Dear Ralf, I'm answering to the archive, I hope you don't mind.
You asked, whether I believe that ranking and unranking makes sense only for linear species. I'm not sure yet. A priori, the theory of linear species lends itself to ranking and unranking, since within this theory we assume an order on the input set of the functor. The trouble stems from the fact that for this idea to work we need to be able to construct two linear species from each usual species: one for the structures (i.e., labelled objects) and one for the isomorphism types (i.e., unlabelled objects). However, I'm not sure whether this can be done in a generic fashion. The labelled objects are obtained easily, this is Remark 5 in Section 5.1. of BLL. However, I don't see a way to obtain the unlabelled objects yet. I should probably look into Molinero's thesis to see some examples, maybe that would help. The reason I'd like to have some examples is that in the holonomic case (i.e., only Plus and Times and CharacteristicSpecies), there is no difference between labelled and unlabelled. Things become complicated only with things like SetSpecies or Compose in the unlabelled case. Martin ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Aldor-combinat-devel mailing list Aldor-combinat-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aldor-combinat-devel
