4 Search Results for "Ha, Vincent"

Document
Media Exposition
DOI: 10.4230/LIPIcs.SoCG.2023.62
Godzilla Onions: A Skit and Applet to Explain Euclidean Half-Plane Fractional Cascading (Media Exposition)

Authors: Richard Berger, Vincent Ha, David Kratz, Michael Lin, Jeremy Moyer, and Christopher J. Tralie

Published in: LIPIcs, Volume 258, 39th International Symposium on Computational Geometry (SoCG 2023)

Abstract
We provide a skit and an applet to illustrate fractional cascading in the context of half-plane range search for points in the Euclidean plane, which takes O(log N + h) output-sensitive time. In the video, a group of news anchors struggles to find the correct data structure to efficiently send out an early warning to the residents of Philadelphia who will be overtaken by a marching line of Godzillas. After exploring several options, the group eventually settles on onions and fractional cascading, only to discover that they themselves are in the line of fire! In the applet, we show step by step details of preprocessing to build the onions with fractional cascading and the subsequent query of the "Godzilla line" against the onion layers. Our video skit and applet can be found at https://ctralie.github.io/GodzillaOnions/
Cite as

Richard Berger, Vincent Ha, David Kratz, Michael Lin, Jeremy Moyer, and Christopher J. Tralie. Godzilla Onions: A Skit and Applet to Explain Euclidean Half-Plane Fractional Cascading (Media Exposition). In 39th International Symposium on Computational Geometry (SoCG 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 258, pp. 62:1-62:3, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)

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@InProceedings{berger_et_al:LIPIcs.SoCG.2023.62,
  author =	{Berger, Richard and Ha, Vincent and Kratz, David and Lin, Michael and Moyer, Jeremy and Tralie, Christopher J.},
  title =	{{Godzilla Onions: A Skit and Applet to Explain Euclidean Half-Plane Fractional Cascading}},
  booktitle =	{39th International Symposium on Computational Geometry (SoCG 2023)},
  pages =	{62:1--62:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-273-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{258},
  editor =	{Chambers, Erin W. and Gudmundsson, Joachim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2023.62},
  URN =		{urn:nbn:de:0030-drops-179129},
  doi =		{10.4230/LIPIcs.SoCG.2023.62},
  annote =	{Keywords: convex hulls, onions, fractional cascading, visualization, d3}
}
Document
DOI: 10.4230/LITES.8.2.2
Swarms of Mobile Robots: Towards Versatility with Safety

Authors: Pierre Courtieu, Lionel Rieg, Sébastien Tixeuil, and Xavier Urbain

Published in: LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems. Leibniz Transactions on Embedded Systems, Volume 8, Issue 2

Abstract
We present Pactole, a formal framework to design and prove the correctness of protocols (or the impossibility of their existence) that target mobile robotic swarms. Unlike previous approaches, our methodology unifies in a single formalism the execution model, the problem specification, the protocol, and its proof of correctness. The Pactole framework makes use of the Coq proof assistant, and is specially targeted at protocol designers and problem specifiers, so that a common unambiguous language is used from the very early stages of protocol development. We stress the underlying framework design principles to enable high expressivity and modularity, and provide concrete examples about how the Pactole framework can be used to tackle actual problems, some previously addressed by the Distributed Computing community, but also new problems, while being certified correct.
Cite as

Pierre Courtieu, Lionel Rieg, Sébastien Tixeuil, and Xavier Urbain. Swarms of Mobile Robots: Towards Versatility with Safety. In LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems. Leibniz Transactions on Embedded Systems, Volume 8, Issue 2, pp. 02:1-02:36, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)

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@Article{courtieu_et_al:LITES.8.2.2,
  author =	{Courtieu, Pierre and Rieg, Lionel and Tixeuil, S\'{e}bastien and Urbain, Xavier},
  title =	{{Swarms of Mobile Robots: Towards Versatility with Safety}},
  booktitle =	{LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems},
  pages =	{02:1--02:36},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2022},
  volume =	{8},
  number =	{2},
  editor =	{Courtieu, Pierre and Rieg, Lionel and Tixeuil, S\'{e}bastien and Urbain, Xavier},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES.8.2.2},
  doi =		{10.4230/LITES.8.2.2},
  annote =	{Keywords: distributed algorithm, mobile autonomous robots, formal proof}
}
Document
DOI: 10.4230/LITES-v003-i001-a005
A Survey on Static Cache Analysis for Real-Time Systems

Authors: Mingsong Lv, Nan Guan, Jan Reineke, Reinhard Wilhelm, and Wang Yi

Published in: LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1

Abstract
Real-time systems are reactive computer systems that must produce their reaction to a stimulus within given time bounds. A vital verification requirement is to estimate the Worst-Case Execution Time (WCET) of programs. These estimates are then used to predict the timing behavior of the overall system. The execution time of a program heavily depends on the underlying hardware, among which cache has the biggest influence. Analyzing cache behavior is very challenging due to the versatile cache features and complex execution environment. This article provides a survey on static cache analysis for real-time systems. We first present the challenges and static analysis techniques for independent programs with respect to different cache features. Then, the discussion is extended to cache analysis in complex execution environment, followed by a survey of existing tools based on static techniques for cache analysis. An outlook for future research is provided at last.
Cite as

Mingsong Lv, Nan Guan, Jan Reineke, Reinhard Wilhelm, and Wang Yi. A Survey on Static Cache Analysis for Real-Time Systems. In LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1, pp. 05:1-05:48, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2016)

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@Article{lv_et_al:LITES-v003-i001-a005,
  author =	{Lv, Mingsong and Guan, Nan and Reineke, Jan and Wilhelm, Reinhard and Yi, Wang},
  title =	{{A Survey on Static Cache Analysis for Real-Time Systems}},
  booktitle =	{LITES, Volume 3, Issue 1 (2016)},
  pages =	{05:1--05:48},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2016},
  volume =	{3},
  number =	{1},
  editor =	{Lv, Mingsong and Guan, Nan and Reineke, Jan and Wilhelm, Reinhard and Yi, Wang},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v003-i001-a005},
  doi =		{10.4230/LITES-v003-i001-a005},
  annote =	{Keywords: Hard real-time, Cache analysis, Worst-case execution time}
}
Document
DOI: 10.4230/LITES-v001-i001-a001
A Comparison between Fixed Priority and EDF Scheduling accounting for Cache Related Pre-emption Delays

Authors: Will Lunniss, Sebastian Altmeyer, and Robert I. Davis

Published in: LITES, Volume 1, Issue 1 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 1

Abstract
In multitasking real-time systems, the choice of scheduling algorithm is an important factor to ensure that response time requirements are met while maximising limited system resources. Two popular scheduling algorithms include fixed priority (FP) and earliest deadline first (EDF). While they have been studied in great detail before, they have not been compared when taking into account cache related pre-emption delays (CRPD). Memory and cache are split into a number of blocks containing instructions and data. During a pre-emption, cache blocks from the pre-empting task can evict those of the pre-empted task. When the pre-empted task is resumed, if it then has to re-load the evicted blocks, CRPD are introduced which then affect the schedulability of the task. In this paper we compare FP and EDF scheduling algorithms in the presence of CRPD using the state-of-the-art CRPD analysis. We find that when CRPD is accounted for, the performance gains offered by EDF over FP, while still notable, are diminished. Furthermore, we find that under scenarios that cause relatively high CRPD, task layout optimisation techniques can be applied to allow FP to schedule tasksets at a similar processor utilisation to EDF. Thus making the choice of the task layout in memory as important as the choice of scheduling algorithm. This is very relevant for industry, as it is much cheaper and simpler to adjust the task layout through the linker than it is to switch the scheduling algorithm.
Cite as

Will Lunniss, Sebastian Altmeyer, and Robert I. Davis. A Comparison between Fixed Priority and EDF Scheduling accounting for Cache Related Pre-emption Delays. In LITES, Volume 1, Issue 1 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 1, pp. 01:1-01:24, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2014)

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@Article{lunniss_et_al:LITES-v001-i001-a001,
  author =	{Lunniss, Will and Altmeyer, Sebastian and Davis, Robert I.},
  title =	{{A Comparison between Fixed Priority and EDF Scheduling accounting for Cache Related Pre-emption Delays}},
  booktitle =	{LITES, Volume 1, Issue 1 (2014)},
  pages =	{01:1--01:24},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2014},
  volume =	{1},
  number =	{1},
  editor =	{Lunniss, Will and Altmeyer, Sebastian and Davis, Robert I.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v001-i001-a001},
  doi =		{10.4230/LITES-v001-i001-a001},
  annote =	{Keywords: Real-time systems, Fixed priority, EDF, Pre-emptive scheduling, Cache related pre-emption delays}
}
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