6 Search Results for "Kumar, Naveen"

Document
DOI: 10.4230/LIPIcs.ISAAC.2020.41
Multicommodity Flows in Planar Graphs with Demands on Faces

Authors: Nikhil Kumar

Published in: LIPIcs, Volume 181, 31st International Symposium on Algorithms and Computation (ISAAC 2020)

Abstract
We consider the problem of multicommodity flows in planar graphs. Seymour [Seymour, 1981] showed that if the union of supply and demand graphs is planar, then the cut condition is also sufficient for routing demands. Okamura-Seymour [Okamura and Seymour, 1981] showed that if the supply graph is planar and all demands are incident on one face, then again the cut condition is sufficient for routing demands. We consider a common generalization of these settings where the end points of each demand are on the same face of the planar graph. We show that if the source sink pairs on each face of the graph are such that sources and sinks appear contiguously on the cycle bounding the face, then the flow cut gap is at most 3. We come up with a notion of approximating demands on a face by convex combination of laminar demands to prove this result.
Cite as

Nikhil Kumar. Multicommodity Flows in Planar Graphs with Demands on Faces. In 31st International Symposium on Algorithms and Computation (ISAAC 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 181, pp. 41:1-41:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{kumar:LIPIcs.ISAAC.2020.41,
  author =	{Kumar, Nikhil},
  title =	{{Multicommodity Flows in Planar Graphs with Demands on Faces}},
  booktitle =	{31st International Symposium on Algorithms and Computation (ISAAC 2020)},
  pages =	{41:1--41:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-173-3},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{181},
  editor =	{Cao, Yixin and Cheng, Siu-Wing and Li, Minming},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2020.41},
  URN =		{urn:nbn:de:0030-drops-133857},
  doi =		{10.4230/LIPIcs.ISAAC.2020.41},
  annote =	{Keywords: Combinatorial Optimization, Multicommodity Flow, Network Design}
}
Document
DOI: 10.4230/LIPIcs.ESA.2020.55
Dual Half-Integrality for Uncrossable Cut Cover and Its Application to Maximum Half-Integral Flow

Authors: Naveen Garg and Nikhil Kumar

Published in: LIPIcs, Volume 173, 28th Annual European Symposium on Algorithms (ESA 2020)

Abstract
Given an edge weighted graph and a forest F, the 2-edge connectivity augmentation problem is to pick a minimum weighted set of edges, E', such that every connected component of E' ∪ F is 2-edge connected. Williamson et al. gave a 2-approximation algorithm (WGMV) for this problem using the primal-dual schema. We show that when edge weights are integral, the WGMV procedure can be modified to obtain a half-integral dual. The 2-edge connectivity augmentation problem has an interesting connection to routing flow in graphs where the union of supply and demand is planar. The half-integrality of the dual leads to a tight 2-approximate max-half-integral-flow min-multicut theorem.
Cite as

Naveen Garg and Nikhil Kumar. Dual Half-Integrality for Uncrossable Cut Cover and Its Application to Maximum Half-Integral Flow. In 28th Annual European Symposium on Algorithms (ESA 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 173, pp. 55:1-55:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{garg_et_al:LIPIcs.ESA.2020.55,
  author =	{Garg, Naveen and Kumar, Nikhil},
  title =	{{Dual Half-Integrality for Uncrossable Cut Cover and Its Application to Maximum Half-Integral Flow}},
  booktitle =	{28th Annual European Symposium on Algorithms (ESA 2020)},
  pages =	{55:1--55:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-162-7},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{173},
  editor =	{Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2020.55},
  URN =		{urn:nbn:de:0030-drops-129214},
  doi =		{10.4230/LIPIcs.ESA.2020.55},
  annote =	{Keywords: Combinatorial Optimization, Multicommodity Flow, Network Design}
}
Document
Track A: Algorithms, Complexity and Games
DOI: 10.4230/LIPIcs.ICALP.2019.63
Non-Clairvoyant Precedence Constrained Scheduling

Authors: Naveen Garg, Anupam Gupta, Amit Kumar, and Sahil Singla

Published in: LIPIcs, Volume 132, 46th International Colloquium on Automata, Languages, and Programming (ICALP 2019)

Abstract
We consider the online problem of scheduling jobs on identical machines, where jobs have precedence constraints. We are interested in the demanding setting where the jobs sizes are not known up-front, but are revealed only upon completion (the non-clairvoyant setting). Such precedence-constrained scheduling problems routinely arise in map-reduce and large-scale optimization. For minimizing the total weighted completion time, we give a constant-competitive algorithm. And for total weighted flow-time, we give an O(1/epsilon^2)-competitive algorithm under (1+epsilon)-speed augmentation and a natural "no-surprises" assumption on release dates of jobs (which we show is necessary in this context). Our algorithm proceeds by assigning virtual rates to all waiting jobs, including the ones which are dependent on other uncompleted jobs. We then use these virtual rates to decide on the actual rates of minimal jobs (i.e., jobs which do not have dependencies and hence are eligible to run). Interestingly, the virtual rates are obtained by allocating time in a fair manner, using a Eisenberg-Gale-type convex program (which we can solve optimally using a primal-dual scheme). The optimality condition of this convex program allows us to show dual-fitting proofs more easily, without having to guess and hand-craft the duals. This idea of using fair virtual rates may have broader applicability in scheduling problems.
Cite as

Naveen Garg, Anupam Gupta, Amit Kumar, and Sahil Singla. Non-Clairvoyant Precedence Constrained Scheduling. In 46th International Colloquium on Automata, Languages, and Programming (ICALP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 132, pp. 63:1-63:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{garg_et_al:LIPIcs.ICALP.2019.63,
  author =	{Garg, Naveen and Gupta, Anupam and Kumar, Amit and Singla, Sahil},
  title =	{{Non-Clairvoyant Precedence Constrained Scheduling}},
  booktitle =	{46th International Colloquium on Automata, Languages, and Programming (ICALP 2019)},
  pages =	{63:1--63:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-109-2},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{132},
  editor =	{Baier, Christel and Chatzigiannakis, Ioannis and Flocchini, Paola and Leonardi, Stefano},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2019.63},
  URN =		{urn:nbn:de:0030-drops-106394},
  doi =		{10.4230/LIPIcs.ICALP.2019.63},
  annote =	{Keywords: Online algorithms, Scheduling, Primal-Dual analysis, Nash welfare}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2012.267
Approximation Algorithms for the Unsplittable Flow Problem on Paths and Trees

Authors: Khaled Elbassioni, Naveen Garg, Divya Gupta, Amit Kumar, Vishal Narula, and Arindam Pal

Published in: LIPIcs, Volume 18, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2012)

Abstract
We study the Unsplittable Flow Problem (UFP) and related variants, namely UFP with Bag Constraints and UFP with Rounds, on paths and trees. We provide improved constant factor approximation algorithms for all these problems under the no bottleneck assumption (NBA), which says that the maximum demand for any source-sink pair is at most the minimum capacity of any edge. We obtain these improved results by expressing a feasible solution to a natural LP relaxation of the UFP as a near-convex combination of feasible integral solutions.
Cite as

Khaled Elbassioni, Naveen Garg, Divya Gupta, Amit Kumar, Vishal Narula, and Arindam Pal. Approximation Algorithms for the Unsplittable Flow Problem on Paths and Trees. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2012). Leibniz International Proceedings in Informatics (LIPIcs), Volume 18, pp. 267-275, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)

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@InProceedings{elbassioni_et_al:LIPIcs.FSTTCS.2012.267,
  author =	{Elbassioni, Khaled and Garg, Naveen and Gupta, Divya and Kumar, Amit and Narula, Vishal and Pal, Arindam},
  title =	{{Approximation Algorithms for the Unsplittable Flow Problem on Paths and Trees}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2012)},
  pages =	{267--275},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-47-7},
  ISSN =	{1868-8969},
  year =	{2012},
  volume =	{18},
  editor =	{D'Souza, Deepak and Radhakrishnan, Jaikumar and Telikepalli, Kavitha},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2012.267},
  URN =		{urn:nbn:de:0030-drops-38650},
  doi =		{10.4230/LIPIcs.FSTTCS.2012.267},
  annote =	{Keywords: Approximation Algorithms, Integer Decomposition, Linear Programming, Scheduling, Unsplittable Flows}
}
Document
DOI: 10.4230/LIPIcs.FSTTCS.2011.176
Cubicity, Degeneracy, and Crossing Number

Authors: Abhijin Adiga, L. Sunil Chandran, and Rogers Mathew

Published in: LIPIcs, Volume 13, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011)

Abstract
A k-box B=(R_1,R_2,...,R_k), where each R_i is a closed interval on the real line, is defined to be the Cartesian product R_1 X R_2 X ... X R_k. If each R_i is a unit length interval, we call B a k-cube. Boxicity of a graph G, denoted as box(G), is the minimum integer k such that G is an intersection graph of k-boxes. Similarly, the cubicity of G, denoted as cub(G), is the minimum integer k such that G is an intersection graph of k-cubes. It was shown in [L. Sunil Chandran, Mathew C. Francis, and Naveen Sivadasan. Representing graphs as the intersection of axis-parallel cubes. MCDES-2008, IISc Centenary Conference, available at CoRR, abs/cs/0607092, 2006.] that, for a graph G with maximum degree \Delta, cub(G) <= \lceil 4(\Delta +1) ln n\rceil. In this paper we show that, for a k-degenerate graph G, cub(G) <= (k+2) \lceil 2e log n \rceil. Since k is at most \Delta and can be much lower, this clearly is a stronger result. We also give an efficient deterministic algorithm that runs in O(n^2k) time to output a 8k(\lceil 2.42 log n\rceil + 1) dimensional cube representation for G. The crossing number of a graph G, denoted as CR(G), is the minimum number of crossing pairs of edges, over all drawings of G in the plane. An important consequence of the above result is that if the crossing number of a graph G is t, then box(G) is O(t^{1/4}{\lceil log t\rceil}^{3/4}) . This bound is tight upto a factor of O((log t)^{3/4}). Let (P,\leq) be a partially ordered set and let G_{P} denote its underlying comparability graph. Let dim(P) denote the poset dimension of P. Another interesting consequence of our result is to show that dim(P) \leq 2(k+2) \lceil 2e \log n \rceil, where k denotes the degeneracy of G_{P}. Also, we get a deterministic algorithm that runs in O(n^2k) time to construct a 16k(\lceil 2.42 log n\rceil + 1) sized realizer for P. As far as we know, though very good upper bounds exist for poset dimension in terms of maximum degree of its underlying comparability graph, no upper bounds in terms of the degeneracy of the underlying comparability graph is seen in the literature.
Cite as

Abhijin Adiga, L. Sunil Chandran, and Rogers Mathew. Cubicity, Degeneracy, and Crossing Number. In IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011). Leibniz International Proceedings in Informatics (LIPIcs), Volume 13, pp. 176-190, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)

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@InProceedings{adiga_et_al:LIPIcs.FSTTCS.2011.176,
  author =	{Adiga, Abhijin and Chandran, L. Sunil and Mathew, Rogers},
  title =	{{Cubicity, Degeneracy, and Crossing Number}},
  booktitle =	{IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2011)},
  pages =	{176--190},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-34-7},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{13},
  editor =	{Chakraborty, Supratik and Kumar, Amit},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2011.176},
  URN =		{urn:nbn:de:0030-drops-33428},
  doi =		{10.4230/LIPIcs.FSTTCS.2011.176},
  annote =	{Keywords: Degeneracy, Cubicity, Boxicity, Crossing Number, Interval Graph, Intersection Graph, Poset Dimension, Comparability Graph}
}
Document
DOI: 10.4230/DagSemProc.08441.2
08441 Final Report – Emerging Uses and Paradigms for Dynamic Binary Translation

Authors: Erik Altman, Bruce R. Childers, Robert Cohn, Jack Davidson, Koen De Brosschere, Bjorn De Sutter, Anton M. Ertl, Michael Franz, Yuan Gu, Matthias Hauswirth, Thomas Heinz, Wei-Chung Hsu, Jens Knoop, Andreas Krall, Naveen Kumar, Jonas Maebe, Robert Muth, Xavier Rival, Erven Rohou, Roni Rosner, Mary Lou Soffa, Jens Troeger, and Christopher Vick

Published in: Dagstuhl Seminar Proceedings, Volume 8441, Emerging Uses and Paradigms for Dynamic Binary Translation (2009)

Abstract
Software designers and developers face many problems in designing, building, deploying, and maintaining cutting-edge software applications–reliability,security,performance,power,legacy code,use of multi-core platforms,and maintenance are just a few of the issues that must be considered. Many of these issues are fundamental parts of the grand challenges in computer science such as reliability and security.
Cite as

Erik Altman, Bruce R. Childers, Robert Cohn, Jack Davidson, Koen De Brosschere, Bjorn De Sutter, Anton M. Ertl, Michael Franz, Yuan Gu, Matthias Hauswirth, Thomas Heinz, Wei-Chung Hsu, Jens Knoop, Andreas Krall, Naveen Kumar, Jonas Maebe, Robert Muth, Xavier Rival, Erven Rohou, Roni Rosner, Mary Lou Soffa, Jens Troeger, and Christopher Vick. 08441 Final Report – Emerging Uses and Paradigms for Dynamic Binary Translation. In Emerging Uses and Paradigms for Dynamic Binary Translation. Dagstuhl Seminar Proceedings, Volume 8441, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{altman_et_al:DagSemProc.08441.2,
  author =	{Altman, Erik and Childers, Bruce R. and Cohn, Robert and Davidson, Jack and De Brosschere, Koen and De Sutter, Bjorn and Ertl, Anton M. and Franz, Michael and Gu, Yuan and Hauswirth, Matthias and Heinz, Thomas and Hsu, Wei-Chung and Knoop, Jens and Krall, Andreas and Kumar, Naveen and Maebe, Jonas and Muth, Robert and Rival, Xavier and Rohou, Erven and Rosner, Roni and Soffa, Mary Lou and Troeger, Jens and Vick, Christopher},
  title =	{{08441 Final Report – Emerging Uses and Paradigms for Dynamic Binary Translation}},
  booktitle =	{Emerging Uses and Paradigms for Dynamic Binary Translation},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{8441},
  editor =	{Bruce R. Childers and Jack Davidson and Koen De Bosschere and Mary Lou Soffa},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.08441.2},
  URN =		{urn:nbn:de:0030-drops-18888},
  doi =		{10.4230/DagSemProc.08441.2},
  annote =	{Keywords: Dynamic binary translation, Virtual machines}
}
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