Subject: new Hopf listings From: Mark Hovey Date: 05 Nov 2006 09:09:17 -0500 There are 4 new papers this time, from Chebolu-Christensen-Minac, DavisDaniel, Stacey-Whitehouse, and Yagita. Mark Hovey New papers appearing on hopf between 10/6/06 and 11/5/06 1. http://hopf.math.purdue.edu/cgi-bin/generate?/Chebolu-Christensen-Minac/GH-StMod TITLE: Groups which do not admit ghosts AUTHORS: Sunil K. Chebolu, J. Daniel Christensen, and Jan Minac Department of Mathematics University of Western Ontario London, ON N6A 5B7, Canada AMS Subject classsification: Primary 20C20, 20J06; Secondary 55P42 ABSTRACT: A ghost in the stable module category of a group G is a map between representations of G that is invisible to Tate cohomology. We show that the only non-trivial finite p-groups whose stable module categories have no non-trivial ghosts are the cyclic groups of order 2 and 3. We compare this to the situation in the derived category of a commutative ring. 2. http://hopf.math.purdue.edu/cgi-bin/generate?/DavisDaniel/siterplusg Title: The site R^+_G for a profinite group G Author: Daniel G. Davis AMS classification number: 55P42, 55U35, 18B25 Abstract: Let G be a non-finite profinite group and let G-Sets_{df} be the canonical site of finite discrete G-sets. Then the category R^+_G, defined by Devinatz and Hopkins, is the category obtained by considering G-Sets_{df} together with the profinite G-space G itself, with morphisms being continuous G-equivariant maps. We show that R^+_G is a site when equipped with the pretopology of epimorphic covers. Also, we explain why the associated topology on R^+_G is not subcanonical, and hence, not canonical. We note that, since R^+_G is a site, there is automatically a model category structure on the category of presheaves of spectra on the site. Finally, we point out that such presheaves of spectra are a nice way of organizing the data that is obtained by taking the homotopy fixed points of a continuous G-spectrum with respect to the open subgroups of G. 3. http://hopf.math.purdue.edu/cgi-bin/generate?/Stacey-Whitehouse/deloopv2 Title: Stable and Unstable Operations in mod p Cohomology Theories Authors: Andrew Stacey and Sarah Whitehouse AMS classification number: 55S25, 55P47 Other useful information: math.AT/0605471 Abstract: We consider operations between two multiplicative, complex orientable cohomology theories. Under suitable hypotheses, we construct a map from unstable to stable operations, left-inverse to the usual map from stable to unstable operations. In the main example, where the target theory is one of the Morava K-theories, this provides a simple and explicit description of a splitting arising from the Bousfield-Kuhn functor. This is an updated version of an earlier submission. The proof of proposition 3.2 has been corrected; other minor improvements have been made. 4. http://hopf.math.purdue.edu/cgi-bin/generate?/Yagita/abp Algebraic BP-theory and norm varieties Nobuaki Yagita Department of Mathematics, Faculty of Education, Ibaraki University, Mito, Ibaraki, Japan Primary 14C15, 57T25; Secondary 55R35, 57T05 Let X be a smooth variety over a field k of characteristic zero. For a fixed prime p, the algebraic BP-theory ABP(X) is the algebraic version of the topological BP-theory. Given a nonzero symbol a in K_{n+1}^M (k)/p, the norm variety V_a is a variety such that a=0 in K_{n+1}^M (k(V_a))/p and V_a(C)=v_n. In this paper, we mainly study ABP(V_a) for p an odd prime. ---------------------Instructions----------------------------- To subscribe or unsubscribe to this list, send a message to Don Davis at dmd1@lehigh.edu with your e-mail address and name. Please make sure he is using the correct e-mail address for you. To see past issues of this mailing list, point your WWW browser to http://math.wesleyan.edu/~mhovey/archive/ If this doesn't work or is missing a few issues, try http://www.lehigh.edu/~dmd1/algtop.html which also has the other messages sent to Don's list. To get the papers listed above, point your Web browser to the URL listed. The general Hopf archive URL is http://hopf.math.purdue.edu There is a web form for submitting papers to Hopf on this site as well. You should submit an abstract as well. Clarence has explicit instructions for the form of this abstract: see http://hopf.math.purdue.edu/new-html/submissions.html In particular, your abstract is meant to be read by humans, so should be as readable as possible. I reserve the right to edit unreadable abstracts. You should then e-mail Clarence at wilker at math.purdue.edu telling him what you have uploaded. The largest archive of math preprints is at http://arxiv.gov There is an algebraic topology section in this archive. The most useful way to browse it or submit papers to it is via the front end developed by Greg Kuperberg: http://front.math.ucdavis.edu To get the announcements of new papers in the algebraic topology section at the arXiv, send e-mail to math@arxiv.org with subject line "subscribe" (without quotes), and with the body of the message "add AT" (without quotes). I am solely responsible for these messages---don't send complaints about them to Clarence. Thanks to Clarence for creating and maintaining the archive.