(I hope you don't mind that I forward to aldor-combinat. But I'll describe an idea below, that I want to archive there...)
"Mike Hansen" <[EMAIL PROTECTED]> writes: > > This looks deceptively simple. Are you sure it's correct? > > This is just for ordinary species. what is an "ordinary species"? You mean, it's only for the structures, not the isotypes? > The only differences between it and your code for isomorphism types is that I > use the getattr stuff to avoid writing the same algorithm twice and that I > use CartesianProduct which I had already written elsewhere in Sage. Are you saying that you took the algorithm from trunk? If so, then it's incorrect. Unfortunately, I don't have an example right now, but I think there should be an appropriate test in our testsuite (which is failing in trunk, of course). I should make it explicit, I admit. I'd be *very* interested in a *good* design for isotypes that works with representatives. I think one way to do it would be to separate the structure from it's labels. More precisely, a structure could be represented as an "isotype" together with a bijection that gives the structure the appropriate labelling. Of course, this representation is not unique, i.e. we can represent, say, the binary tree (1,(2,3)) as isotype = (1,(2,3)) - pi = id or as isotype = (2,(1,3)) - pi = 2->1, 1->2, 3->3 But maybe, this wouldn't matter for the generation of compositions as long as the representation is deterministic. Martin ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Aldor-combinat-devel mailing list Aldor-combinat-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aldor-combinat-devel
