8 Search Results for "Hamadi, Youssef"

Document
DOI: 10.4230/LIPIcs.ESA.2024.40
Improved Algorithms for Maximum Coverage in Dynamic and Random Order Streams

Authors: Amit Chakrabarti, Andrew McGregor, and Anthony Wirth

Published in: LIPIcs, Volume 308, 32nd Annual European Symposium on Algorithms (ESA 2024)

Abstract
The maximum coverage problem is to select k sets, from a collection of m sets, such that the cardinality of their union, in a universe of size n, is maximized. We consider (1-1/e-ε)-approximation algorithms for this NP-hard problem in three standard data stream models. 1) Dynamic Model. The stream consists of a sequence of sets being inserted and deleted. Our multi-pass algorithm uses ε^{-2} k ⋅ polylog(n,m) space. The best previous result (Assadi and Khanna, SODA 2018) used (n +ε^{-4} k) polylog(n,m) space. While both algorithms use O(ε^{-1} log m) passes, our analysis shows that, when ε ≤ 1/log log m, it is possible to reduce the number of passes by a 1/log log m factor without incurring additional space. 2) Random Order Model. In this model, there are no deletions, and the sets forming the instance are uniformly randomly permuted to form the input stream. We show that a single pass and k polylog(n,m) space suffices for arbitrary small constant ε. The best previous result, by Warneke et al. (ESA 2023), used k² polylog(n,m) space. 3) Insert-Only Model. Lastly, our results, along with numerous previous results, use a sub-sampling technique introduced by McGregor and Vu (ICDT 2017) to sparsify the input instance. We explain how this technique and others used in the paper can be implemented such that the amortized update time of our algorithm is polylogarithmic. This also implies an improvement of the state-of-the-art insert only algorithms in terms of the update time: polylog(m,n) update time suffices, whereas the best previous result by Jaud et al. (SEA 2023) required update time that was linear in k.
Cite as

Amit Chakrabarti, Andrew McGregor, and Anthony Wirth. Improved Algorithms for Maximum Coverage in Dynamic and Random Order Streams. In 32nd Annual European Symposium on Algorithms (ESA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 308, pp. 40:1-40:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{chakrabarti_et_al:LIPIcs.ESA.2024.40,
  author =	{Chakrabarti, Amit and McGregor, Andrew and Wirth, Anthony},
  title =	{{Improved Algorithms for Maximum Coverage in Dynamic and Random Order Streams}},
  booktitle =	{32nd Annual European Symposium on Algorithms (ESA 2024)},
  pages =	{40:1--40:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-338-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{308},
  editor =	{Chan, Timothy and Fischer, Johannes and Iacono, John and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2024.40},
  URN =		{urn:nbn:de:0030-drops-211114},
  doi =		{10.4230/LIPIcs.ESA.2024.40},
  annote =	{Keywords: Data Stream Computation, Maximum Coverage, Submodular Maximization}
}
Document
DOI: 10.4230/LIPIcs.CP.2024.28
CP for Bin Packing with Multi-Core and GPUs

Authors: Fabio Tardivo, Laurent Michel, and Enrico Pontelli

Published in: LIPIcs, Volume 307, 30th International Conference on Principles and Practice of Constraint Programming (CP 2024)

Abstract
The BinPacking constraint models the requirements of many logistics, resource allocation, and production scheduling applications. This paper explores new avenues based on the impressive computational power of modern GPUs to propagate the BinPacking constraint. This work showcases how the perspective of massive parallelization can lead to novel approaches, such as the use of a portfolio of lower bounds, to enhance the pruning of the BinPacking constraints. It delivers insights into the design choices and challenges presented by GPU platform for constraint propagation. The paper evaluates a GPU-accelerated propagator against both sequential and parallel CPU versions, as well as state-of-the-art approaches. Comparisons across various benchmarks from the literature show strong performances with respect to both CPU versions and the standard pruning approach. When compared to techniques based on Linear Programming, our approach proves valuable for large instances or when spending extensive time to obtain the best possible bound is not convenient.
Cite as

Fabio Tardivo, Laurent Michel, and Enrico Pontelli. CP for Bin Packing with Multi-Core and GPUs. In 30th International Conference on Principles and Practice of Constraint Programming (CP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 307, pp. 28:1-28:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{tardivo_et_al:LIPIcs.CP.2024.28,
  author =	{Tardivo, Fabio and Michel, Laurent and Pontelli, Enrico},
  title =	{{CP for Bin Packing with Multi-Core and GPUs}},
  booktitle =	{30th International Conference on Principles and Practice of Constraint Programming (CP 2024)},
  pages =	{28:1--28:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-336-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{307},
  editor =	{Shaw, Paul},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2024.28},
  URN =		{urn:nbn:de:0030-drops-207138},
  doi =		{10.4230/LIPIcs.CP.2024.28},
  annote =	{Keywords: Constraint Propagation, Bin Packing, Parallelism, GPU, Lower Bounds}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.SAT.2024.1
Models and Counter-Models of Quantified Boolean Formulas (Invited Talk)

Authors: Martina Seidl

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Because of the duality of universal and existential quantification, quantified Boolean formulas (QBF), the extension of propositional logic with quantifiers over the Boolean variables, have not only solutions in terms of models for true formulas like in SAT. Also false QBFs have solutions in terms of counter-models. Both models and counter-models can be represented as certain binary trees or as sets of Boolean functions reflecting the dependencies among the variables of a formula. Such solutions encode the answers to application problems for which QBF solvers are employed like the plan for a planning problem or the error trace of a verification problem. Therefore, models and counter-models are at the core of theory and practice of QBF solving. In this invited talk, we survey approaches that deal with models and counter-models of QBFs and identify some open challenges.
Cite as

Martina Seidl. Models and Counter-Models of Quantified Boolean Formulas (Invited Talk). In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 1:1-1:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{seidl:LIPIcs.SAT.2024.1,
  author =	{Seidl, Martina},
  title =	{{Models and Counter-Models of Quantified Boolean Formulas}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{1:1--1:7},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.1},
  URN =		{urn:nbn:de:0030-drops-205238},
  doi =		{10.4230/LIPIcs.SAT.2024.1},
  annote =	{Keywords: Quantified Boolean Formula, Solution Extraction, Solution Counting}
}
Document
DOI: 10.4230/LIPIcs.SAT.2024.11
On the Relative Efficiency of Dynamic and Static Top-Down Compilation to Decision-DNNF

Authors: Alexis de Colnet

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Top-down compilers of CNF formulas to circuits in decision-DNNF (Decomposable Negation Normal Form) have proved to be useful for model counting. These compilers rely on a common set of techniques including DPLL-style exploration of the set of models, caching of residual formulas, and connected components detection. Differences between compilers lie in the variable selection heuristics and in the additional processing techniques they may use. We investigate, from a theoretical perspective, the ability of top-down compilation algorithms to find small decision-DNNF circuits for two different variable selection strategies. Both strategies are guided by a graph of the CNF formula and are inspired by what is done in practice. The first uses a dynamic graph-partitioning approach while the second works with a static tree decomposition. We show that the dynamic approach performs significantly better than the static approach for some formulas, and that the opposite also holds for other formulas. Our lower bounds are proved despite loose settings where the compilation algorithm is only forced to follow its designed variable selection strategy and where everything else, including the many opportunities for tie-breaking, can be handled non-deterministically.
Cite as

Alexis de Colnet. On the Relative Efficiency of Dynamic and Static Top-Down Compilation to Decision-DNNF. In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 11:1-11:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{decolnet:LIPIcs.SAT.2024.11,
  author =	{de Colnet, Alexis},
  title =	{{On the Relative Efficiency of Dynamic and Static Top-Down Compilation to Decision-DNNF}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{11:1--11:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.11},
  URN =		{urn:nbn:de:0030-drops-205339},
  doi =		{10.4230/LIPIcs.SAT.2024.11},
  annote =	{Keywords: Knowledge compilation, top-down compilation, decision-DNNF Circuits}
}
Document
DOI: 10.4230/LIPIcs.SAT.2024.17
Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem

Authors: Yoichiro Iida, Tomohiro Sonobe, and Mary Inaba

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Parallelization of SAT solvers is an important technique for improving solver performance. The selection of the learnt clauses to share among parallel workers is crucial for its efficiency. Literal block distance (LBD) is often used to evaluate the quality of clauses to select. We propose a new method, Parallel Clause sharing based on graph Structure (PaCS), to select good clauses for sharing. First, we conducted three preliminary experiments to assess the performance of LBD in parallel clause sharing: a performance comparison between the LBD and clause size, an analysis of the utilization of shared clauses, and a comparison of the LBD values of shared clauses at originating and receiving workers. These experiments indicate that the LBD may not be optimal for learnt clause sharing. We attribute the results to the LBD’s inherent dependency on decision trees. Each parallel worker has a unique decision tree; thus, a sharing clause that is good for its originating worker may not be good for others. Therefore, we propose PaCS, a search-independent method that uses the graph structure derived from the input CNF of SAT problems. PaCS evaluates clauses using their edges' weight in the variable incidence graph. Using the input CNF’s graph is effective for parallel clause sharing because it is the common input for all parallel workers. Furthermore, using edge weight can select clauses whose variables' Boolean values are more likely to be determined. Performance evaluation experiments demonstrate that our strategy outperforms LBD by 4% in the number of solved instances and by 12% in PAR-2. This study opens avenues for further improvements in parallel-solving strategies using the structure of SAT problems and reinterpretations of the quality of learnt clauses.
Cite as

Yoichiro Iida, Tomohiro Sonobe, and Mary Inaba. Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem. In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 17:1-17:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{iida_et_al:LIPIcs.SAT.2024.17,
  author =	{Iida, Yoichiro and Sonobe, Tomohiro and Inaba, Mary},
  title =	{{Parallel Clause Sharing Strategy Based on Graph Structure of SAT Problem}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{17:1--17:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.17},
  URN =		{urn:nbn:de:0030-drops-205392},
  doi =		{10.4230/LIPIcs.SAT.2024.17},
  annote =	{Keywords: SAT Solver, Structure of SAT, Parallel application, Clause Learning}
}
Document
DOI: 10.4230/LIPIcs.SAT.2024.25
Trusted Scalable SAT Solving with On-The-Fly LRAT Checking

Authors: Dominik Schreiber

Published in: LIPIcs, Volume 305, 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)

Abstract
Recent advances have enabled powerful distributed SAT solvers to emit proofs of unsatisfiability, which renders them as trustworthy as sequential solvers. However, this mode of operation is still lacking behind conventional distributed solving in terms of scalability. We argue that the core limiting factor of such approaches is the requirement of a single, persistent artifact at the end of solving that is then checked independently (and sequentially). As an alternative, we propose a bottleneck-free setup that exploits recent advancements in producing and processing LRAT information to immediately check all solvers' reasoning on-the-fly during solving. In terms of clause sharing, our approach transfers the guarantee of a derived clause’s soundness from the sending to the receiving side via cryptographic signatures. Experiments with up to 2432 cores (32 nodes) indicate that our approach reduces the running time overhead incurred by proof checking by an order of magnitude, down to a median overhead of ≤ 42% over non trusted solving.
Cite as

Dominik Schreiber. Trusted Scalable SAT Solving with On-The-Fly LRAT Checking. In 27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 305, pp. 25:1-25:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{schreiber:LIPIcs.SAT.2024.25,
  author =	{Schreiber, Dominik},
  title =	{{Trusted Scalable SAT Solving with On-The-Fly LRAT Checking}},
  booktitle =	{27th International Conference on Theory and Applications of Satisfiability Testing (SAT 2024)},
  pages =	{25:1--25:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-334-8},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{305},
  editor =	{Chakraborty, Supratik and Jiang, Jie-Hong Roland},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SAT.2024.25},
  URN =		{urn:nbn:de:0030-drops-205477},
  doi =		{10.4230/LIPIcs.SAT.2024.25},
  annote =	{Keywords: SAT solving, distributed algorithms, proofs}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2021.5
ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety

Authors: Maxime Buyse, Rémi Delmas, and Youssef Hamadi

Published in: LIPIcs, Volume 194, 35th European Conference on Object-Oriented Programming (ECOOP 2021)

Abstract
This paper introduces Alpacas, a domain-specific language and algorithms aimed at architecture modeling and safety assessment for critical systems. It allows to study the effects of random and systematic faults on complex critical systems and their reliability. The underlying semantic framework of the language is Stochastic Guarded Transition Systems, for which Alpacas provides a feature-rich declarative modeling language and algorithms for symbolic analysis and Monte-Carlo simulation, allowing to compute safety indicators such as minimal cutsets and reliability. Built as a domain-specific language deeply embedded in Scala 3, Alpacas offers generic modeling capabilities and type-safety unparalleled in other existing safety assessment frameworks. This improved expressive power allows to address complex system modeling tasks, such as formalizing the architectural design space of a critical function, and exploring it to identify the most reliable variant. The features and algorithms of Alpacas are illustrated on a case study of a thrust allocation and power dispatch system for an electric vertical takeoff and landing aircraft.
Cite as

Maxime Buyse, Rémi Delmas, and Youssef Hamadi. ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety. In 35th European Conference on Object-Oriented Programming (ECOOP 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 194, pp. 5:1-5:29, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{buyse_et_al:LIPIcs.ECOOP.2021.5,
  author =	{Buyse, Maxime and Delmas, R\'{e}mi and Hamadi, Youssef},
  title =	{{ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety}},
  booktitle =	{35th European Conference on Object-Oriented Programming (ECOOP 2021)},
  pages =	{5:1--5:29},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-190-0},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{194},
  editor =	{M{\o}ller, Anders and Sridharan, Manu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2021.5},
  URN =		{urn:nbn:de:0030-drops-140487},
  doi =		{10.4230/LIPIcs.ECOOP.2021.5},
  annote =	{Keywords: Domain-Specific Language, Deep Embedding, Scala 3, Architecture Modelling, Safety Assessment, Static Analysis, Monte-Carlo Methods}
}
Document
Artifact
DOI: 10.4230/DARTS.7.2.14
ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety (Artifact)

Authors: Maxime Buyse, Rémi Delmas, and Youssef Hamadi

Published in: DARTS, Volume 7, Issue 2, Special Issue of the 35th European Conference on Object-Oriented Programming (ECOOP 2021)

Abstract
This artifact contains a virtual machine allowing to use ALPACAS, a domain-specific language and algorithms aimed at architecture modeling and safety assessment for critical systems. ALPACAS allows to study the effects of random and systematic faults on complex critical systems and their reliability. The underlying semantic framework of the language is Stochastic Guarded Transition Systems, for which ALPACAS provides a feature-rich declarative modeling language and algorithms for symbolic analysis and Monte-Carlo simulation, allowing to compute safety indicators such as minimal cutsets and reliability. Built as a domain-specific language deeply embedded in Scala 3, ALPACAS offers generic modeling capabilities and type-safety unparalleled in other existing safety assessment frameworks. This improved expressive power allows to address complex system modeling tasks, such as formalizing the architectural design space of a critical function, and exploring it to identify the most reliable variant. The features and algorithms of ALPACAS are illustrated on a case study of a thrust allocation and power dispatch system for an electric vertical takeoff and landing aircraft.
Cite as

Maxime Buyse, Rémi Delmas, and Youssef Hamadi. ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety (Artifact). In Special Issue of the 35th European Conference on Object-Oriented Programming (ECOOP 2021). Dagstuhl Artifacts Series (DARTS), Volume 7, Issue 2, pp. 14:1-14:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@Article{buyse_et_al:DARTS.7.2.14,
  author =	{Buyse, Maxime and Delmas, R\'{e}mi and Hamadi, Youssef},
  title =	{{ALPACAS: A Language for Parametric Assessment of Critical Architecture Safety (Artifact)}},
  pages =	{14:1--14:4},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2021},
  volume =	{7},
  number =	{2},
  editor =	{Buyse, Maxime and Delmas, R\'{e}mi and Hamadi, Youssef},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.7.2.14},
  URN =		{urn:nbn:de:0030-drops-140382},
  doi =		{10.4230/DARTS.7.2.14},
  annote =	{Keywords: Domain-Specific Language, Deep Embedding, Scala 3, Architecture Modelling, Safety Assessment, Static Analysis, Monte-Carlo Methods}
}
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