The unreasonable ubiquitousness of quasi-polynomials

A function $g$, with domain the natural numbers, is a quasi-polynomial if there exists a period $m$ and polynomials $p_0,p_1,\ldots,p_m-1$ such that $g(t)=p_i(t)$ for $t\equiv i\bmod m$. Quasi-polynomials classically – and ``reasonably'' – appear in Ehrhart theory and in other contexts whe...

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Main Author: Kevin Woods
Format: Article
Language:English
Published: Discrete Mathematics & Theoretical Computer Science 2013-01-01
Series:Discrete Mathematics & Theoretical Computer Science
Subjects:
Online Access:https://dmtcs.episciences.org/2335/pdf
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author Kevin Woods
author_facet Kevin Woods
author_sort Kevin Woods
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description A function $g$, with domain the natural numbers, is a quasi-polynomial if there exists a period $m$ and polynomials $p_0,p_1,\ldots,p_m-1$ such that $g(t)=p_i(t)$ for $t\equiv i\bmod m$. Quasi-polynomials classically – and ``reasonably'' – appear in Ehrhart theory and in other contexts where one examines a family of polyhedra, parametrized by a variable t, and defined by linear inequalities of the form $a_1x_1+⋯+a_dx_d≤ b(t)$. Recent results of Chen, Li, Sam; Calegari, Walker; and Roune, Woods show a quasi-polynomial structure in several problems where the $a_i$ are also allowed to vary with $t$. We discuss these ``unreasonable'' results and conjecture a general class of sets that exhibit various (eventual) quasi-polynomial behaviors: sets $S_t$ that are defined with quantifiers $(\forall , ∃)$, boolean operations (and, or, not), and statements of the form $a_1(t)x_1+⋯+a_d(t)x_d ≤ b(t)$, where $a_i(t)$ and $b(t)$ are polynomials in $t$. These sets are a generalization of sets defined in the Presburger arithmetic. We prove several relationships between our conjectures, and we prove several special cases of the conjectures.
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spelling doaj.art-0931abc6d141454083ceb6ef3f5883272024-03-07T14:52:36ZengDiscrete Mathematics & Theoretical Computer ScienceDiscrete Mathematics & Theoretical Computer Science1365-80502013-01-01DMTCS Proceedings vol. AS,...Proceedings10.46298/dmtcs.23352335The unreasonable ubiquitousness of quasi-polynomialsKevin Woods0Oberlin CollegeA function $g$, with domain the natural numbers, is a quasi-polynomial if there exists a period $m$ and polynomials $p_0,p_1,\ldots,p_m-1$ such that $g(t)=p_i(t)$ for $t\equiv i\bmod m$. Quasi-polynomials classically – and ``reasonably'' – appear in Ehrhart theory and in other contexts where one examines a family of polyhedra, parametrized by a variable t, and defined by linear inequalities of the form $a_1x_1+⋯+a_dx_d≤ b(t)$. Recent results of Chen, Li, Sam; Calegari, Walker; and Roune, Woods show a quasi-polynomial structure in several problems where the $a_i$ are also allowed to vary with $t$. We discuss these ``unreasonable'' results and conjecture a general class of sets that exhibit various (eventual) quasi-polynomial behaviors: sets $S_t$ that are defined with quantifiers $(\forall , ∃)$, boolean operations (and, or, not), and statements of the form $a_1(t)x_1+⋯+a_d(t)x_d ≤ b(t)$, where $a_i(t)$ and $b(t)$ are polynomials in $t$. These sets are a generalization of sets defined in the Presburger arithmetic. We prove several relationships between our conjectures, and we prove several special cases of the conjectures.https://dmtcs.episciences.org/2335/pdfquasi-polynomialsehrhart theorypresburger arithmeticrational generating functions[info.info-dm] computer science [cs]/discrete mathematics [cs.dm]
spellingShingle Kevin Woods
The unreasonable ubiquitousness of quasi-polynomials
Discrete Mathematics & Theoretical Computer Science
quasi-polynomials
ehrhart theory
presburger arithmetic
rational generating functions
[info.info-dm] computer science [cs]/discrete mathematics [cs.dm]
title The unreasonable ubiquitousness of quasi-polynomials
title_full The unreasonable ubiquitousness of quasi-polynomials
title_fullStr The unreasonable ubiquitousness of quasi-polynomials
title_full_unstemmed The unreasonable ubiquitousness of quasi-polynomials
title_short The unreasonable ubiquitousness of quasi-polynomials
title_sort unreasonable ubiquitousness of quasi polynomials
topic quasi-polynomials
ehrhart theory
presburger arithmetic
rational generating functions
[info.info-dm] computer science [cs]/discrete mathematics [cs.dm]
url https://dmtcs.episciences.org/2335/pdf
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