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Francisco Kordon

Publications and source records attributed to Francisco Kordon.

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The integration problem for principal connections

In this paper we introduce the Integration Problem for principal connections. Just as a principal connection on a principal bundle $\phi:Q\rightarrow M$ may be used to split $TQ$ into horizontal and vertical subbundles, a discrete connection may be used to split $Q\times Q$ into horizontal and vertical submanifolds. All discrete connections induce a connection on the same principal bundle via a process known as the Lie or derivative functor. The Integration Problem consists of describing, for a principal connection $\mathcal{A}$, the set of all discrete connections whose associated connection is $\mathcal{A}$. Our first result is that for \emph{flat} principal connections, the Integration Problem has a unique solution among the \emph{flat} discrete connections. More broadly, under a fairly mild condition on the structure group $G$ of the principal bundle $\phi$, we prove that the existence part of the Integration Problem has a solution that needs not be unique. Last, we see that, when $G$ is abelian, given compatible continuous and discrete curvatures the Integration Problem has a unique solution constrained by those curvatures.

math.DG

Center and Lie algebra of outer derivations for algebras of differential operators associated to hyperplane arrangements

We compute the center and the Lie algebra of outer derivations of a familiy of algebras of differential operators associated to hyperplane arrangements of the affine space A 3. The results are completed for 4-braid arrangements and for reflection arrangements associated to the wreath product of a cyclic group with the symmetric group S 3. To achieve this we use tools from homological algebra and Lie-Rinehart algebras of differential operators.

math.KT

The Hochschild cohomology of the enveloping algebra of a Lie-Rinehart pair

Let $(S,L)$ be a Lie-Rinehart pair such that $L$ is $S$-projective and let $U$ be its universal enveloping algebra. The purpose of this paper is to present a spectral sequence which converges to the Hochschild cohomology of $U$ and whose second page involves the Lie-Rinehart cohomology of the pair and the Hochschild cohomology of $S$ with values on $U$.

math.KT

Lie-Rinehart and Hochschild cohomology for algebras of differential operators

Let $(S,L)$ be a Lie-Rinehart algebra such that $L$ is $S$-projective and let $U$ be its universal enveloping algebra. In this paper we present a spectral sequence which converges to the Hochschild cohomology of $U$ with values on a $U$-bimodule $M$ and whose second page involves the Lie-Rinehart cohomology of the algebra and the Hochschild cohomology of $S$ with values on $M$. After giving a convenient description of the involved algebraic structures we use the spectral sequence to compute explicitly the Hochschild cohomology of the algebra of differential operators tangent to a central arrangement of three lines.

math.KT

Hochschild cohomology of algebras of differential operators tangent to a central arrangement of lines

Given a central arrangement of lines $\mathcal{A}$ in a $2$-dimensional vector space $V$ over a field of characteristic zero, we study the algebra $\mathcal D(\mathcal A)$ of differential operators on $V$ which are logarithmic along $\mathcal A$. Among other things we determine the Hochschild cohomology of $\mathcal D(\mathcal A)$ as a Gerstenhaber algebra, establish a connection between that cohomology and the de Rham cohomology of the complement $M(\mathcal A)$ of the arrangement, determine the isomorphism group of $\mathcal D(\mathcal A)$ and classify the algebras of that form up to isomorphism.

math.KT