There are 4 new papers this time, from Blanc-Johnson-Turner, Clarke-Crossley-Whitehouse, Muro-Tonks, Ziemianski. I also wanted to say that in my paper of last time, there is an isomorphism between the completed E(n)-cohomology of X and Hom from the E(n)-homology of M_n X to an appropriate module. This isomorphism was known before to Greenlees, Hopkins, Sadofsky, and others, though it does not appear to be in print. The version of the paper now on the archive reflects that. Mark Hovey New papers appearing on hopf between 3/1/06 and 4/7/06 1. http://hopf.math.purdue.edu/cgi-bin/generate?/Blanc-Johnson-Turner/rdpa Title: On Realizing Diagrams of Pi-algebras Authors: David Blanc, Mark W. Johnson, and James M. Turner Abstract: Given a diagram of Pi-algebras (graded groups equipped with an action of the primary homotopy operations), we ask whether it can be realized as the homotopy groups of a diagram of spaces. The answer given here is in the form of an obstruction theory, of somewhat wider application, formulated in terms of generalized Pi-algebras. This extends a program begun by Dwyer, Kan, and Stover to study the realization of a single Pi-algebra. In particular, we explicitly analyze the simple case of a single map, and provide a detailed example, illustrating the connections to higher homotopy operations. 2. http://hopf.math.purdue.edu/cgi-bin/generate?/Clarke-Crossley-Whitehouse/ccwDiscrete The discrete module category for the ring of K-theory operations Francis Clarke, Martin Crossley, Sarah Whitehouse We study the category of discrete modules over the ring of degree zero stable operations in p-local complex K-theory. We show that the p-local K-homology of any space or spectrum is such a module, and that this category is isomorphic to a category defined by Bousfield and used in his work on the K-local stable homotopy category (Amer. J. Math., 1985). We also provide an alternative characterisation of discrete modules as locally finitely generated modules. 3. http://hopf.math.purdue.edu/cgi-bin/generate?/Muro-Tonks/1tK3 Title:The 1-type of a Waldhausen K-theory spectrum Authors: Fernando Muro and Andrew Tonks Abstract: We give a small functorial algebraic model for the 2-stage Postnikov section of the K-theory spectrum of a Waldhausen category and use our presentation to describe the multiplicative structure with respect to biexact functors. 4. http://hopf.math.purdue.edu/cgi-bin/generate?/Ziemianski/DI4Rep TITLE: A faithful unitary representation of the 2-compact group DI(4) AUTHOR: Krzysztof Ziemianski ABSTRACT: We construct a monomorphism from the $2$-compact group $DI(4)$ into a $2$-compact unitary group. ----------------