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Documents authored by Lammich, Peter

Document
DOI: 10.4230/LIPIcs.ITP.2022.24
Refinement of Parallel Algorithms down to LLVM

Authors: Peter Lammich

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

Abstract
We present a stepwise refinement approach to develop verified parallel algorithms, down to efficient LLVM code. The resulting algorithms' performance is competitive with their counterparts implemented in C/C++. Our approach is backwards compatible with the Isabelle Refinement Framework, such that existing sequential formalizations can easily be adapted or re-used. As case study, we verify a parallel quicksort algorithm, and show that it performs on par with its C++ implementation, and is competitive to state-of-the-art parallel sorting algorithms.
Cite as

Peter Lammich. Refinement of Parallel Algorithms down to LLVM. In 13th International Conference on Interactive Theorem Proving (ITP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 237, pp. 24:1-24:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{lammich:LIPIcs.ITP.2022.24,
  author =	{Lammich, Peter},
  title =	{{Refinement of Parallel Algorithms down to LLVM}},
  booktitle =	{13th International Conference on Interactive Theorem Proving (ITP 2022)},
  pages =	{24:1--24:18},
  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.2022.24},
  URN =		{urn:nbn:de:0030-drops-167333},
  doi =		{10.4230/LIPIcs.ITP.2022.24},
  annote =	{Keywords: Isabelle, Concurrent Separation Logic, Parallel Sorting, LLVM}
}
Document
Invited Paper
DOI: 10.4230/LIPIcs.ITP.2021.3
Bounded-Deducibility Security (Invited Paper)

Authors: Andrei Popescu, Thomas Bauereiss, and Peter Lammich

Published in: LIPIcs, Volume 193, 12th International Conference on Interactive Theorem Proving (ITP 2021)

Abstract
We describe Bounded-Deducibility (BD) security, an expressive framework for the specification and verification of information-flow security. The framework grew by confronting concrete challenges of specifying and verifying fine-grained confidentiality properties in some realistic web-based systems. The concepts and theorems that constitute this framework have an eventful history of such "confrontations", often involving trial and error, which are reported in previous papers. This paper is the first to focus on the framework itself rather than the case studies, gathering in one place all the abstract results about BD security.
Cite as

Andrei Popescu, Thomas Bauereiss, and Peter Lammich. Bounded-Deducibility Security (Invited Paper). In 12th International Conference on Interactive Theorem Proving (ITP 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 193, pp. 3:1-3:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{popescu_et_al:LIPIcs.ITP.2021.3,
  author =	{Popescu, Andrei and Bauereiss, Thomas and Lammich, Peter},
  title =	{{Bounded-Deducibility Security}},
  booktitle =	{12th International Conference on Interactive Theorem Proving (ITP 2021)},
  pages =	{3:1--3:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-188-7},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{193},
  editor =	{Cohen, Liron and Kaliszyk, Cezary},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2021.3},
  URN =		{urn:nbn:de:0030-drops-138982},
  doi =		{10.4230/LIPIcs.ITP.2021.3},
  annote =	{Keywords: Information-flow security, Unwinding proof method, Compositionality, Verification}
}
Document
DOI: 10.4230/LIPIcs.ITP.2019.20
Refinement with Time - Refining the Run-Time of Algorithms in Isabelle/HOL

Authors: Maximilian P. L. Haslbeck and Peter Lammich

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

Abstract
Separation Logic with Time Credits is a well established method to formally verify the correctness and run-time of algorithms, which has been applied to various medium-sized use-cases. Refinement is a technique in program verification that makes software projects of larger scale manageable. Combining these two techniques for the first time, we present a methodology for verifying the functional correctness and the run-time analysis of algorithms in a modular way. We use it to verify Kruskal’s minimum spanning tree algorithm and the Edmonds - Karp algorithm for network flow. An adaptation of the Isabelle Refinement Framework [Lammich and Tuerk, 2012] enables us to specify the functional result and the run-time behaviour of abstract algorithms which can be refined to more concrete algorithms. From these, executable imperative code can be synthesized by an extension of the Sepref tool [Lammich, 2015], preserving correctness and the run-time bounds of the abstract algorithm.
Cite as

Maximilian P. L. Haslbeck and Peter Lammich. Refinement with Time - Refining the Run-Time of Algorithms in Isabelle/HOL. In 10th International Conference on Interactive Theorem Proving (ITP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 141, pp. 20:1-20:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{haslbeck_et_al:LIPIcs.ITP.2019.20,
  author =	{Haslbeck, Maximilian P. L. and Lammich, Peter},
  title =	{{Refinement with Time - Refining the Run-Time of Algorithms in Isabelle/HOL}},
  booktitle =	{10th International Conference on Interactive Theorem Proving (ITP 2019)},
  pages =	{20:1--20:18},
  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.2019.20},
  URN =		{urn:nbn:de:0030-drops-110754},
  doi =		{10.4230/LIPIcs.ITP.2019.20},
  annote =	{Keywords: Isabelle, Time Complexity Analysis, Separation Logic, Program Verification, Refinement, Run Time, Algorithms}
}
Document
DOI: 10.4230/LIPIcs.ITP.2019.22
Generating Verified LLVM from Isabelle/HOL

Authors: Peter Lammich

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

Abstract
We present a framework to generate verified LLVM programs from Isabelle/HOL. It is based on a code generator that generates LLVM text from a simplified fragment of LLVM, shallowly embedded into Isabelle/HOL. On top, we have developed a separation logic, a verification condition generator, and an LLVM backend to the Isabelle Refinement Framework. As case studies, we have produced verified LLVM implementations of binary search and the Knuth-Morris-Pratt string search algorithm. These are one order of magnitude faster than the Standard-ML implementations produced with the original Refinement Framework, and on par with unverified C implementations. Adoption of the original correctness proofs to the new LLVM backend was straightforward. The trusted code base of our approach is the shallow embedding of the LLVM fragment and the code generator, which is a pretty printer combined with some straightforward compilation steps.
Cite as

Peter Lammich. Generating Verified LLVM from Isabelle/HOL. In 10th International Conference on Interactive Theorem Proving (ITP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 141, pp. 22:1-22:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{lammich:LIPIcs.ITP.2019.22,
  author =	{Lammich, Peter},
  title =	{{Generating Verified LLVM from Isabelle/HOL}},
  booktitle =	{10th International Conference on Interactive Theorem Proving (ITP 2019)},
  pages =	{22:1--22:19},
  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.2019.22},
  URN =		{urn:nbn:de:0030-drops-110777},
  doi =		{10.4230/LIPIcs.ITP.2019.22},
  annote =	{Keywords: Isabelle/HOL, LLVM, Separation Logic, Verification Condition Generator, Code Generation}
}
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}
}
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