5 Search Results for "Magaud, Nicolas"

Document
DOI: 10.4230/LIPIcs.ITP.2025.2
A Formal Analysis of Algorithms for Matroids and Greedoids

Authors: Mohammad Abdulaziz, Thomas Ammer, Shriya Meenakshisundaram, and Adem Rimpapa

Published in: LIPIcs, Volume 352, 16th International Conference on Interactive Theorem Proving (ITP 2025)

Abstract
We present a formal analysis, in Isabelle/HOL, of optimisation algorithms for matroids, which are useful generalisations of combinatorial structures that occur in optimisation, and greedoids, which are a generalisation of matroids. Although some formalisation work has been done earlier on matroids, our work here presents the first formalisation of results on greedoids, and many results we formalise in relation to matroids are also formalised for the first time in this work. We formalise the analysis of a number of optimisation algorithms for matroids and greedoids. We also derive from those algorithms executable implementations of Kruskal’s algorithm for computing optimal spanning trees, an algorithm for maximum cardinality matching for bi-partite graphs, and Prim’s algorithm for computing minimum weight spanning trees.
Cite as

Mohammad Abdulaziz, Thomas Ammer, Shriya Meenakshisundaram, and Adem Rimpapa. A Formal Analysis of Algorithms for Matroids and Greedoids. In 16th International Conference on Interactive Theorem Proving (ITP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 352, pp. 2:1-2:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{abdulaziz_et_al:LIPIcs.ITP.2025.2,
  author =	{Abdulaziz, Mohammad and Ammer, Thomas and Meenakshisundaram, Shriya and Rimpapa, Adem},
  title =	{{A Formal Analysis of Algorithms for Matroids and Greedoids}},
  booktitle =	{16th International Conference on Interactive Theorem Proving (ITP 2025)},
  pages =	{2:1--2:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-396-6},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{352},
  editor =	{Forster, Yannick and Keller, Chantal},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2025.2},
  URN =		{urn:nbn:de:0030-drops-246012},
  doi =		{10.4230/LIPIcs.ITP.2025.2},
  annote =	{Keywords: Matroids, Greedoids, Combinatorial Optimisation, Graph Algorithms, Isabelle/HOL, Formal Verification}
}
Document
DOI: 10.4230/LIPIcs.ITP.2025.24
Formally Verifying a Vertical Cell Decomposition Algorithm

Authors: Yves Bertot and Thomas Portet

Published in: LIPIcs, Volume 352, 16th International Conference on Interactive Theorem Proving (ITP 2025)

Abstract
The broad context of this work is the application of formal methods to geometry and robotics. We describe an algorithm to decompose a working area containing obstacles into a collection of safe cells and the formal proof that this algorithm is correct. We expect such an algorithm will be useful to compute safe trajectories. To our knowledge, this is one of the first formalization of such an algorithm to decompose a working space into elementary cells that are suitable for later applications, with the proof of correctness that guarantees that large parts of the working space are safe. Techniques to perform this proof go from algebraic reasoning on coordinates and determinants to sorting. The main difficulty comes from the possible existence of degenerate cases, which are treated in a principled way.
Cite as

Yves Bertot and Thomas Portet. Formally Verifying a Vertical Cell Decomposition Algorithm. In 16th International Conference on Interactive Theorem Proving (ITP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 352, pp. 24:1-24:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{bertot_et_al:LIPIcs.ITP.2025.24,
  author =	{Bertot, Yves and Portet, Thomas},
  title =	{{Formally Verifying a Vertical Cell Decomposition Algorithm}},
  booktitle =	{16th International Conference on Interactive Theorem Proving (ITP 2025)},
  pages =	{24:1--24:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-396-6},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{352},
  editor =	{Forster, Yannick and Keller, Chantal},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2025.24},
  URN =		{urn:nbn:de:0030-drops-246222},
  doi =		{10.4230/LIPIcs.ITP.2025.24},
  annote =	{Keywords: Formal Verification, Motion planning, algorithmic geometry}
}
Document
DOI: 10.4230/LIPIcs.ITP.2025.12
Automatically Generalizing Proofs and Statements

Authors: Anshula Gandhi, Anand Rao Tadipatri, and Timothy Gowers

Published in: LIPIcs, Volume 352, 16th International Conference on Interactive Theorem Proving (ITP 2025)

Abstract
We present an algorithm, developed in the Lean programming language, to automatically generalize mathematical proofs. The algorithm, which builds on work by Olivier Pons, advances state-of-the-art proof generalization by robustly generalizing repeated and related constants, as well as abstracting out hypotheses implicitly concerning them. We also discuss the role of proof generalization in conjecturing, learning from failure, and other aspects of mathematical proof discovery.
Cite as

Anshula Gandhi, Anand Rao Tadipatri, and Timothy Gowers. Automatically Generalizing Proofs and Statements. In 16th International Conference on Interactive Theorem Proving (ITP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 352, pp. 12:1-12:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{gandhi_et_al:LIPIcs.ITP.2025.12,
  author =	{Gandhi, Anshula and Tadipatri, Anand Rao and Gowers, Timothy},
  title =	{{Automatically Generalizing Proofs and Statements}},
  booktitle =	{16th International Conference on Interactive Theorem Proving (ITP 2025)},
  pages =	{12:1--12:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-396-6},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{352},
  editor =	{Forster, Yannick and Keller, Chantal},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2025.12},
  URN =		{urn:nbn:de:0030-drops-246104},
  doi =		{10.4230/LIPIcs.ITP.2025.12},
  annote =	{Keywords: automated reasoning, automated theorem proving, interactive theorem proving, formalization of mathematics, generalization, Lean theorem prover, Lean tactic}
}
Document
DOI: 10.4230/LIPIcs.TYPES.2022.11
Pragmatic Isomorphism Proofs Between Coq Representations: Application to Lambda-Term Families

Authors: Catherine Dubois, Nicolas Magaud, and Alain Giorgetti

Published in: LIPIcs, Volume 269, 28th International Conference on Types for Proofs and Programs (TYPES 2022)

Abstract
There are several ways to formally represent families of data, such as lambda terms, in a type theory such as the dependent type theory of Coq. Mathematical representations are very compact ones and usually rely on the use of dependent types, but they tend to be difficult to handle in practice. On the contrary, implementations based on a larger (and simpler) data structure combined with a restriction property are much easier to deal with. In this work, we study several families related to lambda terms, among which Motzkin trees, seen as lambda term skeletons, closable Motzkin trees, corresponding to closed lambda terms, and a parameterized family of open lambda terms. For each of these families, we define two different representations, show that they are isomorphic and provide tools to switch from one representation to another. All these datatypes and their associated transformations are implemented in the Coq proof assistant. Furthermore we implement random generators for each representation, using the QuickChick plugin.
Cite as

Catherine Dubois, Nicolas Magaud, and Alain Giorgetti. Pragmatic Isomorphism Proofs Between Coq Representations: Application to Lambda-Term Families. In 28th International Conference on Types for Proofs and Programs (TYPES 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 269, pp. 11:1-11:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{dubois_et_al:LIPIcs.TYPES.2022.11,
  author =	{Dubois, Catherine and Magaud, Nicolas and Giorgetti, Alain},
  title =	{{Pragmatic Isomorphism Proofs Between Coq Representations: Application to Lambda-Term Families}},
  booktitle =	{28th International Conference on Types for Proofs and Programs (TYPES 2022)},
  pages =	{11:1--11:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-285-3},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{269},
  editor =	{Kesner, Delia and P\'{e}drot, Pierre-Marie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TYPES.2022.11},
  URN =		{urn:nbn:de:0030-drops-184548},
  doi =		{10.4230/LIPIcs.TYPES.2022.11},
  annote =	{Keywords: Data Representations, Isomorphisms, dependent Types, formal Proofs, random Generation, lambda Terms, Coq}
}
Document
DOI: 10.4230/LIPIcs.ITP.2022.25
Proof Pearl: Formalizing Spreads and Packings of the Smallest Projective Space PG(3,2) Using the Coq Proof Assistant

Authors: Nicolas Magaud

Published in: LIPIcs, Volume 237, 13th International Conference on Interactive Theorem Proving (ITP 2022)

Abstract
We formally implement the smallest three-dimensional projective space PG(3,2) in the Coq proof assistant. This projective space features 15 points and 35 lines, related by an incidence relation. We define points and lines as two plain datatypes (one with 15 constructors for points, and one with 35 constructors for lines) and the incidence relation as a boolean function, instead of using the well-known coordinate-based approach relying on GF(2)⁴. We prove that this implementation actually verifies all the usual properties of three-dimensional projective spaces. We then use an oracle to compute some characteristic subsets of objects of PG(3,2), namely spreads and packings. We formally verify that these computed objects exactly correspond to the spreads and packings of PG(3,2). For spreads, this means identifying 56 specific sets of 5 lines among 360 360 (= 15× 14× 13× 12× 11) possible ones. We then classify them, showing that the 56 spreads of PG(3,2) are all isomorphic whereas the 240 packings of PG(3,2) can be classified into two distinct classes of 120 elements. Proving these results requires partially automating the generation of some large specification files as well as some even larger proof scripts. Overall, this work can be viewed as an example of a large-scale combination of interactive and automated specifications and proofs. It is also a first step towards formalizing projective spaces of higher dimension, e.g. PG(4,2), or larger order, e.g. PG(3,3).
Cite as

Nicolas Magaud. Proof Pearl: Formalizing Spreads and Packings of the Smallest Projective Space PG(3,2) Using the Coq Proof Assistant. In 13th International Conference on Interactive Theorem Proving (ITP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 237, pp. 25:1-25:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{magaud:LIPIcs.ITP.2022.25,
  author =	{Magaud, Nicolas},
  title =	{{Proof Pearl: Formalizing Spreads and Packings of the Smallest Projective Space PG(3,2) Using the Coq Proof Assistant}},
  booktitle =	{13th International Conference on Interactive Theorem Proving (ITP 2022)},
  pages =	{25:1--25:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-252-5},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{237},
  editor =	{Andronick, June and de Moura, Leonardo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2022.25},
  URN =		{urn:nbn:de:0030-drops-167349},
  doi =		{10.4230/LIPIcs.ITP.2022.25},
  annote =	{Keywords: Coq, projective geometry, finite models, spreads, packings, PG(3, 2)}
}
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