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Chern Characters for Twisted Matrix Factorizations and the Vanishing of the Higher Herbrand Difference

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 Added by Mark Walker
 Publication date 2014
  fields
and research's language is English




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We develop a theory of ``ad hoc Chern characters for twisted matrix factorizations associated to a scheme $X$, a line bundle ${mathcal L}$, and a regular global section $W in Gamma(X, {mathcal L})$. As an application, we establish the vanishing, in certain cases, of $h_c^R(M,N)$, the higher Herbrand difference, and, $eta_c^R(M,N)$, the higher codimensional analogue of Hochsters theta pairing, where $R$ is a complete intersection of codimension $c$ with isolated singularities and $M$ and $N$ are finitely generated $R$-modules. Specifically, we prove such vanishing if $R = Q/(f_1, dots, f_c)$ has only isolated singularities, $Q$ is a smooth $k$-algebra, $k$ is a field of characteristic $0$, the $f_i$s form a regular sequence, and $c geq 2$.



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We study matrix factorizations of locally free coherent sheaves on a scheme. For a scheme that is projective over an affine scheme, we show that homomorphisms in the homotopy category of matrix factorizations may be computed as the hypercohomology of a certain mapping complex. Using this explicit description, we give another proof of Orlovs theorem that there is a fully faithful embedding of the homotopy category of matrix factorizations into the singularity category of the corresponding zero subscheme. We also give a complete description of the image of this functor.
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