#### Title

Some Generalizations of Classical Integer Sequences Arising in Combinatorial Representation Theory

#### Publication Date

Fall 2020

#### Advisor(s) - Committee Chair

Molly Dunkum (Director), Rob Donnelly, Dominic Lanphier, and Tom Richmond

#### Degree Program

Department of Mathematics

#### Degree Type

Master of Science

#### Abstract

There exists a natural correspondence between the bases for a given finite-dimensional representation of a complex semisimple Lie algebra and a certain collection of finite edge-colored ranked posets, laid out by Donnelly, et al. in, for instance, [Don03]. In this correspondence, the Serre relations on the Chevalley generators of the given Lie algebra are realized as conditions on coeﬀicients assigned to poset edges. These conditions are the so-called diamond, crossing, and structure relations (hereinafter DCS relations.) New representation constructions of Lie algebras may thus be obtained by utilizing edge-colored ranked posets. Of particular combinatorial interest are those representations whose corresponding posets are distributive lattices. We study two families of such lattices, which we dub the generalized Fibonaccian lattices LFⁱᵇpn`1, kq and generalized Catalanian lattices LCᵃᵗpn, kq. These respectively generalize known families of lattices which are DCS-correspondent to some special families of representations of the classical Lie algebras An`₁ and Cn. We state and prove explicit formulae for the vertex cardinalities of these lattices; show existence and uniqueness of DCS-satisfactory edge coeﬀicients for certain values of n and k; and report on the eﬀicacy of various computational and algorithmic approaches to this problem. A Python library for computationally modeling and “solving” these lattices appears as an appendix.

#### Disciplines

Algebra | Discrete Mathematics and Combinatorics | Numerical Analysis and Scientific Computing

#### Recommended Citation

Malone, Sasha Verona, "Some Generalizations of Classical Integer Sequences Arising in Combinatorial Representation Theory" (2020). *Masters Theses & Specialist Projects.* Paper 3474.

https://digitalcommons.wku.edu/theses/3474

#### Included in

Algebra Commons, Discrete Mathematics and Combinatorics Commons, Numerical Analysis and Scientific Computing Commons

## Comments

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