
Alexander Hulpke
PS.: This should also answer your two other mails. A.H.