24 Search Results for "Nipkow, Tobias"

Document
DOI: 10.4230/LIPIcs.ITP.2024.23
A Generalised Union of Rely-Guarantee and Separation Logic Using Permission Algebras

Authors: Vincent Jackson, Toby Murray, and Christine Rizkallah

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

Abstract
This paper describes GenRGSep, an Isabelle/HOL library for the development of RGSep logics using a general algebraic state model. In particular, we develop an algebraic state models based on resource algebras that assume neither the presence of unit resources or the cancellativity law. If a new resource model is required, its components need only be proven an instance of a permission algebra, and then they can be composed together using tuples and functions. The proof of soundness is performed by Vafeiadis' operational soundness method. This method was originally formulated with respect to a concrete heap model. This paper adapts it to account for the absence of both units as well as the cancellativity law.
Cite as

Vincent Jackson, Toby Murray, and Christine Rizkallah. A Generalised Union of Rely-Guarantee and Separation Logic Using Permission Algebras. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 23:1-23:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{jackson_et_al:LIPIcs.ITP.2024.23,
  author =	{Jackson, Vincent and Murray, Toby and Rizkallah, Christine},
  title =	{{A Generalised Union of Rely-Guarantee and Separation Logic Using Permission Algebras}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{23:1--23:16},
  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.2024.23},
  URN =		{urn:nbn:de:0030-drops-207510},
  doi =		{10.4230/LIPIcs.ITP.2024.23},
  annote =	{Keywords: verification, concurrency, rely-guarantee, separation logic, resource algebras}
}
Document
DOI: 10.4230/LIPIcs.ITP.2024.18
Mechanized HOL Reasoning in Set Theory

Authors: Simon Guilloud, Sankalp Gambhir, Andrea Gilot, and Viktor Kunčak

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

Abstract
We present a mechanized embedding of higher-order logic (HOL) and algebraic data types (ADTs) into first-order logic with ZFC axioms. Our approach interprets types as sets, with function (arrow) types coinciding with set-theoretic function spaces. We assume traditional FOL syntax without notation for term-level binders. To embed λ-terms, we define a notion of context, defining the closure of all abstractions occuring inside a term. We implement the embedding in the Lisa proof assistant for schematic first-order logic and its library based on axiomatic set theory (presented at ITP 2023). We show how to implement type checking and the proof steps of HOL Light as proof-producing tactics in Lisa. The embedded HOL theorems and proofs are interoperable with the existing Lisa library. This yields a form of soft type system supporting top-level polymorphism and ADTs within set theory. The approach offers tools for Lisa users to carry HOL-style proofs within set theory. It also enables the import of HOL Light theorem statements into Lisa, as well as the replay of small HOL Light kernel proofs.
Cite as

Simon Guilloud, Sankalp Gambhir, Andrea Gilot, and Viktor Kunčak. Mechanized HOL Reasoning in Set Theory. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 18:1-18:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{guilloud_et_al:LIPIcs.ITP.2024.18,
  author =	{Guilloud, Simon and Gambhir, Sankalp and Gilot, Andrea and Kun\v{c}ak, Viktor},
  title =	{{Mechanized HOL Reasoning in Set Theory}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{18:1--18:18},
  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.2024.18},
  URN =		{urn:nbn:de:0030-drops-207464},
  doi =		{10.4230/LIPIcs.ITP.2024.18},
  annote =	{Keywords: Proof assistant, First Order Logic, Set Theory, Higher Order Logic}
}
Document
DOI: 10.4230/LIPIcs.ITP.2024.12
A Modular Formalization of Superposition in Isabelle/HOL

Authors: Martin Desharnais, Balazs Toth, Uwe Waldmann, Jasmin Blanchette, and Sophie Tourret

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

Abstract
Superposition is an efficient proof calculus for reasoning about first-order logic with equality that is implemented in many automatic theorem provers. It works by saturating the given set of clauses and is refutationally complete, meaning that if the set is inconsistent, the saturation will contain a contradiction. In this work, we restructured the completeness proof to cleanly separate the ground (i.e., variable-free) and nonground aspects, and we formalized the result in Isabelle/HOL. We relied on the IsaFoR library for first-order terms and on the Isabelle saturation framework.
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Martin Desharnais, Balazs Toth, Uwe Waldmann, Jasmin Blanchette, and Sophie Tourret. A Modular Formalization of Superposition in Isabelle/HOL. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 12:1-12:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{desharnais_et_al:LIPIcs.ITP.2024.12,
  author =	{Desharnais, Martin and Toth, Balazs and Waldmann, Uwe and Blanchette, Jasmin and Tourret, Sophie},
  title =	{{A Modular Formalization of Superposition in Isabelle/HOL}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{12:1--12:20},
  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.2024.12},
  URN =		{urn:nbn:de:0030-drops-207401},
  doi =		{10.4230/LIPIcs.ITP.2024.12},
  annote =	{Keywords: Superposition, verification, first-order logic, higher-order logic}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ITP.2024.1
Alpha-Beta Pruning Verified (Invited Talk)

Authors: Tobias Nipkow

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

Abstract
Alpha-beta pruning is an efficient search strategy for two-player game trees. It was invented in the late 1950s and is at the heart of most implementations of combinatorial game playing programs. We have formalized and verified a number of variations of alpha-beta pruning, in particular fail-hard and fail-soft, and valuations into linear orders, distributive lattices and domains with negative values.
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Tobias Nipkow. Alpha-Beta Pruning Verified (Invited Talk). In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 1:1-1:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{nipkow:LIPIcs.ITP.2024.1,
  author =	{Nipkow, Tobias},
  title =	{{Alpha-Beta Pruning Verified}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{1:1--1:4},
  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.2024.1},
  URN =		{urn:nbn:de:0030-drops-207294},
  doi =		{10.4230/LIPIcs.ITP.2024.1},
  annote =	{Keywords: Verification, Algorithmic Game Theory, Isabelle}
}
Document
DOI: 10.4230/LIPIcs.ITP.2024.31
A Verified Earley Parser

Authors: Martin Rau and Tobias Nipkow

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

Abstract
An Earley parser is a top-down parsing technique that is capable of parsing arbitrary context-free grammars. We present a functional implementation of an Earley parser verified using the interactive theorem prover Isabelle/HOL. Our formalization builds upon Cliff Jones' extensive, refinement-based paper proof. We implement and prove soundness and completeness of a functional recognizer modeling Jay Earley’s original imperative implementation and extend it with the necessary data structures to enable the construction of parse trees following the work of Elizabeth Scott. Building upon this foundation, we develop a functional parser and prove its soundness. We round off the paper by providing an informal argument and empirical data regarding the running time and space complexity of our implementation.
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Martin Rau and Tobias Nipkow. A Verified Earley Parser. In 15th International Conference on Interactive Theorem Proving (ITP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 309, pp. 31:1-31:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{rau_et_al:LIPIcs.ITP.2024.31,
  author =	{Rau, Martin and Nipkow, Tobias},
  title =	{{A Verified Earley Parser}},
  booktitle =	{15th International Conference on Interactive Theorem Proving (ITP 2024)},
  pages =	{31:1--31:18},
  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.2024.31},
  URN =		{urn:nbn:de:0030-drops-207596},
  doi =		{10.4230/LIPIcs.ITP.2024.31},
  annote =	{Keywords: Verification, Parsers, Earley, Isabelle}
}
Document
Track B: Automata, Logic, Semantics, and Theory of Programming
DOI: 10.4230/LIPIcs.ICALP.2024.139
T-Rex: Termination of Recursive Functions Using Lexicographic Linear Combinations

Authors: Raphael Douglas Giles, Vincent Jackson, and Christine Rizkallah

Published in: LIPIcs, Volume 297, 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)

Abstract
We introduce a powerful termination algorithm for structurally recursive functions that improves on the core ideas behind lexicographic termination algorithms for functional programs. The algorithm generates linear-lexicographic combinations of primitive measure functions measuring the recursive structure of terms. We introduce a measure language that enables the simplification and comparison of measures and we prove meta-theoretic properties of our measure language. Moreover, we demonstrate our algorithm, on an untyped first-order functional language and prove its soundness and that it runs in polynomial time. We also provide a Haskell implementation. As part of this work, we also show how to solve the maximisation of negative vector-components as a linear program.
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Raphael Douglas Giles, Vincent Jackson, and Christine Rizkallah. T-Rex: Termination of Recursive Functions Using Lexicographic Linear Combinations. In 51st International Colloquium on Automata, Languages, and Programming (ICALP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 297, pp. 139:1-139:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{giles_et_al:LIPIcs.ICALP.2024.139,
  author =	{Giles, Raphael Douglas and Jackson, Vincent and Rizkallah, Christine},
  title =	{{T-Rex: Termination of Recursive Functions Using Lexicographic Linear Combinations}},
  booktitle =	{51st International Colloquium on Automata, Languages, and Programming (ICALP 2024)},
  pages =	{139:1--139:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-322-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{297},
  editor =	{Bringmann, Karl and Grohe, Martin and Puppis, Gabriele and Svensson, Ola},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2024.139},
  URN =		{urn:nbn:de:0030-drops-202827},
  doi =		{10.4230/LIPIcs.ICALP.2024.139},
  annote =	{Keywords: Termination, Recursive functions}
}
Document
DOI: 10.4230/OASIcs.FMBC.2024.2
Formal Specification of the Cardano Blockchain Ledger, Mechanized in Agda

Authors: Andre Knispel, Orestis Melkonian, James Chapman, Alasdair Hill, Joosep Jääger, William DeMeo, and Ulf Norell

Published in: OASIcs, Volume 118, 5th International Workshop on Formal Methods for Blockchains (FMBC 2024)

Abstract
Blockchain systems comprise critical software that handle substantial monetary funds, rendering them excellent candidates for formal verification. One of their core components is the underlying ledger that does all the accounting: keeping track of transactions and their validity, etc. Unfortunately, previous theoretical studies are typically confined to an idealized setting, while specifications for real implementations are scarce; either the functionality is directly implemented without a proper specification, or at best an informal specification is written on paper. The present work expands beyond prior meta-theoretical investigations of the EUTxO model to encompass the full scale of the Cardano blockchain: our formal specification describes a hierarchy of modular transitions that covers all the intricacies of a realistic blockchain, such as fully expressive smart contracts and decentralized governance. It is mechanized in a proof assistant, thus enjoys a higher standard of rigor: type-checking prevents minor oversights that were frequent in previous informal approaches; key meta-theoretical properties can now be formally proven; it is an executable specification against which the implementation in production is being tested for conformance; and it provides firm foundations for smart contract verification. Apart from a safety net to keep us in check, the formalization also provides a guideline for the ledger design: one informs the other in a symbiotic way, especially in the case of state-of-the-art features like decentralized governance, which is an emerging sub-field of blockchain research that however mandates a more exploratory approach. All the results presented in this paper have been mechanized in the Agda proof assistant and are publicly available. In fact, this document is itself a literate Agda script and all rendered code has been successfully type-checked.
Cite as

Andre Knispel, Orestis Melkonian, James Chapman, Alasdair Hill, Joosep Jääger, William DeMeo, and Ulf Norell. Formal Specification of the Cardano Blockchain Ledger, Mechanized in Agda. In 5th International Workshop on Formal Methods for Blockchains (FMBC 2024). Open Access Series in Informatics (OASIcs), Volume 118, pp. 2:1-2:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{knispel_et_al:OASIcs.FMBC.2024.2,
  author =	{Knispel, Andre and Melkonian, Orestis and Chapman, James and Hill, Alasdair and J\"{a}\"{a}ger, Joosep and DeMeo, William and Norell, Ulf},
  title =	{{Formal Specification of the Cardano Blockchain Ledger, Mechanized in Agda}},
  booktitle =	{5th International Workshop on Formal Methods for Blockchains (FMBC 2024)},
  pages =	{2:1--2:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-317-1},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{118},
  editor =	{Bernardo, Bruno and Marmsoler, Diego},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FMBC.2024.2},
  URN =		{urn:nbn:de:0030-drops-198673},
  doi =		{10.4230/OASIcs.FMBC.2024.2},
  annote =	{Keywords: blockchain, distributed ledgers, UTxO, Cardano, formal verification, Agda}
}
Document
RANDOM
DOI: 10.4230/LIPIcs.APPROX/RANDOM.2023.35
An Embarrassingly Parallel Optimal-Space Cardinality Estimation Algorithm

Authors: Emin Karayel

Published in: LIPIcs, Volume 275, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2023)

Abstract
In 2020 Błasiok (ACM Trans. Algorithms 16(2) 3:1-3:28) constructed an optimal space streaming algorithm for the cardinality estimation problem with the space complexity of O(ε^{-2} ln(δ^{-1}) + ln n) where ε, δ and n denote the relative accuracy, failure probability and universe size, respectively. However, his solution requires the stream to be processed sequentially. On the other hand, there are algorithms that admit a merge operation; they can be used in a distributed setting, allowing parallel processing of sections of the stream, and are highly relevant for large-scale distributed applications. The best-known such algorithm, unfortunately, has a space complexity exceeding Ω(ln(δ^{-1}) (ε^{-2} ln ln n + ln n)). This work presents a new algorithm that improves on the solution by Błasiok, preserving its space complexity, but with the benefit that it admits such a merge operation, thus providing an optimal solution for the problem for both sequential and parallel applications. Orthogonally, the new algorithm also improves algorithmically on Błasiok’s solution (even in the sequential setting) by reducing its implementation complexity and requiring fewer distinct pseudo-random objects.
Cite as

Emin Karayel. An Embarrassingly Parallel Optimal-Space Cardinality Estimation Algorithm. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 275, pp. 35:1-35:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{karayel:LIPIcs.APPROX/RANDOM.2023.35,
  author =	{Karayel, Emin},
  title =	{{An Embarrassingly Parallel Optimal-Space Cardinality Estimation Algorithm}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2023)},
  pages =	{35:1--35:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-296-9},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{275},
  editor =	{Megow, Nicole and Smith, Adam},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2023.35},
  URN =		{urn:nbn:de:0030-drops-188607},
  doi =		{10.4230/LIPIcs.APPROX/RANDOM.2023.35},
  annote =	{Keywords: Distinct Elements, Distributed Algorithms, Randomized Algorithms, Expander Graphs, Derandomization, Sketching}
}
Document
DOI: 10.4230/LIPIcs.ITP.2023.4
Fast, Verified Computation for Candle

Authors: Oskar Abrahamsson and Magnus O. Myreen

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

Abstract
This paper describes how we have added an efficient function for computation to the kernel of the Candle interactive theorem prover. Candle is a CakeML port of HOL Light which we have, in prior work, proved sound w.r.t. the inference rules of the higher-order logic. This paper extends the original implementation and soundness proof with a new kernel function for fast computation. Experiments show that the new computation function is able to speed up certain evaluation proofs by several orders of magnitude.
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Oskar Abrahamsson and Magnus O. Myreen. Fast, Verified Computation for Candle. In 14th International Conference on Interactive Theorem Proving (ITP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 268, pp. 4:1-4:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{abrahamsson_et_al:LIPIcs.ITP.2023.4,
  author =	{Abrahamsson, Oskar and Myreen, Magnus O.},
  title =	{{Fast, Verified Computation for Candle}},
  booktitle =	{14th International Conference on Interactive Theorem Proving (ITP 2023)},
  pages =	{4:1--4:17},
  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.2023.4},
  URN =		{urn:nbn:de:0030-drops-183797},
  doi =		{10.4230/LIPIcs.ITP.2023.4},
  annote =	{Keywords: Prover soundness, Higher-order logic, Interactive theorem proving}
}
Document
DOI: 10.4230/LIPIcs.ITP.2023.29
Real-Time Double-Ended Queue Verified (Proof Pearl)

Authors: Balazs Toth and Tobias Nipkow

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

Abstract
We present the first verification of the real-time doubled-ended queue by Chuang and Goldberg where all operations take constant time. The main contributions are the full system invariant, the precise definition of all abstraction functions, the structure of the proof and the main lemmas.
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Balazs Toth and Tobias Nipkow. Real-Time Double-Ended Queue Verified (Proof Pearl). In 14th International Conference on Interactive Theorem Proving (ITP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 268, pp. 29:1-29:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{toth_et_al:LIPIcs.ITP.2023.29,
  author =	{Toth, Balazs and Nipkow, Tobias},
  title =	{{Real-Time Double-Ended Queue Verified (Proof Pearl)}},
  booktitle =	{14th International Conference on Interactive Theorem Proving (ITP 2023)},
  pages =	{29:1--29:18},
  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.2023.29},
  URN =		{urn:nbn:de:0030-drops-184044},
  doi =		{10.4230/LIPIcs.ITP.2023.29},
  annote =	{Keywords: Double-ended queue, data structures, verification, Isabelle}
}
Document
DOI: 10.4230/LIPIcs.ITP.2022.21
Formalization of Randomized Approximation Algorithms for Frequency Moments

Authors: Emin Karayel

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

Abstract
In 1999 Alon et al. introduced the still active research topic of approximating the frequency moments of a data stream using randomized algorithms with minimal space usage. This includes the problem of estimating the cardinality of the stream elements - the zeroth frequency moment. Higher-order frequency moments provide information about the skew of the data stream which is, for example, critical information for parallel processing. (The k-th frequency moment of a data stream is the sum of the k-th powers of the occurrence counts of each element in the stream.) They introduce both lower bounds and upper bounds on the space complexity of the problems, which were later improved by newer publications. The algorithms have guaranteed success probabilities and accuracies without making any assumptions on the input distribution. They are an interesting use case for formal verification because their correctness proofs require a large body of deep results from algebra, analysis and probability theory. This work reports on the formal verification of three algorithms for the approximation of F₀, F₂ and F_k for k ≥ 3. The results include the identification of significantly simpler algorithms with the same runtime and space complexities as the previously known ones as well as the development of several reusable components, such as a formalization of universal hash families, amplification methods for randomized algorithms, a model for one-pass data stream algorithms or a generic flexible encoding library for the verification of space complexities.
Cite as

Emin Karayel. Formalization of Randomized Approximation Algorithms for Frequency Moments. In 13th International Conference on Interactive Theorem Proving (ITP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 237, pp. 21:1-21:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{karayel:LIPIcs.ITP.2022.21,
  author =	{Karayel, Emin},
  title =	{{Formalization of Randomized Approximation Algorithms for Frequency Moments}},
  booktitle =	{13th International Conference on Interactive Theorem Proving (ITP 2022)},
  pages =	{21:1--21:21},
  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.2022.21},
  URN =		{urn:nbn:de:0030-drops-167308},
  doi =		{10.4230/LIPIcs.ITP.2022.21},
  annote =	{Keywords: Formal Verification, Isabelle/HOL, Randomized Algorithms, Frequency Moments}
}
Document
DOI: 10.4230/LIPIcs.ITP.2019.11
A Verified and Compositional Translation of LTL to Deterministic Rabin Automata

Authors: Julian Brunner, Benedikt Seidl, and Salomon Sickert

Published in: LIPIcs, Volume 141, 10th International Conference on Interactive Theorem Proving (ITP 2019)

Abstract
We present a formalisation of the unified translation approach from linear temporal logic (LTL) to omega-automata from [Javier Esparza et al., 2018]. This approach decomposes LTL formulas into "simple" languages and allows a clear separation of concerns: first, we formalise the purely logical result yielding this decomposition; second, we develop a generic, executable, and expressive automata library providing necessary operations on automata to re-combine the "simple" languages; third, we instantiate this generic theory to obtain a construction for deterministic Rabin automata (DRA). We extract from this particular instantiation an executable tool translating LTL to DRAs. To the best of our knowledge this is the first verified translation of LTL to DRAs that is proven to be double-exponential in the worst case which asymptotically matches the known lower bound.
Cite as

Julian Brunner, Benedikt Seidl, and Salomon Sickert. A Verified and Compositional Translation of LTL to Deterministic Rabin Automata. In 10th International Conference on Interactive Theorem Proving (ITP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 141, pp. 11:1-11:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{brunner_et_al:LIPIcs.ITP.2019.11,
  author =	{Brunner, Julian and Seidl, Benedikt and Sickert, Salomon},
  title =	{{A Verified and Compositional Translation of LTL to Deterministic Rabin Automata}},
  booktitle =	{10th International Conference on Interactive Theorem Proving (ITP 2019)},
  pages =	{11:1--11:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-122-1},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{141},
  editor =	{Harrison, John and O'Leary, John and Tolmach, Andrew},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2019.11},
  URN =		{urn:nbn:de:0030-drops-110664},
  doi =		{10.4230/LIPIcs.ITP.2019.11},
  annote =	{Keywords: Automata Theory, Automata over Infinite Words, Deterministic Automata, Linear Temporal Logic, Model Checking, Verified Algorithms}
}
Document
DOI: 10.4230/LIPIcs.ITP.2019.23
Proof Pearl: Purely Functional, Simple and Efficient Priority Search Trees and Applications to Prim and Dijkstra

Authors: Peter Lammich and Tobias Nipkow

Published in: LIPIcs, Volume 141, 10th International Conference on Interactive Theorem Proving (ITP 2019)

Abstract
The starting point of this paper is a new, purely functional, simple and efficient data structure combining a search tree and a priority queue, which we call a priority search tree. The salient feature of priority search trees is that they offer a decrease-key operation, something that is missing from other simple, purely functional priority queue implementations. As two applications of this data structure we verify purely functional, simple and efficient implementations of Prim’s and Dijkstra’s algorithms. This constitutes the first verification of an executable and even efficient version of Prim’s algorithm.
Cite as

Peter Lammich and Tobias Nipkow. Proof Pearl: Purely Functional, Simple and Efficient Priority Search Trees and Applications to Prim and Dijkstra. In 10th International Conference on Interactive Theorem Proving (ITP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 141, pp. 23:1-23:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{lammich_et_al:LIPIcs.ITP.2019.23,
  author =	{Lammich, Peter and Nipkow, Tobias},
  title =	{{Proof Pearl: Purely Functional, Simple and Efficient Priority Search Trees and Applications to Prim and Dijkstra}},
  booktitle =	{10th International Conference on Interactive Theorem Proving (ITP 2019)},
  pages =	{23:1--23:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-122-1},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{141},
  editor =	{Harrison, John and O'Leary, John and Tolmach, Andrew},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2019.23},
  URN =		{urn:nbn:de:0030-drops-110788},
  doi =		{10.4230/LIPIcs.ITP.2019.23},
  annote =	{Keywords: Priority queue, Dijkstra’s algorithm, Prim’s algorithm, verification, Isabelle}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.MFCS.2019.1
Trustworthy Graph Algorithms (Invited Talk)

Authors: Mohammad Abdulaziz, Kurt Mehlhorn, and Tobias Nipkow

Published in: LIPIcs, Volume 138, 44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)

Abstract
The goal of the LEDA project was to build an easy-to-use and extendable library of correct and efficient data structures, graph algorithms and geometric algorithms. We report on the use of formal program verification to achieve an even higher level of trustworthiness. Specifically, we report on an ongoing and largely finished verification of the blossom-shrinking algorithm for maximum cardinality matching.
Cite as

Mohammad Abdulaziz, Kurt Mehlhorn, and Tobias Nipkow. Trustworthy Graph Algorithms (Invited Talk). In 44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 138, pp. 1:1-1:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{abdulaziz_et_al:LIPIcs.MFCS.2019.1,
  author =	{Abdulaziz, Mohammad and Mehlhorn, Kurt and Nipkow, Tobias},
  title =	{{Trustworthy Graph Algorithms}},
  booktitle =	{44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)},
  pages =	{1:1--1:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-117-7},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{138},
  editor =	{Rossmanith, Peter and Heggernes, Pinar and Katoen, Joost-Pieter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2019.1},
  URN =		{urn:nbn:de:0030-drops-109456},
  doi =		{10.4230/LIPIcs.MFCS.2019.1},
  annote =	{Keywords: graph algorithms, formal correct proofs, Isabelle, LEDA, certifying algorithms}
}
Document
DOI: 10.4230/LIPIcs.TYPES.2017.5
Formalized Proof Systems for Propositional Logic

Authors: Julius Michaelis and Tobias Nipkow

Published in: LIPIcs, Volume 104, 23rd International Conference on Types for Proofs and Programs (TYPES 2017)

Abstract
We have formalized a range of proof systems for classical propositional logic (sequent calculus, natural deduction, Hilbert systems, resolution) in Isabelle/HOL and have proved the most important meta-theoretic results about semantics and proofs: compactness, soundness, completeness, translations between proof systems, cut-elimination, interpolation and model existence.
Cite as

Julius Michaelis and Tobias Nipkow. Formalized Proof Systems for Propositional Logic. In 23rd International Conference on Types for Proofs and Programs (TYPES 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 104, pp. 5:1-5:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{michaelis_et_al:LIPIcs.TYPES.2017.5,
  author =	{Michaelis, Julius and Nipkow, Tobias},
  title =	{{Formalized Proof Systems for Propositional Logic}},
  booktitle =	{23rd International Conference on Types for Proofs and Programs (TYPES 2017)},
  pages =	{5:1--5:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-071-2},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{104},
  editor =	{Abel, Andreas and Nordvall Forsberg, Fredrik and Kaposi, Ambrus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TYPES.2017.5},
  URN =		{urn:nbn:de:0030-drops-100537},
  doi =		{10.4230/LIPIcs.TYPES.2017.5},
  annote =	{Keywords: formalization of logic, proof systems, sequent calculus, natural deduction, resolution}
}
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