Enumeration of lattices of nullity $k$ and containing $r$ comparable reducible elements

Fuente: arXiv
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Main Author: Bhavale, A. N.
Format: Preprint
Published: 2025
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author Bhavale, A. N.
author_facet Bhavale, A. N.
contents In 2002 Thakare et al.\ counted non-isomorphic lattices on $n$ elements, having nullity up to two. In 2020 Bhavale and Waphare introduced the concept of RC-lattices as the class of all lattices in which all the reducible elements are comparable. In this paper, we enumerate all non-isomorphic RC-lattices on $n$ elements. For this purpose, firstly we enumerate all non-isomorphic RC-lattices on $n \geq 4$ elements, having nullity $k \geq 1$, and containing $2 \leq r \leq 2k$ reducible elements. Secondly we enumerate all non-isomorphic RC-lattices on $n \geq 4$ elements, having nullity $k \geq 1$. This work is in respect of Birkhoff's open problem of enumerating all finite lattices on $n$ elements.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06912
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enumeration of lattices of nullity $k$ and containing $r$ comparable reducible elements
Bhavale, A. N.
Combinatorics
06A05, 06A06, 06A07
In 2002 Thakare et al.\ counted non-isomorphic lattices on $n$ elements, having nullity up to two. In 2020 Bhavale and Waphare introduced the concept of RC-lattices as the class of all lattices in which all the reducible elements are comparable. In this paper, we enumerate all non-isomorphic RC-lattices on $n$ elements. For this purpose, firstly we enumerate all non-isomorphic RC-lattices on $n \geq 4$ elements, having nullity $k \geq 1$, and containing $2 \leq r \leq 2k$ reducible elements. Secondly we enumerate all non-isomorphic RC-lattices on $n \geq 4$ elements, having nullity $k \geq 1$. This work is in respect of Birkhoff's open problem of enumerating all finite lattices on $n$ elements.
title Enumeration of lattices of nullity $k$ and containing $r$ comparable reducible elements
topic Combinatorics
06A05, 06A06, 06A07
url https://arxiv.org/abs/2502.06912