Title: Leibniz Formulas for Cyclic Homotopy Fixed Point Spectra Authors: Robert R. Bruner and John Rognes MSC-class: 19D55, 55P43, 55P91, 55S12, 55T05. ArXiv ID: math.AT/0406081 Addresses: Robert R. Bruner Department of Mathematics Wayne State University Detroit, Michigan 48067 USA rrb@math.wayne.edu John Rognes Department of Mathematics University of Oslo Box 1053, Blindern NO-0316 Oslo Norway rognes@math.uio.no Abstract: We analyze the homotopy fixed point spectrum of a circle-equivariant commutative S-algebra R in homological terms. There is a homological homotopy fixed point spectral sequence that converges conditionally to the continuous homology of the homotopy fixed point spectrum. We show that there are Dyer-Lashof operations Q^i acting on this algebra spectral sequence, and that its differentials are completely determined by those originating on the vertical axis. More surprisingly, we show that for each class x in the E^{2r}-term of the spectral sequence there are 2r other classes in the E^{2r}-term (obtained mostly by Dyer-Lashof operations on x) that are infinite cycles, i.e., survive to the E^infty-term. We apply this to completely determine the differentials in the homological homotopy fixed point spectral sequences for the topological Hochschild homology spectra R = THH(B) of many S-algebras, including B = MU, BP, ku, ko and tmf. Similar results apply for all finite subgroups of the circle, and for the Tate- and homotopy orbit spectra. This work is part of a homological approach to calculating topological cyclic homology and algebraic K-theory of commutative S-algebras.