arXiv subjects

Jorge Becerra

Publications and source records attributed to Jorge Becerra.

8 recordsLinked to original sources

arXiv2026

Knot invariants from XC-structures on the Sweedler algebra are trivial

An XC-algebra is the minimum algebraic structure needed to define a framed, oriented knot invariant and generalises Lawrence's invariant obtained from ribbon Hopf algebras. In this note, we show that the knot invariant produced by any XC-structure on the Sweedler algebra is completely determined by the framing of the knot. Furthermore, we also exhibit explicit families of XC-structures on the Sweedler algebra that do not have a ribbon Hopf-algebraic origin.

math.GT↗

arXiv2025

Pivotal Module Categories, Factorization Homology and Modular Invariant Modified Traces

The algebraic notion of a pivotal module category was developed by Schaumann and Shimizu and is central to the description of boundary conditions in conformal field theory according to a proposal by Fuchs and Schweigert. In this paper, we present a large class of examples of pivotal module categories of topological origin: For a unimodular finite ribbon category $\mathcal{A}$, we prove that the factorization homology $\int_\Sigma \mathcal{A}$ of a compact oriented surface $\Sigma$ with $n$ marked boundary intervals, at least one per connected component, comes with the structure of a pivotal module category over $\mathcal{A}^{\boxtimes n}$. This endows the internal skein algebras of Ben-Zvi-Brochier-Jordan, in particular the elliptic double, with a symmetric Frobenius structure. As application, we obtain, for each choice of $\mathcal{A}$, a family of full open conformal field theories, each of which comes with correlation functions for all surfaces with marked boundary intervals that are explicitly computable using factorization homology. As a further application, we explain how modified traces can be 'integrated' over surfaces: We show that the modified trace for $\mathcal{A}$ extends in a canonical way to the factorization homology of $\Sigma$. The resulting traces have the remarkable property of being modular invariant, i.e. fixed by the mapping class group action.

math.QA↗

arXiv2025

XC-tangles and universal invariants

We introduce a class of decorated abstract graphs, that we call XC-tangles, that provides a very convenient framework to study quantum invariants of tangles and virtual tangles. These can be viewed as a far-reaching generalisation of rotational tangle diagrams for (virtual) upwards tangles, and constitute the topological analogue of XC-algebras, the minimum algebraic structure needed to construct an knot isotopy invariant following the construction of Lawrence and Lee. XC-tangles admit a very natural description in terms of the so-called XC-Gauss diagrams, and this equivalence lifts the well-known equivalence between virtual upwards tangles and upwards Gauss diagrams. For every XC-algebra $A$, there is a naturally defined strict monoidal full functor $Z_A: \mathcal{T}^{\mathrm{XC}} \rightarrow v\mathcal{E}(A)$ from the category of XC-tangles to the "virtual category of elements of $A$". When $A$ is the endomorphism algebra of a finite-dimensional representation of a ribbon Hopf algebra, this functor can be viewed as an extension of the corresponding Reshetikhin-Turaev functor. Lastly, we also initiate the study of a theory of finite type invariants for one-component XC-tangles that lifts that for virtual long knots.

math.GT↗

arXiv2025

Minimal generating sets of rotational Reidemeister moves

Rotational tangle diagrams have been proven to be extremely important in the study of quantum invariants, as they provide a natural passage between topology and quantum algebra. In this paper, we give a detailed description of several generating sets of rotational Reidemeister moves for rotational diagrams of both unframed and framed tangles. In particular, we prove that the minimal number of moves needed to generate all oriented unframed (resp. framed) rotational Reidemeister moves is 8 (resp. 9). The latter implies that a minimal generating set of Reidemeister moves for oriented, framed links contains 5 moves.

math.GT↗

arXiv2025

A refined functorial universal tangle invariant

The universal invariant with respect to a given ribbon Hopf algebra is a tangle invariant that dominates all the Reshetikhin-Turaev invariants built from the representation theory of the algebra. We construct a canonical strict monoidal functor that encodes the universal invariant of upwards tangles and refines the Kerler-Kauffman-Radford functorial invariant. Moreover, this functor preserves the braiding, twist and the open trace, the latter being a mild modification of Joyal-Street-Verity's notion of trace in a balanced category. We construct this functor using the more flexible XC-algebras, a class which contains both ribbon Hopf algebras and endomorphism algebras of representation of these.

math.GT↗

arXiv2023

Strictification and non-strictification of monoidal categories

In this survey paper we give account of several approaches to the strictification and non-strictification of monoidal categories, which are constructions that turn a monoidal category into a (non-)strict one monoidally equivalent to the original category, and how they are related to analogous notions in higher categorical structures. We first provide explicit, elementary models for the (non-)strictification and show that these two constructions give the free (non-)strict monoidal category generated by a monoidal category. Moreover, we prove in detail that these two constructions are part of a pair of free-forgetful 2-adjunctions. We later show that these constructions can be recovered from Power's general coherence theorem for 2-monads. Lastly we describe another model for the strictification based on right-module endofunctors and provide a detailed, self-contained proof that this is a particular instance of strictification of bicategories via the bicategorical analogue of the Yoneda embedding.

math.CT↗

arXiv2023

On Bar-Natan - van der Veen's perturbed Gaussians

We elucidate further properties of the novel family of polynomial time knot polynomials devised by Bar-Natan and van der Veen based on the Gaussian calculus of generating series for noncommutative algebras. These polynomials determine all coloured Jones polynomials and the simplest of these is expected to coincide with the one-variable 2-loop polynomial. We prove a conjecture stating that half of these polynomials vanish and give concrete formulas for three of these knot polynomial invariants. We also study the behaviour of these polynomials under the connected sum of knots.

math.GT↗

arXiv2021

A combinatorial PROP for bialgebras

It is a classical result that the category of finitely-generated free monoids serves as a PROP for commutative bialgebras. Attaching permutations to fix the order of multiplication, we construct an extension of this category that is equivalent to the PROP for bialgebras.

math.CT↗