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Main Authors: Stein, Dario, Széles, Márk
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2404.02017
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author Stein, Dario
Széles, Márk
author_facet Stein, Dario
Széles, Márk
contents We present a counterexample showing that Markov categories with conditionals (such as BorelStoch) need not validate a natural scheme of axioms which we call contraction identities. These identities hold in every traced monoidal category, so in particular this shows that BorelStoch cannot be embedded in any traced monoidal category. We remedy this under the additional assumption of atomicity: Atomic Markov categories validate all contraction identities, and furthermore admit a notion of trace defined for non-signalling morphisms. We conclude that atomic Markov categories admit an intrinsic calculus of combs without having to assume an embedding into a compact-closed category.
format Preprint
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institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Combs, Causality and Contractions in Atomic Markov Categories
Stein, Dario
Széles, Márk
Category Theory
We present a counterexample showing that Markov categories with conditionals (such as BorelStoch) need not validate a natural scheme of axioms which we call contraction identities. These identities hold in every traced monoidal category, so in particular this shows that BorelStoch cannot be embedded in any traced monoidal category. We remedy this under the additional assumption of atomicity: Atomic Markov categories validate all contraction identities, and furthermore admit a notion of trace defined for non-signalling morphisms. We conclude that atomic Markov categories admit an intrinsic calculus of combs without having to assume an embedding into a compact-closed category.
title Combs, Causality and Contractions in Atomic Markov Categories
topic Category Theory
url https://arxiv.org/abs/2404.02017