Der Forum, > On Sep 3, 2015, at 7:44 AM, Benjamin Sambale <benjamin.samb...@gmail.com> > wrote: > > the command SchurCoverOfSymmetricGroup can be used to define the two double > covers of a symmetric group. According to the manual: > > "+1 gives a group where the preimage of an adjacent transposition (i,i+1) has > order 4" > > I thought that the convention is just the other way around: in the "+" type > cover the transpositions lift to involutions.
Looking through the literature going back to Schur’s original papers it seems that what is considered the ``canonical’’ or ``+1’’ cover is not consistent. GAP’s convention thus represents a necessary choice made by the code authors which I find hard to criticise. We will add a warning line to the manual to alert users to this difference of conventions, thus hopefully avoiding further confusion. Best wishes, Alexander Hulpke -- Colorado State University, Department of Mathematics, Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA email: hul...@math.colostate.edu, Phone: ++1-970-4914288 http://www.math.colostate.edu/~hulpke _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
