PS: On 2013-07-12, Simon King <simon.k...@uni-jena.de> wrote: > Hi Volker, > > On 2013-07-12, Volker Braun <vbraun.n...@gmail.com> wrote: >> How about >> >> 3. Disallow invalid paths as paths and path algebra elements. > > No way. Otherwise, the algebra would only have a partially defined > multiplication, which makes it not an algebra.
Put differently: If a and b are elements of the free small category associated with a quiver Q, and A is a path algebra over Q, then we must have A(a*b) == A(a)*A(b) But if a and b can't be composed, then currently A(a)*A(b) is zero, but A(a*b) is not. Cheers, Simon -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/groups/opt_out.
