The canonical form, scissors congruence and adjoint degrees of polytopes

Fuente: arXiv
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Autori principali: Baumbach, Tom, Freyer, Ansgar, Weigert, Julian, Winter, Martin
Natura: Preprint
Pubblicazione: 2025
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author Baumbach, Tom
Freyer, Ansgar
Weigert, Julian
Winter, Martin
author_facet Baumbach, Tom
Freyer, Ansgar
Weigert, Julian
Winter, Martin
contents We study the canonical form $Ω$ as a valuation in the context of scissors congruence for polytopes. We identify the degree of its numerator - the adjoint polynomial $\operatorname{adj}_P$ - as an important invariant in this context. More precisely, for a polytope $P$ we define the degree drop that measures how much smaller than expected the degree of the adjoint polynomial of $P$ is. We show that this drop behaves well under various operations, such as decompositions, restrictions to faces, projections, products and Minkowski sums. Next we define the reduced canonical form $Ω_0$ and show that it is a translation-invariant 1-homogeneous valuation on polytopes that vanishes if and only if $P$ has positive degree drop. Using it we can prove that zonotopes can be characterized as the $d$-polytopes that have maximal possible degree drop $d-1$. We obtain a decomposition formula for $Ω_0$ that expresses it as a sum of edge-local quantities of $P$. Finally, we discuss valuations $Ω_s$ that can distinguish higher values of the degree drop.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04275
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The canonical form, scissors congruence and adjoint degrees of polytopes
Baumbach, Tom
Freyer, Ansgar
Weigert, Julian
Winter, Martin
Combinatorics
Algebraic Geometry
Metric Geometry
51M20, 52B45, 52B12, 14P05
We study the canonical form $Ω$ as a valuation in the context of scissors congruence for polytopes. We identify the degree of its numerator - the adjoint polynomial $\operatorname{adj}_P$ - as an important invariant in this context. More precisely, for a polytope $P$ we define the degree drop that measures how much smaller than expected the degree of the adjoint polynomial of $P$ is. We show that this drop behaves well under various operations, such as decompositions, restrictions to faces, projections, products and Minkowski sums. Next we define the reduced canonical form $Ω_0$ and show that it is a translation-invariant 1-homogeneous valuation on polytopes that vanishes if and only if $P$ has positive degree drop. Using it we can prove that zonotopes can be characterized as the $d$-polytopes that have maximal possible degree drop $d-1$. We obtain a decomposition formula for $Ω_0$ that expresses it as a sum of edge-local quantities of $P$. Finally, we discuss valuations $Ω_s$ that can distinguish higher values of the degree drop.
title The canonical form, scissors congruence and adjoint degrees of polytopes
topic Combinatorics
Algebraic Geometry
Metric Geometry
51M20, 52B45, 52B12, 14P05
url https://arxiv.org/abs/2508.04275