Piecewise convex embeddability on linear orders

Fuente: arXiv
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Main Authors: Iannella, Martina, Marcone, Alberto, Ros, Luca Motto, Weinstein, Vadim
Format: Preprint
Published: 2023
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author Iannella, Martina
Marcone, Alberto
Ros, Luca Motto
Weinstein, Vadim
author_facet Iannella, Martina
Marcone, Alberto
Ros, Luca Motto
Weinstein, Vadim
contents Given a nonempty set $\mathcal{L}$ of linear orders, we say that the linear order $L$ is $\mathcal{L}$-convex embeddable into the linear order $L'$ if it is possible to partition $L$ into convex sets indexed by some element of $\mathcal{L}$ which are isomorphic to convex subsets of $L'$ ordered in the same way. This notion generalizes convex embeddability and (finite) piecewise convex embeddability (both studied in arXiv:2309.09910), which are the special cases $\mathcal{L} = \{\mathbf{1}\}$ and $\mathcal{L} = \mathsf{Fin}$. We focus mainly on the behavior of these relations on the set of countable linear orders, first characterizing when they are transitive, and hence a quasi-order. We then study these quasi-orders from a combinatorial point of view, and analyze their complexity with respect to Borel reducibility. Finally, we extend our analysis to uncountable linear orders.
format Preprint
id arxiv_https___arxiv_org_abs_2312_01198
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Piecewise convex embeddability on linear orders
Iannella, Martina
Marcone, Alberto
Ros, Luca Motto
Weinstein, Vadim
Logic
Combinatorics
03E15, 06A05, 06A07
Given a nonempty set $\mathcal{L}$ of linear orders, we say that the linear order $L$ is $\mathcal{L}$-convex embeddable into the linear order $L'$ if it is possible to partition $L$ into convex sets indexed by some element of $\mathcal{L}$ which are isomorphic to convex subsets of $L'$ ordered in the same way. This notion generalizes convex embeddability and (finite) piecewise convex embeddability (both studied in arXiv:2309.09910), which are the special cases $\mathcal{L} = \{\mathbf{1}\}$ and $\mathcal{L} = \mathsf{Fin}$. We focus mainly on the behavior of these relations on the set of countable linear orders, first characterizing when they are transitive, and hence a quasi-order. We then study these quasi-orders from a combinatorial point of view, and analyze their complexity with respect to Borel reducibility. Finally, we extend our analysis to uncountable linear orders.
title Piecewise convex embeddability on linear orders
topic Logic
Combinatorics
03E15, 06A05, 06A07
url https://arxiv.org/abs/2312.01198