Hi, I have done a bit of homework on the automorphism group computation of matroid and efficient minor testing.
For minor testing,what Petr Helineny did is to compute some magic numbers (Numbers that are invariant on operations like scaling and permuting lines ) of matrices and compare these numbers for faster rejections.The numbers he had used are *zero 2X2 sub determinants*,*zero patterns of lines, numbers based on small flats* I think the way to go is inserting these checks in the *has_minor()* method we already have. Coming to the automorphism group computation, i'm confused as i see two approaches.One being, constructing the graph as you suggested and call the *automorphism_group(partition=[X,Y]).*Since the graph is going to be exponential in the size of groundset, we need to implement it in a clever way. The other approach is to implement the refinement_matroids.pyx with the three functions ( all_chidren_equivalent,refine_and_return_invariant,compare_structures). I've seen this approach discussed last year in the group. Please comment if i'm going in the right direction. Thanks Rajesh Veeranki. On Wed, Feb 26, 2014 at 6:53 PM, Nathann Cohen <[email protected]>wrote: > Hellooooooooooo !!! > > > For the automorphism group, the way to go is to construct an appropriate > graph (e.g. a bipartite one with the elements on one side, the non bases on > the other, and an edge if the element is contained in the non basis), and > compute the automorphism on that graph that preserves the sides of the > bipartition. > > Some thing that ? > > sage: Hypergraph.automorphism_group?? > > Nathann > > -- > You received this message because you are subscribed to the Google Groups > "sage-gsoc" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sage-gsoc. > For more options, visit https://groups.google.com/groups/opt_out. > -- *Rajesh Veeranki** | Senior Undergraduate | **C.S.E** | **IIT Bombay* -- You received this message because you are subscribed to the Google Groups "sage-gsoc" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-gsoc. For more options, visit https://groups.google.com/groups/opt_out.
