Hi Nathann, Nicolas, and Robert! On 26 Jan., 11:38, "Nicolas M. Thiery" <nicolas.thi...@u-psud.fr> wrote: > Actually, I once needed it so badly, that I hacked a quick > workaround. And it inadvertently went into Sage as part of another > patch (oops, shame on me and on the reviewer!). So now you can do: > > sage: G = digraphs.DeBruijn(5,0) > sage: hash(G) > Traceback (most recent call last): > ... > TypeError: graphs are mutable, and thus not hashable > sage: G._immutable = True
Ouch. Anyway. My aim is to implement finite-dimensional quotients of path algebras as part of a project to compute modular cohomology rings of basic algebras. A path algebra should be a unique parent, associated with a base ring and a labeled multi-digraph with loops. But since the graphs themselves are not hashable, I guess one has to use some unique description for them. I guess the ordered tuple of its edges (an edge being a triple of start point, end point, and label) is an appropriate key, usable in UniqueFactory. Best regards, Simon -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
