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Documents authored by Tiwari, Ashish


Document
Invited Paper
Love Thy Neighbor: V-Formation as a Problem of Model Predictive Control (Invited Paper)

Authors: Junxing Yang, Radu Grosu, Scott A. Smolka, and Ashish Tiwari

Published in: LIPIcs, Volume 59, 27th International Conference on Concurrency Theory (CONCUR 2016)


Abstract
We present a new formulation of the V-formation problem for migrating birds in terms of model predictive control (MPC). In our approach, to drive a collection of birds towards a desired formation, an optimal velocity adjustment (acceleration) is performed at each time-step on each bird's current velocity using a model-based prediction window of $T$ time-steps. We present both centralized and distributed versions of this approach. The optimization criteria we consider are based on fitness metrics of candidate accelerations that birds in a V-formations are known to benefit from, including velocity matching, clear view, and upwash benefit. We validate our MPC-based approach by showing that for a significant majority of simulation runs, the flock succeeds in forming the desired formation. Our results help to better understand the emergent behavior of formation flight, and provide a control strategy for flocks of autonomous aerial vehicles.

Cite as

Junxing Yang, Radu Grosu, Scott A. Smolka, and Ashish Tiwari. Love Thy Neighbor: V-Formation as a Problem of Model Predictive Control (Invited Paper). In 27th International Conference on Concurrency Theory (CONCUR 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 59, pp. 4:1-4:5, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{yang_et_al:LIPIcs.CONCUR.2016.4,
  author =	{Yang, Junxing and Grosu, Radu and Smolka, Scott A. and Tiwari, Ashish},
  title =	{{Love Thy Neighbor: V-Formation as a Problem of Model Predictive Control}},
  booktitle =	{27th International Conference on Concurrency Theory (CONCUR 2016)},
  pages =	{4:1--4:5},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-017-0},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{59},
  editor =	{Desharnais, Jos\'{e}e and Jagadeesan, Radha},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2016.4},
  URN =		{urn:nbn:de:0030-drops-61896},
  doi =		{10.4230/LIPIcs.CONCUR.2016.4},
  annote =	{Keywords: bird flocking, v-formation, model predictive control, particle swarm optimization}
}
Document
Two-Restricted One Context Unification is in Polynomial Time

Authors: Adrià Gascón, Manfred Schmidt-Schauß, and Ashish Tiwari

Published in: LIPIcs, Volume 41, 24th EACSL Annual Conference on Computer Science Logic (CSL 2015)


Abstract
One Context Unification (1CU) extends first-order unification by introducing a single context variable. This problem was recently shown to be in NP, but it is not known to be solvable in polynomial time. We show that the case of 1CU where the context variable occurs at most twice in the input (1CU2r) is solvable in polynomial time. Moreover, a polynomial representation of all solutions can also be computed in polynomial time. The 1CU2r problem is important as it is used as a subroutine in polynomial time algorithms for several more-general classes of 1CU problem. Our algorithm can be seen as an extension of the usual rules of first-order unification and can be used to solve related problems in polynomial time, such as first-order unification of two terms that tolerates one clash. All our results assume that the input terms are represented as Directed Acyclic Graphs.

Cite as

Adrià Gascón, Manfred Schmidt-Schauß, and Ashish Tiwari. Two-Restricted One Context Unification is in Polynomial Time. In 24th EACSL Annual Conference on Computer Science Logic (CSL 2015). Leibniz International Proceedings in Informatics (LIPIcs), Volume 41, pp. 405-422, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)


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@InProceedings{gascon_et_al:LIPIcs.CSL.2015.405,
  author =	{Gasc\'{o}n, Adri\`{a} and Schmidt-Schau{\ss}, Manfred and Tiwari, Ashish},
  title =	{{Two-Restricted One Context Unification is in Polynomial Time}},
  booktitle =	{24th EACSL Annual Conference on Computer Science Logic (CSL 2015)},
  pages =	{405--422},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-90-3},
  ISSN =	{1868-8969},
  year =	{2015},
  volume =	{41},
  editor =	{Kreutzer, Stephan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2015.405},
  URN =		{urn:nbn:de:0030-drops-54289},
  doi =		{10.4230/LIPIcs.CSL.2015.405},
  annote =	{Keywords: context unification, first-order unification, deduction, type checking}
}
Document
Complete Volume
LIPIcs, Volume 15, RTA'12, Complete Volume

Authors: Ashish Tiwari

Published in: LIPIcs, Volume 15, 23rd International Conference on Rewriting Techniques and Applications (RTA'12) (2012)


Abstract
LIPIcs, Volume 15, RTA'12, Complete Volume

Cite as

23rd International Conference on Rewriting Techniques and Applications (RTA'12). Leibniz International Proceedings in Informatics (LIPIcs), Volume 15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)


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@Proceedings{tiwari:LIPIcs.RTA.2012,
  title =	{{LIPIcs, Volume 15, RTA'12, Complete Volume}},
  booktitle =	{23rd International Conference on Rewriting Techniques and Applications (RTA'12)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-38-5},
  ISSN =	{1868-8969},
  year =	{2013},
  volume =	{15},
  editor =	{Tiwari, Ashish},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.RTA.2012},
  URN =		{urn:nbn:de:0030-drops-41090},
  doi =		{10.4230/LIPIcs.RTA.2012},
  annote =	{Keywords: Programming Techniques, Software Engineering, Programming Languages, Computation by Abstract Devices, Analysis of Algorithms and Problem Complexity Logics and Meanings of Programs, Mathematical Logic and Formal Languages, Symbolic and Algebraic Manipulation, Artificial Intelligence}
}
Document
Front Matter
RTA 2012 Proceedings Frontmatter

Authors: Ashish Tiwari

Published in: LIPIcs, Volume 15, 23rd International Conference on Rewriting Techniques and Applications (RTA'12) (2012)


Abstract
Frontmatter, Table of Contents, Conference Organization, External Reviewers, Author Index.

Cite as

23rd International Conference on Rewriting Techniques and Applications (RTA'12). Leibniz International Proceedings in Informatics (LIPIcs), Volume 15, pp. i-xiii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)


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@InProceedings{tiwari:LIPIcs.RTA.2012.i,
  author =	{Tiwari, Ashish},
  title =	{{RTA 2012 Proceedings Frontmatter}},
  booktitle =	{23rd International Conference on Rewriting Techniques and Applications (RTA'12)},
  pages =	{i--xiii},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-38-5},
  ISSN =	{1868-8969},
  year =	{2012},
  volume =	{15},
  editor =	{Tiwari, Ashish},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.RTA.2012.i},
  URN =		{urn:nbn:de:0030-drops-35033},
  doi =		{10.4230/LIPIcs.RTA.2012.i},
  annote =	{Keywords: Frontmatter, Table of Contents, Conference Organization, External Reviewers, Author Index, RTA 2012, proceedings}
}
Document
Rewriting in Practice

Authors: Ashish Tiwari

Published in: LIPIcs, Volume 10, 22nd International Conference on Rewriting Techniques and Applications (RTA'11) (2011)


Abstract
We discuss applications of rewriting in three different areas: design and analysis of algorithms, theorem proving and term rewriting, and modeling and analysis of biological processes.

Cite as

Ashish Tiwari. Rewriting in Practice. In 22nd International Conference on Rewriting Techniques and Applications (RTA'11). Leibniz International Proceedings in Informatics (LIPIcs), Volume 10, pp. 3-8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{tiwari:LIPIcs.RTA.2011.3,
  author =	{Tiwari, Ashish},
  title =	{{Rewriting in Practice}},
  booktitle =	{22nd International Conference on Rewriting Techniques and Applications (RTA'11)},
  pages =	{3--8},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-30-9},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{10},
  editor =	{Schmidt-Schauss, Manfred},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.RTA.2011.3},
  URN =		{urn:nbn:de:0030-drops-31326},
  doi =		{10.4230/LIPIcs.RTA.2011.3},
  annote =	{Keywords: Rewriting, Polynomial constraints, Biochemical reaction networks}
}
Document
Deductive Verification of Continuous Dynamical Systems

Authors: Ankur Taly and Ashish Tiwari

Published in: LIPIcs, Volume 4, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (2009)


Abstract
We define the notion of inductive invariants for continuous dynamical systems and use it to present inference rules for safety verification of polynomial continuous dynamical systems. We present two different sound and complete inference rules, but neither of these rules can be effectively applied. We then present several simpler and practical inference rules that are sound and relatively complete for different classes of inductive invariants. The simpler inference rules can be effectively checked when all involved sets are semi-algebraic.

Cite as

Ankur Taly and Ashish Tiwari. Deductive Verification of Continuous Dynamical Systems. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science. Leibniz International Proceedings in Informatics (LIPIcs), Volume 4, pp. 383-394, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)


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@InProceedings{taly_et_al:LIPIcs.FSTTCS.2009.2334,
  author =	{Taly, Ankur and Tiwari, Ashish},
  title =	{{Deductive Verification of Continuous Dynamical Systems}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science},
  pages =	{383--394},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-13-2},
  ISSN =	{1868-8969},
  year =	{2009},
  volume =	{4},
  editor =	{Kannan, Ravi and Narayan Kumar, K.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2009.2334},
  URN =		{urn:nbn:de:0030-drops-23342},
  doi =		{10.4230/LIPIcs.FSTTCS.2009.2334},
  annote =	{Keywords: Deductive Verification, inductive invariants, continuous and hybrid dynamical systems, Theory of Reals}
}
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