arXiv subjects

Brett Milburn

Publications and source records attributed to Brett Milburn.

4 recordsLinked to original sources

arXiv2012

Abelian Groups in omega-categories

We study abelian group objects in $ω$-categories and discuss the well-known Dold-Kan correspondence from the perspective of $ω$-categories as a model for strict $\infty$-categories. The first part of the paper is intended to compile results from the existing literature and to fill some gaps therein. We go on to consider a parameterized Dold-Kan correspondence, i.e. a Dold-Kan correspondence for presheaves of $ω$-categories. The main result is to describe the descent or sheaf condition in terms of a glueing condition that is familiar for 1 and 2-stacks.

math.CT↗

arXiv2011

The Quotient of a Category by the Action of a Monoidal Category

We introduce the notion of the quotient of a category $C$ by the action $A : M \longrightarrow C \times C$ of a unital symmetric monoidal category $M$. The quotient $C/M$ is a 2-category. We prove its existence and uniqueness by first showing that every small 2-category has a presentation in terms of generators and relations and then describing the generators and relations needed for the quotient $C/M$.

math.CT↗

arXiv2010

Generalized Complex and Dirac Structures on Homogeneous Spaces

We partially describe equivariant Dirac and generalized complex structures on a homogeneous space $G/K$ by giving equivalent data involving only the Lie algebra. We consider real semisimple adjoint orbits in any semisimple Lie algebra over $\mathbb R$ and real nilpotent orbits in $sl_n (\mathbb R)$. We give a complete classification for Riemannian symmetric spaces and for a compact group modulo a closed, connected subgroup containing a Cartan subgroup.

math.DG↗

arXiv2010

Two Categories of Dirac Manifolds

We define two categories of Dirac manifolds, i.e. manifolds with complex Dirac structures. The first notion of maps I call \emph{Dirac maps}, and the category of Dirac manifolds is seen to contain the categories of Poisson and complex manifolds as full subcategories. The second notion, \emph{dual-Dirac maps}, defines a \emph{dual-Dirac category} which contains presymplectic and complex manifolds as full subcategories. The dual-Dirac maps are stable under B-transformations. In particular we get two structures of a category on Hitchin'sgeneralized complex manifolds, i.e., two reasonable notions of generalized complex maps. We also generalize further to get categories of Dirac manifolds for which the Dirac structures lie in arbitrary exact Courant algebroids. As an example, we consider the case of a Lie group with a complex Dirac structure and establish conditions for which multiplication is a Dirac map.

math.DG↗