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Documents authored by Hirata, Michikazu


Document
A Formalization of the Lévy-Prokhorov Metric in Isabelle/HOL

Authors: Michikazu Hirata

Published in: LIPIcs, Volume 309, 15th International Conference on Interactive Theorem Proving (ITP 2024)


Abstract
The Lévy-Prokhorov metric is a metric between finite measures on a metric space. The metric was introduced to analyze weak convergence of measures. We formalize the Lévy-Prokhorov metric and prove Prokhorov’s theorem in Isabelle/HOL. Prokhorov’s theorem provides a condition for the relative compactness of sets of finite measures and plays essential roles in proofs of the central limit theorem, Sanov’s theorem in large deviation theory, and the existence of optimal coupling in transportation theory. Our formalization includes important results in mathematics such as the Riesz representation theorem, which is a theorem in functional analysis and used to prove Prokhorov’s theorem. We also apply the Lévy-Prokhorov metric to show that the measurable space of finite measures on a standard Borel space is again a standard Borel space.

Cite as

Michikazu Hirata. A Formalization of the Lévy-Prokhorov Metric in Isabelle/HOL. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 21:1-21:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{hirata:LIPIcs.ITP.2024.21,
  author =	{Hirata, Michikazu},
  title =	{{A Formalization of the L\'{e}vy-Prokhorov Metric in Isabelle/HOL}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{21:1--21:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-337-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{309},
  editor =	{Bertot, Yves and Kutsia, Temur and Norrish, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2024.21},
  URN =		{urn:nbn:de:0030-drops-207492},
  doi =		{10.4230/LIPIcs.ITP.2024.21},
  annote =	{Keywords: formalization of mathematics, measure theory, metric spaces, topology, L\'{e}vy-Prokhorov metric, Prokhorov’s theorem, Isabelle/HOL}
}
Document
Semantic Foundations of Higher-Order Probabilistic Programs in Isabelle/HOL

Authors: Michikazu Hirata, Yasuhiko Minamide, and Tetsuya Sato

Published in: LIPIcs, Volume 268, 14th International Conference on Interactive Theorem Proving (ITP 2023)


Abstract
Higher-order probabilistic programs are used to describe statistical models and machine-learning mechanisms. The programming languages for them are equipped with three features: higher-order functions, sampling, and conditioning. In this paper, we propose an Isabelle/HOL library for probabilistic programs supporting all of those three features. We extend our previous quasi-Borel theory library in Isabelle/HOL. As a basis of the theory, we formalize s-finite kernels, which is considered as a theoretical foundation of first-order probabilistic programs and a key to support conditioning of probabilistic programs. We also formalize the Borel isomorphism theorem which plays an important role in the quasi-Borel theory. Using them, we develop the s-finite measure monad on quasi-Borel spaces. Our extension enables us to describe higher-order probabilistic programs with conditioning directly as an Isabelle/HOL term whose type is that of morphisms between quasi-Borel spaces. We also implement the qbs prover for checking well-typedness of an Isabelle/HOL term as a morphism between quasi-Borel spaces. We demonstrate several verification examples of higher-order probabilistic programs with conditioning.

Cite as

Michikazu Hirata, Yasuhiko Minamide, and Tetsuya Sato. Semantic Foundations of Higher-Order Probabilistic Programs in Isabelle/HOL. In 14th International Conference on Interactive Theorem Proving (ITP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 268, pp. 18:1-18:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{hirata_et_al:LIPIcs.ITP.2023.18,
  author =	{Hirata, Michikazu and Minamide, Yasuhiko and Sato, Tetsuya},
  title =	{{Semantic Foundations of Higher-Order Probabilistic Programs in Isabelle/HOL}},
  booktitle =	{14th International Conference on Interactive Theorem Proving (ITP 2023)},
  pages =	{18:1--18:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-284-6},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{268},
  editor =	{Naumowicz, Adam and Thiemann, Ren\'{e}},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2023.18},
  URN =		{urn:nbn:de:0030-drops-183933},
  doi =		{10.4230/LIPIcs.ITP.2023.18},
  annote =	{Keywords: Higher-order probabilistic program, s-finite kernel, Quasi-Borel spaces, Isabelle/HOL}
}
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