Finite models for positive combinatorial and exponential algebra

Fuente: arXiv
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Main Authors: Alsulami, Tumadhir, Jackson, Marcel
Format: Preprint
Published: 2024
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author Alsulami, Tumadhir
Jackson, Marcel
author_facet Alsulami, Tumadhir
Jackson, Marcel
contents We use high girth, high chromatic number hypergraphs to show that there are finite models of the equational theory of the semiring of nonnegative integers whose equational theory has no finite axiomatisation, and show this also holds if factorial, fixed base exponentiation and operations for binomial coefficients are adjoined. We also derive the decidability of the equational logical entailment operator $\vdash$ for antecedents true on $\mathbb{N}$ by way of a form of the finite model property. Two appendices contain additional basic development of combinatorial operations. Amongst the observations are an eventual dominance well-ordering of combinatorial functions and consequent representation of the ordinal $ε_0$ in terms of factorial functions; the equivalence of the equational logic of combinatorial algebra over the natural numbers and over the positive reals; and a candidate list of elementary axioms.
format Preprint
id arxiv_https___arxiv_org_abs_2411_05101
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Finite models for positive combinatorial and exponential algebra
Alsulami, Tumadhir
Jackson, Marcel
Logic
08B05, 03C10, 03C05, 03E10
We use high girth, high chromatic number hypergraphs to show that there are finite models of the equational theory of the semiring of nonnegative integers whose equational theory has no finite axiomatisation, and show this also holds if factorial, fixed base exponentiation and operations for binomial coefficients are adjoined. We also derive the decidability of the equational logical entailment operator $\vdash$ for antecedents true on $\mathbb{N}$ by way of a form of the finite model property. Two appendices contain additional basic development of combinatorial operations. Amongst the observations are an eventual dominance well-ordering of combinatorial functions and consequent representation of the ordinal $ε_0$ in terms of factorial functions; the equivalence of the equational logic of combinatorial algebra over the natural numbers and over the positive reals; and a candidate list of elementary axioms.
title Finite models for positive combinatorial and exponential algebra
topic Logic
08B05, 03C10, 03C05, 03E10
url https://arxiv.org/abs/2411.05101