Search Results

Documents authored by Bender, Michael A.


Document
The Safe and Effective Use of Low-Assurance Predictions in Safety-Critical Systems

Authors: Kunal Agrawal, Sanjoy Baruah, Michael A. Bender, and Alberto Marchetti-Spaccamela

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)


Abstract
The algorithm-design paradigm of algorithms using predictions is explored as a means of incorporating the computations of lower-assurance components (such as machine-learning based ones) into safety-critical systems that must have their correctness validated to very high levels of assurance. The paradigm is applied to two simple example applications that are relevant to the real-time systems community: energy-aware scheduling, and classification using ML-based classifiers in conjunction with more reliable but slower deterministic classifiers. It is shown how algorithms using predictions achieve much-improved performance when the low-assurance computations are correct, at a cost of no more than a slight performance degradation even when they turn out to be completely wrong.

Cite as

Kunal Agrawal, Sanjoy Baruah, Michael A. Bender, and Alberto Marchetti-Spaccamela. The Safe and Effective Use of Low-Assurance Predictions in Safety-Critical Systems. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 3:1-3:19, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{agrawal_et_al:LIPIcs.ECRTS.2023.3,
  author =	{Agrawal, Kunal and Baruah, Sanjoy and Bender, Michael A. and Marchetti-Spaccamela, Alberto},
  title =	{{The Safe and Effective Use of Low-Assurance Predictions in Safety-Critical Systems}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{3:1--3:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.3},
  URN =		{urn:nbn:de:0030-drops-180323},
  doi =		{10.4230/LIPIcs.ECRTS.2023.3},
  annote =	{Keywords: Algorithms using predictions, robust scheduling, energy minimization, classification, on-line scheduling}
}
Document
When Are Cache-Oblivious Algorithms Cache Adaptive? A Case Study of Matrix Multiplication and Sorting

Authors: Arghya Bhattacharya, Abiyaz Chowdhury, Helen Xu, Rathish Das, Rezaul A. Chowdhury, Rob Johnson, Rishab Nithyanand, and Michael A. Bender

Published in: LIPIcs, Volume 244, 30th Annual European Symposium on Algorithms (ESA 2022)


Abstract
Cache-adaptive algorithms are a class of algorithms that achieve optimal utilization of dynamically changing memory. These memory fluctuations are the norm in today’s multi-threaded shared-memory machines and time-sharing caches. Bender et al. [Bender et al., 2014] proved that many cache-oblivious algorithms are optimally cache-adaptive, but that some cache-oblivious algorithms can be relatively far from optimally cache-adaptive on worst-case memory fluctuations. This worst-case gap between cache obliviousness and cache adaptivity depends on a highly-structured, adversarial memory profile. Existing cache-adaptive analysis does not predict the relative performance of cache-oblivious and cache-adaptive algorithms on non-adversarial profiles. Does the worst-case gap appear in practice, or is it an artifact of an unrealistically powerful adversary? This paper sheds light on the question of whether cache-oblivious algorithms can effectively adapt to realistically fluctuating memory sizes; the paper focuses on matrix multiplication and sorting. The two matrix-multiplication algorithms in this paper are canonical examples of "(a, b, c)-regular" cache-oblivious algorithms, which underlie much of the existing theory on cache-adaptivity. Both algorithms have the same asymptotic I/O performance when the memory size remains fixed, but one is optimally cache-adaptive, and the other is not. In our experiments, we generate both adversarial and non-adversarial memory workloads. The performance gap between the algorithms for matrix multiplication grows with problem size (up to 3.8×) on the adversarial profiles, but the gap does not grow with problem size (stays at 2×) on non-adversarial profiles. The sorting algorithms in this paper are not "(a, b, c)-regular," but they have been well-studied in the classical external-memory model when the memory size does not fluctuate. The relative performance of a non-oblivious (cache-aware) sorting algorithm degrades with the problem size: it incurs up to 6 × the number of disk I/Os compared to an oblivious adaptive algorithm on both adversarial and non-adversarial profiles. To summarize, in all our experiments, the cache-oblivious matrix-multiplication and sorting algorithms that we tested empirically adapt well to memory fluctuations. We conjecture that cache-obliviousness will empirically help achieve adaptivity for other problems with similar structures.

Cite as

Arghya Bhattacharya, Abiyaz Chowdhury, Helen Xu, Rathish Das, Rezaul A. Chowdhury, Rob Johnson, Rishab Nithyanand, and Michael A. Bender. When Are Cache-Oblivious Algorithms Cache Adaptive? A Case Study of Matrix Multiplication and Sorting. In 30th Annual European Symposium on Algorithms (ESA 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 244, pp. 16:1-16:17, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{bhattacharya_et_al:LIPIcs.ESA.2022.16,
  author =	{Bhattacharya, Arghya and Chowdhury, Abiyaz and Xu, Helen and Das, Rathish and Chowdhury, Rezaul A. and Johnson, Rob and Nithyanand, Rishab and Bender, Michael A.},
  title =	{{When Are Cache-Oblivious Algorithms Cache Adaptive? A Case Study of Matrix Multiplication and Sorting}},
  booktitle =	{30th Annual European Symposium on Algorithms (ESA 2022)},
  pages =	{16:1--16:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-247-1},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{244},
  editor =	{Chechik, Shiri and Navarro, Gonzalo and Rotenberg, Eva 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.2022.16},
  URN =		{urn:nbn:de:0030-drops-169543},
  doi =		{10.4230/LIPIcs.ESA.2022.16},
  annote =	{Keywords: Cache-adaptive algorithms, cache-oblivious algorithms}
}
Document
What Does Dynamic Optimality Mean in External Memory?

Authors: Michael A. Bender, Martín Farach-Colton, and William Kuszmaul

Published in: LIPIcs, Volume 215, 13th Innovations in Theoretical Computer Science Conference (ITCS 2022)


Abstract
A data structure A is said to be dynamically optimal over a class of data structures 𝒞 if A is constant-competitive with every data structure C ∈ 𝒞. Much of the research on binary search trees in the past forty years has focused on studying dynamic optimality over the class of binary search trees that are modified via rotations (and indeed, the question of whether splay trees are dynamically optimal has gained notoriety as the so-called dynamic-optimality conjecture). Recently, researchers have extended this to consider dynamic optimality over certain classes of external-memory search trees. In particular, Demaine, Iacono, Koumoutsos, and Langerman propose a class of external-memory trees that support a notion of tree rotations, and then give an elegant data structure, called the Belga B-tree, that is within an O(log log N)-factor of being dynamically optimal over this class. In this paper, we revisit the question of how dynamic optimality should be defined in external memory. A defining characteristic of external-memory data structures is that there is a stark asymmetry between queries and inserts/updates/deletes: by making the former slightly asymptotically slower, one can make the latter significantly asymptotically faster (even allowing for operations with sub-constant amortized I/Os). This asymmetry makes it so that rotation-based search trees are not optimal (or even close to optimal) in insert/update/delete-heavy external-memory workloads. To study dynamic optimality for such workloads, one must consider a different class of data structures. The natural class of data structures to consider are what we call buffered-propagation trees. Such trees can adapt dynamically to the locality properties of an input sequence in order to optimize the interactions between different inserts/updates/deletes and queries. We also present a new form of beyond-worst-case analysis that allows for us to formally study a continuum between static and dynamic optimality. Finally, we give a novel data structure, called the Jεllo Tree, that is statically optimal and that achieves dynamic optimality for a large natural class of inputs defined by our beyond-worst-case analysis.

Cite as

Michael A. Bender, Martín Farach-Colton, and William Kuszmaul. What Does Dynamic Optimality Mean in External Memory?. In 13th Innovations in Theoretical Computer Science Conference (ITCS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 215, pp. 18:1-18:23, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{bender_et_al:LIPIcs.ITCS.2022.18,
  author =	{Bender, Michael A. and Farach-Colton, Mart{\'\i}n and Kuszmaul, William},
  title =	{{What Does Dynamic Optimality Mean in External Memory?}},
  booktitle =	{13th Innovations in Theoretical Computer Science Conference (ITCS 2022)},
  pages =	{18:1--18:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-217-4},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{215},
  editor =	{Braverman, Mark},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2022.18},
  URN =		{urn:nbn:de:0030-drops-156145},
  doi =		{10.4230/LIPIcs.ITCS.2022.18},
  annote =	{Keywords: Dynamic optimality, external memory, buffer propagation, search trees}
}
Document
Incremental Edge Orientation in Forests

Authors: Michael A. Bender, Tsvi Kopelowitz, William Kuszmaul, Ely Porat, and Clifford Stein

Published in: LIPIcs, Volume 204, 29th Annual European Symposium on Algorithms (ESA 2021)


Abstract
For any forest G = (V, E) it is possible to orient the edges E so that no vertex in V has out-degree greater than 1. This paper considers the incremental edge-orientation problem, in which the edges E arrive over time and the algorithm must maintain a low-out-degree edge orientation at all times. We give an algorithm that maintains a maximum out-degree of 3 while flipping at most O(log log n) edge orientations per edge insertion, with high probability in n. The algorithm requires worst-case time O(log n log log n) per insertion, and takes amortized time O(1). The previous state of the art required up to O(log n / log log n) edge flips per insertion. We then apply our edge-orientation results to the problem of dynamic Cuckoo hashing. The problem of designing simple families ℋ of hash functions that are compatible with Cuckoo hashing has received extensive attention. These families ℋ are known to satisfy static guarantees, but do not come typically with dynamic guarantees for the running time of inserts and deletes. We show how to transform static guarantees (for 1-associativity) into near-state-of-the-art dynamic guarantees (for O(1)-associativity) in a black-box fashion. Rather than relying on the family ℋ to supply randomness, as in past work, we instead rely on randomness within our table-maintenance algorithm.

Cite as

Michael A. Bender, Tsvi Kopelowitz, William Kuszmaul, Ely Porat, and Clifford Stein. Incremental Edge Orientation in Forests. In 29th Annual European Symposium on Algorithms (ESA 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 204, pp. 12:1-12:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{bender_et_al:LIPIcs.ESA.2021.12,
  author =	{Bender, Michael A. and Kopelowitz, Tsvi and Kuszmaul, William and Porat, Ely and Stein, Clifford},
  title =	{{Incremental Edge Orientation in Forests}},
  booktitle =	{29th Annual European Symposium on Algorithms (ESA 2021)},
  pages =	{12:1--12:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-204-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{204},
  editor =	{Mutzel, Petra and Pagh, Rasmus 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.2021.12},
  URN =		{urn:nbn:de:0030-drops-145933},
  doi =		{10.4230/LIPIcs.ESA.2021.12},
  annote =	{Keywords: edge orientation, graph algorithms, Cuckoo hashing, hash functions}
}
Document
Complete Volume
LIPIcs, Volume 144, ESA'19, Complete Volume

Authors: Michael A. Bender, Ola Svensson, and Grzegorz Herman

Published in: LIPIcs, Volume 144, 27th Annual European Symposium on Algorithms (ESA 2019)


Abstract
LIPIcs, Volume 144, ESA'19, Complete Volume

Cite as

Michael A. Bender, Ola Svensson, and Grzegorz Herman. LIPIcs, Volume 144, ESA'19, Complete Volume. In 27th Annual European Symposium on Algorithms (ESA 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 144, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@Proceedings{bender_et_al:LIPIcs.ESA.2019,
  title =	{{LIPIcs, Volume 144, ESA'19, Complete Volume}},
  booktitle =	{27th Annual European Symposium on Algorithms (ESA 2019)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-124-5},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{144},
  editor =	{Bender, Michael A. and Svensson, Ola 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.2019},
  URN =		{urn:nbn:de:0030-drops-113004},
  doi =		{10.4230/LIPIcs.ESA.2019},
  annote =	{Keywords: Applied computing, Transportation; Computing methodologies, Algebraic algorithms; Hardware, External storage; Human-centered computing, Graph drawings}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Michael A. Bender, Ola Svensson, and Grzegorz Herman

Published in: LIPIcs, Volume 144, 27th Annual European Symposium on Algorithms (ESA 2019)


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

Michael A. Bender, Ola Svensson, and Grzegorz Herman. Front Matter, Table of Contents, Preface, Conference Organization. In 27th Annual European Symposium on Algorithms (ESA 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 144, pp. 0:i-0:xx, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2019)


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@InProceedings{bender_et_al:LIPIcs.ESA.2019.0,
  author =	{Bender, Michael A. and Svensson, Ola and Herman, Grzegorz},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{27th Annual European Symposium on Algorithms (ESA 2019)},
  pages =	{0:i--0:xx},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-124-5},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{144},
  editor =	{Bender, Michael A. and Svensson, Ola 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.2019.0},
  URN =		{urn:nbn:de:0030-drops-111215},
  doi =		{10.4230/LIPIcs.ESA.2019.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Resource Optimization for Program Committee Members: A Subreview Article

Authors: Michael A. Bender, Samuel McCauley, Bertrand Simon, Shikha Singh, and Frédéric Vivien

Published in: LIPIcs, Volume 49, 8th International Conference on Fun with Algorithms (FUN 2016)


Abstract
This paper formalizes a resource-allocation problem that is all too familiar to the seasoned program-committee member. For each submission j that the PC member has the honor of reviewing, there is a choice. The PC member can spend the time to review submission j in detail on his/her own at a cost of C_i. Alternatively, the PC member can spend the time to identify and contact peers, hoping to recruit them as subreviewers, at a cost of 1 per subreviewer. These potential subreviewers have a certain probability of rejecting each review request, and this probability increases as time goes on. Once the PC member runs out of time or unasked experts, he/she is forced to review the paper without outside assistance. This paper gives optimal solutions to several variations of the scheduling-reviewers problem. Most of the solutions from this paper are based on an iterated log function of C_i. In particular, with k rounds, the optimal solution sends the k-iterated log of C_i requests in the first round, the (k-1)-iterated log in the second round, and so forth. One of the contributions of this paper is solving this problem exactly, even when rejection probabilities may increase. Naturally, PC members must make an integral number of subreview requests. This paper gives, as an intermediate result, a linear-time algorithm to transform the artificial problem in which one can send fractional requests into the less-artificial problem in which one sends an integral number of requests. Finally, this paper considers the case where the PC member knows nothing about the probability that a potential subreviewer agrees to review the paper. This paper gives an approximation algorithm for this case, whose bounds improve as the number of rounds increases.

Cite as

Michael A. Bender, Samuel McCauley, Bertrand Simon, Shikha Singh, and Frédéric Vivien. Resource Optimization for Program Committee Members: A Subreview Article. In 8th International Conference on Fun with Algorithms (FUN 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 49, pp. 7:1-7:20, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2016)


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@InProceedings{bender_et_al:LIPIcs.FUN.2016.7,
  author =	{Bender, Michael A. and McCauley, Samuel and Simon, Bertrand and Singh, Shikha and Vivien, Fr\'{e}d\'{e}ric},
  title =	{{Resource Optimization for Program Committee Members: A Subreview Article}},
  booktitle =	{8th International Conference on Fun with Algorithms (FUN 2016)},
  pages =	{7:1--7:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-005-7},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{49},
  editor =	{Demaine, Erik D. and Grandoni, Fabrizio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FUN.2016.7},
  URN =		{urn:nbn:de:0030-drops-58872},
  doi =		{10.4230/LIPIcs.FUN.2016.7},
  annote =	{Keywords: Scheduling, Delegation, Subreviews}
}
Document
04301 Abstracts Collection – Cache-Oblivious and Cache-Aware Algorithms

Authors: Lars Arge, Michael A. Bender, Erik Demaine, Charles Leiserson, and Kurt Mehlhorn

Published in: Dagstuhl Seminar Proceedings, Volume 4301, Cache-Oblivious and Cache-Aware Algorithms (2005)


Abstract
The Dagstuhl Seminar 04301 ``Cache-Oblivious and Cache-Aware Algorithms'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl, from 18.07.2004 to 23.07.2004. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.

Cite as

Lars Arge, Michael A. Bender, Erik Demaine, Charles Leiserson, and Kurt Mehlhorn. 04301 Abstracts Collection – Cache-Oblivious and Cache-Aware Algorithms. In Cache-Oblivious and Cache-Aware Algorithms. Dagstuhl Seminar Proceedings, Volume 4301, pp. 1-14, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2005)


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@InProceedings{arge_et_al:DagSemProc.04301.1,
  author =	{Arge, Lars and Bender, Michael A. and Demaine, Erik and Leiserson, Charles and Mehlhorn, Kurt},
  title =	{{04301 Abstracts Collection – Cache-Oblivious and Cache-Aware Algorithms}},
  booktitle =	{Cache-Oblivious and Cache-Aware Algorithms},
  pages =	{1--14},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2005},
  volume =	{4301},
  editor =	{Lars Arge and Michael A. Bender and Erik Demaine and Charles Leiserson and Kurt Mehlhorn},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.04301.1},
  URN =		{urn:nbn:de:0030-drops-1576},
  doi =		{10.4230/DagSemProc.04301.1},
  annote =	{Keywords: Cache oblivious , cache aware , external memory , I/O-efficient algorithms , data structures}
}
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