Thomas Willwacher

  1. The cubical complex of a permutation group representation - or however you want to call it.

    Authors: Pavol Severa, Thomas Willwacher
    Subjects: Quantum Algebra
    Abstract

    This paper is about a small combinatorial trick, which is well known, but has
    no name. Let G be a permutation group acting on a vector space M. There is a
    natural way to assign a cosimplicial space to these data. We call the resulting
    cochain complex the cubical complex. Its cohomology is easy to compute. We give
    some examples of its occurrence in nature.

  2. M. Kontsevich's graph complex and the Grothendieck-Teichmueller Lie algebra.

    Authors: Thomas Willwacher
    Subjects: Quantum Algebra
    Abstract

    We show that the zeroth cohomology of Kontsevich's graph complex is
    isomorphic to the Grothendieck-Teichm\"uller Lie algebra grt. The map is
    explicitly described. This result has applications to deformation quantization
    and Duflo theory. Also, it allows proving the freeness part of the
    Deligne-Drinfeld conjecture in some low orders. As a side result one obtains
    that the homotopy deformations of the Gerstenhaber operad are parameterized by
    grt. Finally, our methods give a second proof of a result of H.

  3. A note on the Koszul complex in deformation quantization.

    Authors: Andrea Ferrario, Carlo A. Rossi, Thomas Willwacher
    Subjects: Quantum Algebra
    Abstract

    The aim of this short note is to present a proof of Conjecture 1.3 of
    \cite{CFFR} about the existence of an $A_\infty$-quasi-isomorphism between the
    $A_\infty$-$\mathrm S(V^*)$-$\wedge(V)$-bimodule $K$, introduced in
    \cite{CFFR}, and the Koszul complex $\mathrm K(V)$ of $\mathrm S(V^*)$, viewed
    as a $\mathrm S(V^*)$-$\wedge(V)$-bimodule, for $V$ a finite-dimensional
    (complex or real) vector space.

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