arXiv subjects

Aaron Lauve

Publications and source records attributed to Aaron Lauve.

26 records · Page 2Linked to original sources

arXiv2009

New Hopf Structures on Binary Trees (Extended Abstract)

The multiplihedra {M_n} form a family of polytopes originating in the study of higher categories and homotopy theory. While the multiplihedra may be unfamiliar to the algebraic combinatorics community, it is nestled between two families of polytopes that certainly are not: the permutahedra {S_n} and associahedra {Y_n}. The maps between these families reveal several new Hopf structures on tree-like objects nestled between the Malvenuto-Reutenauer (MR) Hopf algebra of permutations and the Loday-Ronco (LR) Hopf algebra of planar binary trees. We begin their study here, constructing a module over MR and a Hopf module over LR from the multiplihedra. Rich structural information about this module is uncovered via a change of basis--using Möbius inversion in posets built on the 1-skeleta of the {M_n}. Our analysis uses the notion of an interval retract, which should have independent interest in poset combinatorics. It also reveals new families of polytopes, and even a new factorization of a known projection from the associahedra to hypercubes.

math.CO↗

arXiv2009

A class of left quantum groups modeled after SL_q(n)

For each n >1, we construct a left quantum group, i.e., a left Hopf algebra H generated by comatrix units X_{ij} and modeled after SL_q(n), which has a left antipode but no right antipode. The quantum special linear group SL_q(n) is a homomorphic image of our H.

math.QA↗

arXiv2009

Hopf quivers and Nichols algebras in positive characteristic

We apply a combinatorial formula of the first author and Rosso, for products in Hopf quiver algebras, to determine the structure of Nichols algebras. We illustrate this technique by explicitly constructing new examples of Nichols algebras in positive characteristic. We further describe the corresponding Radford biproducts and some liftings of these biproducts, which are new finite dimensional pointed Hopf algebras.

math.QA↗

arXiv2007

A note on the Markoff condition and central words

We define Markoff words as certain factors appearing in bi-infinite words satisfying the Markoff condition. We prove that these words coincide with central words, yielding a new characterization of Christoffel words.

math.CO↗

arXiv2006

Quasideterminants and q-commuting minors

We present two new proofs of the the important q-commuting property holding among certain pairs of quantum minors of an n x n q-generic matrix. The first uses elementary quasideterminantal arithmetic; the second involves paths in an edge-weighted directed graph.

math.QA↗

arXiv2006

Quantum- and Quasi-Plucker Coordinates

We demonstrate a passage from the "quasi-Plucker coordinates" of Gelfand and Retakh, to the quantum Plucker coordinates built from q-generic matrices. In the process, we rediscover the defining relations of the quantum Grassmannian of Taft and Towber and provide that algebra with more concrete geometric origins.

math.QA↗

arXiv2006

Flag varieties for the Yangian Y(gl_n)

We show that the Yangian Yn over gl_n possesses some features of the ring of regular functions on GL_n. In particular, we use the theory of quasideterminants to construct noncommutative flags associated to Yn. In so doing, a class of comodule algebras Fl(γ) for Yn (viewed as C[GL_n]) is revealed. As in the classic case, these flag algebras are related to the irreducible representations of Yn (viewed as U(gl_n)). In the course of defining the rings Fl(γ), connections to the new parabolic presentations of Yn given by Brundan and Kleshchev (2005) are uncovered.

math.QA↗

arXiv2004

NSym into Q_{\infty} is not a Hopf Map

There is a natural algebra map (in fact, embedding) from the noncommutative symmetric functions NSym to the quadratic algebra Q_{\infty} of pseudoroots of polynomials. In this note, I show that it is not a coalgebra map. Hence, the Hopf algebra structure on NSym can't be extended to this important larger algebra.

math.RA↗