Hi all, I had a conversation with John Palmieri and Simon King on sage-support about cohomology and Steenrod operations:
http://groups.google.com/group/sage-support/browse_thread/thread/928840109cdadc6b/fd95901cea21288b?lnk=gst&q=pierre+steenrod#fd95901cea21288b I have completed my plan of converting my own results into SAGE: http://www-irma.u-strasbg.fr/~guillot/research/cohomology_of_groups/index.html It will look silly compared to Simon's ambitious programme, but at least there is a first version of a class representing unstable algebras (I certainly need help with that). To give you an idea, if the Small Groups library is installed you can go: sage: load "unstable_algebras.sage" sage: G= DihedralGroup(8) sage: A= UnstableCohomologyRing(G) sage: A Unstable Algebra over GF(2) generated by z, y, x subject to z*y + y^2 = 0. sage: A.degrees [1, 1, 2] sage: z, y, x = A.gens() sage: Sq(1) >> z z^2 (I would have prefered Sq(1) * z but somehow it didn't work, so I went for >>). For any group of order dividing 64 this will give you the mod 2 cohomology ring, from Carlson's computations; for about 90 groups among these, the Steenrod operations also work, as in the example above. If you want to avoid my UnstableAlgebra class, which isn't fully working yet, use CohomologyRing(G) instead. Any comments welcome. In fact there are a couple of questions in the .sage file, would be great if someone could help... Hope you enjoy this ! Pierre --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
