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Autores principales: Huang, Hau-Wen, Wen, Chia-Yi
Formato: Preprint
Publicado: 2024
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Acceso en línea:https://arxiv.org/abs/2406.13455
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author Huang, Hau-Wen
Wen, Chia-Yi
author_facet Huang, Hau-Wen
Wen, Chia-Yi
contents From the viewpoint of Johnson graphs as slices of a hypercube, we derive a novel algebra homomorphism $\sharp$ from the universal Racah algebra $\Re$ into $U(\mathfrak{sl}_2)$. We use the Casimir elements of $\Re$ to describe the kernel of $\sharp$. By pulling back via $\sharp$ every $U(\mathfrak{sl}_2)$-module can be viewed as an $\Re$-module. We show that for any finite-dimensional $U(\mathfrak{sl}_2)$-module $V$, the $\Re$-module $V$ is completely reducible and three generators of $\Re$ act on every irreducible $\Re$-submodule of $V$ as a Leonard triple. In particular, Leonard triples can be constructed in terms of the second dual distance operator of the hypercube $H(D,2)$ and a decomposition of the second distance operator of $H(D,2)$ induced by Johnson graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2406_13455
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Johnson graphs as slices of a hypercube and an algebra homomorphism from the universal Racah algebra into $U(\mathfrak{sl}_2)$
Huang, Hau-Wen
Wen, Chia-Yi
Combinatorics
Representation Theory
05E30, 16G30, 16S30, 33D45
From the viewpoint of Johnson graphs as slices of a hypercube, we derive a novel algebra homomorphism $\sharp$ from the universal Racah algebra $\Re$ into $U(\mathfrak{sl}_2)$. We use the Casimir elements of $\Re$ to describe the kernel of $\sharp$. By pulling back via $\sharp$ every $U(\mathfrak{sl}_2)$-module can be viewed as an $\Re$-module. We show that for any finite-dimensional $U(\mathfrak{sl}_2)$-module $V$, the $\Re$-module $V$ is completely reducible and three generators of $\Re$ act on every irreducible $\Re$-submodule of $V$ as a Leonard triple. In particular, Leonard triples can be constructed in terms of the second dual distance operator of the hypercube $H(D,2)$ and a decomposition of the second distance operator of $H(D,2)$ induced by Johnson graphs.
title Johnson graphs as slices of a hypercube and an algebra homomorphism from the universal Racah algebra into $U(\mathfrak{sl}_2)$
topic Combinatorics
Representation Theory
05E30, 16G30, 16S30, 33D45
url https://arxiv.org/abs/2406.13455