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arXiv · 1504.07164

The Jacobian module, the Milnor fiber, and the $D$-module generated by $f^s$

Uli Walther
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Abstract

For a germ $f$ on a complex manifold $X$, we introduce a complex derived from the Liouville form acting on logarithmic differential forms, and give an exactness criterion. We use this Liouville complex to connect properties of the $D$-module generated by $f^s$ to homological data of the Jacobian ideal; specifically we show that for a large class of germs the annihilator of $f^s$ is generated by derivations. Through local cohomology, we connect the cohomology of the Milnor fiber to the Jacobian module via logarithmic differentials. In particular, we consider (not necessarily reduced) hyperplane arrangements: we prove a conjecture of Terao on the annihilator of $1/f$; we confirm in many cases a corresponding conjecture on the annihilator of $f^s$ but we disprove it in general; we show that the Bernstein--Sato polynomial of an arrangement is not determined by its intersection lattice; we prove that arrangements for which the annihilator of $f^s$ is generated by derivations fulfill the Strong Monodromy Conjecture, and that this includes as very special cases all arrangements of Coxeter and of crystallographic type, and all multi-arrangements in dimension 3.

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Uli Walther. 2015-04-27. The Jacobian module, the Milnor fiber, and the $D$-module generated by $f^s$. https://doi.org/10.1007/s00222-016-0684-2

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