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Documents authored by Lumsdaine, Peter LeFanu


Found 2 Possible Name Variants:

Lumsdaine, Peter L.

Document
Formalization of Mathematics in Type Theory (Dagstuhl Seminar 18341)

Authors: Andrej Bauer, Martín Escardó, Peter L. Lumsdaine, and Assia Mahboubi

Published in: Dagstuhl Reports, Volume 8, Issue 8 (2019)


Abstract
Formalized mathematics is mathematical knowledge (definitions, theorems, and proofs) represented in digital form suitable for computer processing. The central goal of this seminar was to identify the theoretical advances and practical improvements needed in the area of formalized mathematics, in order to make it a mature technology, truly useful to a larger community of students and researchers in mathematics. During the seminar, various software systems for formalization were compared, and potential improvements to existing systems were investigated. There have also been discussions on the representation of algebraic structures in formalization systems.

Cite as

Andrej Bauer, Martín Escardó, Peter L. Lumsdaine, and Assia Mahboubi. Formalization of Mathematics in Type Theory (Dagstuhl Seminar 18341). In Dagstuhl Reports, Volume 8, Issue 8, pp. 130-145, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@Article{bauer_et_al:DagRep.8.8.130,
  author =	{Bauer, Andrej and Escard\'{o}, Mart{\'\i}n and Lumsdaine, Peter L. and Mahboubi, Assia},
  title =	{{Formalization of Mathematics in Type Theory (Dagstuhl Seminar 18341)}},
  pages =	{130--145},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2019},
  volume =	{8},
  number =	{8},
  editor =	{Bauer, Andrej and Escard\'{o}, Mart{\'\i}n and Lumsdaine, Peter L. and Mahboubi, Assia},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.8.8.130},
  URN =		{urn:nbn:de:0030-drops-102370},
  doi =		{10.4230/DagRep.8.8.130},
  annote =	{Keywords: formal methods, formalized mathematics, proof assistant, type theory}
}

Lumsdaine, Peter LeFanu

Document
Parametricity, Automorphisms of the Universe, and Excluded Middle

Authors: Auke B. Booij, Martín H. Escardó, Peter LeFanu Lumsdaine, and Michael Shulman

Published in: LIPIcs, Volume 97, 22nd International Conference on Types for Proofs and Programs (TYPES 2016)


Abstract
It is known that one can construct non-parametric functions by assuming classical axioms. Our work is a converse to that: we prove classical axioms in dependent type theory assuming specific instances of non-parametricity. We also address the interaction between classical axioms and the existence of automorphisms of a type universe. We work over intensional Martin-Löf dependent type theory, and for some results assume further principles including function extensionality, propositional extensionality, propositional truncation, and the univalence axiom.

Cite as

Auke B. Booij, Martín H. Escardó, Peter LeFanu Lumsdaine, and Michael Shulman. Parametricity, Automorphisms of the Universe, and Excluded Middle. In 22nd International Conference on Types for Proofs and Programs (TYPES 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 97, pp. 7:1-7:14, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{booij_et_al:LIPIcs.TYPES.2016.7,
  author =	{Booij, Auke B. and Escard\'{o}, Mart{\'\i}n H. and Lumsdaine, Peter LeFanu and Shulman, Michael},
  title =	{{Parametricity, Automorphisms of the Universe, and Excluded Middle}},
  booktitle =	{22nd International Conference on Types for Proofs and Programs (TYPES 2016)},
  pages =	{7:1--7:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-065-1},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{97},
  editor =	{Ghilezan, Silvia and Geuvers, Herman and Ivetic, Jelena},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TYPES.2016.7},
  URN =		{urn:nbn:de:0030-drops-98554},
  doi =		{10.4230/LIPIcs.TYPES.2016.7},
  annote =	{Keywords: relational parametricity, dependent type theory, univalent foundations, homotopy type theory, excluded middle, classical mathematics, constructive mat}
}
Document
Displayed Categories

Authors: Benedikt Ahrens and Peter LeFanu Lumsdaine

Published in: LIPIcs, Volume 84, 2nd International Conference on Formal Structures for Computation and Deduction (FSCD 2017)


Abstract
We introduce and develop the notion of displayed categories. A displayed category over a category C is equivalent to "a category D and functor F : D -> C", but instead of having a single collection of "objects of D" with a map to the objects of C, the objects are given as a family indexed by objects of C, and similarly for the morphisms. This encapsulates a common way of building categories in practice, by starting with an existing category and adding extra data/properties to the objects and morphisms. The interest of this seemingly trivial reformulation is that various properties of functors are more naturally defined as properties of the corresponding displayed categories. Grothendieck fibrations, for example, when defined as certain functors, use equality on objects in their definition. When defined instead as certain displayed categories, no reference to equality on objects is required. Moreover, almost all examples of fibrations in nature are, in fact, categories whose standard construction can be seen as going via displayed categories. We therefore propose displayed categories as a basis for the development of fibrations in the type-theoretic setting, and similarly for various other notions whose classical definitions involve equality on objects. Besides giving a conceptual clarification of such issues, displayed categories also provide a powerful tool in computer formalisation, unifying and abstracting common constructions and proof techniques of category theory, and enabling modular reasoning about categories of multi-component structures. As such, most of the material of this article has been formalised in Coq over the UniMath library, with the aim of providing a practical library for use in further developments.

Cite as

Benedikt Ahrens and Peter LeFanu Lumsdaine. Displayed Categories. In 2nd International Conference on Formal Structures for Computation and Deduction (FSCD 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 84, pp. 5:1-5:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2017)


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@InProceedings{ahrens_et_al:LIPIcs.FSCD.2017.5,
  author =	{Ahrens, Benedikt and Lumsdaine, Peter LeFanu},
  title =	{{Displayed Categories}},
  booktitle =	{2nd International Conference on Formal Structures for Computation and Deduction (FSCD 2017)},
  pages =	{5:1--5:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-047-7},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{84},
  editor =	{Miller, Dale},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2017.5},
  URN =		{urn:nbn:de:0030-drops-77220},
  doi =		{10.4230/LIPIcs.FSCD.2017.5},
  annote =	{Keywords: Category theory, Dependent type theory, Computer proof assistants, Coq, Univalent mathematics}
}
Document
Categorical Structures for Type Theory in Univalent Foundations

Authors: Benedikt Ahrens, Peter LeFanu Lumsdaine, and Vladimir Voevodsky

Published in: LIPIcs, Volume 82, 26th EACSL Annual Conference on Computer Science Logic (CSL 2017)


Abstract
In this paper, we analyze and compare three of the many algebraic structures that have been used for modeling dependent type theories: categories with families, split type-categories, and representable maps of presheaves. We study these in the setting of univalent foundations, where the relationships between them can be stated more transparently. Specifically, we construct maps between the different structures and show that these maps are equivalences under suitable assumptions. We then analyze how these structures transfer along (weak and strong) equivalences of categories, and, in particular, show how they descend from a category (not assumed univalent/saturated) to its Rezk completion. To this end, we introduce relative universes, generalizing the preceding notions, and study the transfer of such relative universes along suitable structure. We work throughout in (intensional) dependent type theory; some results, but not all, assume the univalence axiom. All the material of this paper has been formalized in Coq, over the UniMath library.

Cite as

Benedikt Ahrens, Peter LeFanu Lumsdaine, and Vladimir Voevodsky. Categorical Structures for Type Theory in Univalent Foundations. In 26th EACSL Annual Conference on Computer Science Logic (CSL 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 82, pp. 8:1-8:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2017)


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@InProceedings{ahrens_et_al:LIPIcs.CSL.2017.8,
  author =	{Ahrens, Benedikt and Lumsdaine, Peter LeFanu and Voevodsky, Vladimir},
  title =	{{Categorical Structures for Type Theory in Univalent Foundations}},
  booktitle =	{26th EACSL Annual Conference on Computer Science Logic (CSL 2017)},
  pages =	{8:1--8:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-045-3},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{82},
  editor =	{Goranko, Valentin and Dam, Mads},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2017.8},
  URN =		{urn:nbn:de:0030-drops-76960},
  doi =		{10.4230/LIPIcs.CSL.2017.8},
  annote =	{Keywords: Categorical Semantics, Type Theory, Univalence Axiom}
}
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