Dear Sven, Most probably the orb package is what you need: http://www.gap-system.org/Packages/orb.html
best, attila On Fri, May 17, 2013 at 6:53 PM, Sven Reichard <sven.reich...@tu-dresden.de> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Dear Forum, > > I have the following data: > - - A permutation group G; > - - a set of objects obj; > - - an action function. > > I would like to get the following: > - - The union D of the orbits of obj under G (not necessarily sorted); > - - the action H of G on D; > - - orbit representatives. > > What I do is the following: > > orbits := Orbits(G, obj, action); > representatives := List(orbits, Representative); > D := Union(orbits); # sorted to accelerate the next step > H := Action(G, D, action); > > This works well when action is a standard action such as OnSetsSets. > However, for custom actions this can be very slow, suggesting that > different algorithms are used. (In some of my examples, D has a > million elements.) > > Is there a way in GAP4 to accelerate this process, for example by > providing hash functions? In GAP3 there existed a solution in the > contributed file coco.grp by Theißen based on work by Faradzev et al. > The question is whether there is a better way than porting that file > to GAP4. > > Regards, > Sven Reichard. > > - -- > > Institut für Algebra > TU Dresden > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.5 (GNU/Linux) > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQEVAwUBUZXwI2FjB3Gki4XVAQJrDgf+IdzNftD5zutKuXm/7vOWQhSOe6ZdeJ8p > N+FWYHgXYuHfHPrXquv/iUzVKRaADu01+enk/T9sYIr6oEorcAO5GS0uh/5yhBSq > IqL5jsvkyCbrW3jN8sjGUZanGw5z81cjx5VoigYuaON8VMB8qGMQ6w20B+0XdTss > 29YZJZz1r2JMNB/Lfx7iiqHCRalfK1+qnnvimro404H2jc+sjvGH83nh6z3uZLy4 > eaDBOaJgI2Uz8Nz3SL2KBEzhQ02Ipem3jEC37izS9Or20zotcog/G3v0uLsy10/G > y7mcQ0lfhxH4PwQ1OpTbvFD4WHNQ1riMTmG5qtZgP9d7uymKBssmMA== > =JAOJ > -----END PGP SIGNATURE----- > > _______________________________________________ > Forum mailing list > Forum@mail.gap-system.org > http://mail.gap-system.org/mailman/listinfo/forum _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
