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Christopher Tropp

Publications and source records attributed to Christopher Tropp.

3 recordsLinked to original sources

A Picard-Theoretic Brauer Object for Derived Smooth Manifolds

Let $X=(|X|,\mathcal O_X)$ be a derived smooth manifold in the sense of Spivak. After passing from the simplicial $C^\infty$-structure sheaf to a connective spectral structure sheaf $\mathbb O_X$, we construct the intrinsic Picard hypersheaf of invertible $\mathbb O_X$-modules and define its delooping \[ \operatorname{Br}^{\mathrm{Pic}}_X :=B\operatorname{Pic}_{\mathbb O_X}. \] On the ordinary open site of $|X|$, we prove an equivalence of hypersheaves of connected pointed spaces \[ \operatorname{Br}^{\mathrm{Pic}}_X \simeq K(\underline{\mathbb Z},1) \times B^2\operatorname{GL}_1(\mathbb O_X). \] The statement is unconditional at the level of Picard torsors. Its interpretation as a classification of forms of the module category is made under an explicit category-valued open-hyperdescent hypothesis, and representability by an internal $E_1$-algebra is separated further by a global compact-local-generator hypothesis together with internal mapping objects, their base-change equivalences, and relative Morita continuity. For an ordinary paracompact smooth manifold $M$, the real and complex coefficient theories recover, respectively, the pointed-set decompositions \[ H^1_{\mathrm{sing}}(M;\mathbb Z) \times H^2_{\mathrm{sing}}(M;\mathbb Z/2) \quad\text{and}\quad H^1_{\mathrm{sing}}(M;\mathbb Z) \times H^3_{\mathrm{sing}}(M;\mathbb Z). \]

math.GM

A Unified Variational Framework for Planar Elastica with General Distributed Loads

We present a simple variational framework for planar elastica that enables distributed energies, such as gravitational loading or magnetic body torques, to be incorporated in a modular and unified manner. The formulation is based on expressing all load induced contributions directly at the level of the energy functional, which avoids the force balance constructions used in classical treatments such as Wang (1986) and makes the inclusion of additional physical effects straightforward. The resulting planar energy functional yields compact governing equations in which the contributions of individual load types remain clearly separated. We demonstrate that the framework reproduces the classical heavy elastica equations exactly and naturally accommodates magnetic energy terms commonly used in hard magnetic rod models. Although mathematically elementary, the formulation provides a clean and extensible structure for describing planar rod deformations under general distributed loads.

physics.class-ph

A Serre-Swan theorem for gerbe modules on étale Lie groupoids

Given a bundle gerbe on a compact smooth manifold or, more generally, on a compact étale Lie groupoid $M$, we show that the corresponding category of gerbe modules, if it is non-trivial, is equivalent to the category of finitely generated projective modules over an Azumaya algebra on $M$. This result can be seen as an equivariant Serre-Swan theorem for twisted vector bundles.

math.AT