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Improved Fixed-Parameter Algorithms for Minimum-Flip Consensus Trees

Sebastian Böcker, Quang Bao Anh Bui, Anke Truss
2012 ACM Transactions on Algorithms  
We present two fixed-parameter algorithms for the Minimum-Flip Problem, one with running time (4.83 + ( , )) and another one with running time (4.42 + ( , )) for taxa, characters, flips, and ( , ) denotes  ...  a polynomial function in and .  ...  Q.B.A Bui gratefully acknowledges financial support from the DFG, research group PABI (Parameterized Algorithms in Bioinformatics) BO 1910/5. Bibliography  ... 
doi:10.1145/2071379.2071386 fatcat:xqlujhhz6re47hnpjsmaj56xpe

Approximate Minimum Diameter [article]

Mohammad Ghodsi, Hamid Homapour, Masoud Seddighin
2017 arXiv   pre-print
In d-dimensional space, we propose a polynomial time √(d)-approximation algorithm.  ...  We present an O(2^1/ϵ^d·ϵ^-2d· n^3 ) time approximation algorithm of factor (1+ϵ) for finding minimum diameter of a set of points in d dimensions.  ...  In Section . , we present a polynomial time √ -approximation algorithm for . .  ... 
arXiv:1703.10976v1 fatcat:nnhgppapt5f3fffurfidcqdrdy

Approximability of OFDMA Scheduling [chapter]

Marcel Ochel, Berthold Vöcking
2009 Lecture Notes in Computer Science  
We prove that the problem is NP-hard and cannot be approximated with approximation factor α, unless P = NP, where α > 1 is any polynomial time computable function.  ...  We show that this maximin version of the problem admits a PTAS if all demands are identical and a 1 2 -approximation for general demands.  ...  Up to our knowledge no polynomial time approximation algorithm for Max-Rate OFDMA with a theoretical worst-case bound has been known to date.  ... 
doi:10.1007/978-3-642-04128-0_35 fatcat:tihgdgprt5dtzcebzwmftdg24e

Efficient maximum flow algorithms

Andrew V. Goldberg, Robert E. Tarjan
2014 Communications of the ACM  
A polynomial algorithm is one with a worst-case time bound polynomial in n, m, and log U.  ...  For a quarter century, there was a big gap between the unit capacity case and the general case.  ...  of 1 + ε of maximum) in undirected graphs and culminates in a near-linear time algorithm.  ... 
doi:10.1145/2628036 fatcat:chwxrnxvnfdfxeekdiyjzz2toi

Fast Semidifferential-based Submodular Function Optimization [article]

Rishabh Iyer, Stefanie Jegelka, Jeff Bilmes
2013 arXiv   pre-print
We analyze theoretical properties of our algorithms for minimization and maximization, and show that many state-of-the-art maximization algorithms are special cases.  ...  The practicality of our algorithms is important since interest in submodularity, owing to its natural and wide applicability, has recently been in ascendance within machine learning.  ...  In addition, it may be viewed as a special case of a proximal minimization algorithm that uses Bregman Acknowledgments: We thank Karthik Mohan, John Halloran and Kai Wei for discussions.  ... 
arXiv:1308.1006v1 fatcat:zyenz2okerbstmjyqkl43azsy4

Efficient reduction of L-infinity geometry problems

Hongdong Li
2009 2009 IEEE Conference on Computer Vision and Pattern Recognition  
This paper presents a new method for computing optimal L∞ solutions for vision geometry problems, particularly for those problems of fixed-dimension and of large-scale.  ...  By using the fact that many of the problems in question are pseudoconvex, we prove that such a reduction is possible.  ...  We would like to thank Carl Olsson (Lund) for his invaluable remarks and for the simplified proof of the main reduction theorem. The research is supported in part by CRL NICTA (the VIBE project).  ... 
doi:10.1109/cvprw.2009.5206653 fatcat:uoimaqwxhbcq3myukw7zizqmaa

Efficient reduction of L-infinity geometry problems

Hongdong Li
2009 2009 IEEE Conference on Computer Vision and Pattern Recognition  
This paper presents a new method for computing optimal L∞ solutions for vision geometry problems, particularly for those problems of fixed-dimension and of large-scale.  ...  By using the fact that many of the problems in question are pseudoconvex, we prove that such a reduction is possible.  ...  We would like to thank Carl Olsson (Lund) for his invaluable remarks and for the simplified proof of the main reduction theorem. The research is supported in part by CRL NICTA (the VIBE project).  ... 
doi:10.1109/cvpr.2009.5206653 dblp:conf/cvpr/Li09 fatcat:2ijjbyvhcbhlvjofjt66hsdgaa

Complexity and Intractability: Limitations to Implementation in Analytical Cartography

Alan Saalfeld
2000 Cartography and Geographic Information Science  
The computational complexity of algorithms is an important consideration for all computer systems, including geographic information systems and mapping systems.  ...  Mathematical cartographers and GIS professionals need to understand and to take into account the limitations imposed on problem-solving by the very nature of computation itself.  ...  For example, some problems involving graphs are NP-complete, but can be solved in the special case of trees in polynomial time. 2.  ... 
doi:10.1559/152304000783547849 fatcat:pf6nayh4lvfipo7uzaq4jndury

In Search of the Densest Subgraph

András Faragó, Zohre R. Mojaveri
2019 Algorithms  
While this problem has been the subject of active research for over half of a century, with many proposed variants and solutions, new results still continuously emerge in the literature.  ...  Our goal is motivated by the fact that, in many applications, it is a key algorithmic task to extract a densest subgraph from an input graph, according to some appropriate definition of graph density.  ...  For example, we see that the density measure ∑ x d 2 S (x) |V(S)| can be optimized in polynomial time, as a special case of the F-density.  ... 
doi:10.3390/a12080157 fatcat:7rht55sor5errh2zkyvildkmhi

Deterministic risk control for cost-effective network connections

Eduardo Álvarez-Miranda, Xujin Chen, Jie Hu, Xiaodong Hu, Alfredo Candia-Véjar
2011 Theoretical Computer Science  
We develop polynomial time algorithms for minimum cost network connection with paths or spanning trees under risk-sum constraints.  ...  This paper considers the minimum connection problem in networks with uncertain data.  ...  Eduardo Álvarez-Miranda was supported in part by Dirección de Programas de Investigación, Universidad de Talca, Chile, and P 4 Project Grant ''Center for Research and Applications in Plasma Physics and  ... 
doi:10.1016/j.tcs.2009.08.019 fatcat:sjuktdqiabca3fvr5wsppa3iha

Allocation of bandwidth and storage

BO CHEN, REFAEL HASSIN, MICHAL TZUR
2002 IIE Transactions  
In this paper we provide polynomial-time algorithms for solving various special cases, and develop polynomial-time approximation algorithms for very general NP-hard cases with good performance guarantees  ...  In these problems, we face a number of independent requests, respectively, for reservation of bandwidth of a communication channel of fixed capacity and for storage of items into a space of fixed size.  ...  Acknowledgement Bo Chen gratefully acknowledges the partial support he received via a ESRC Management Research Fellowship and the support of the Academic Study Group.  ... 
doi:10.1080/07408170208928886 fatcat:xaywkihfgjfelll3j6nfcjwhie

Characterizing achievable multicast rates in multi-hop wireless networks

Randeep Bhatia, Li (Erran) Li
2005 Proceedings of the 6th ACM international symposium on Mobile ad hoc networking and computing - MobiHoc '05  
We consider the fundamental constraint that a node can not be involved in multiple communications at the same time.  ...  In the single multicast tree case, (1) for the unicast model, we show that the problem is NP-hard and it is not approximable to a factor better than 1.5; we then give a 1.5-approximation algorithm if all  ...  Note that this algorithm is the best possible polynomial time algorithm in terms of estimating the worst case throughput.  ... 
doi:10.1145/1062689.1062708 dblp:conf/mobihoc/BhatiaL05 fatcat:c4dyf6w475gvjkh2p23h5bvhta

Algorithms and analysis of scheduling for low-power high-performance DSP on VLIW processors

Zili Shao, Qingfeng Zhuge, Youtao Zhang, Edwin H-M. Sha
2004 International Journal of High Performance Computing and Networking  
The experimental results show that EMSA gives a ¢ ¤ £ ¦ ¥ § % reduction in energy compared with the traditional list scheduling approach on average. analyze and design efficient algorithms for various  ...  We first formally prove that this problem is NP-complete. Then three heuristic algorithms, MSAS, MLMSA, and EMSA, are proposed.  ...  Two algorithms for two special cases are presented first and then another algorithm to solve general problem is proposed. A.  ... 
doi:10.1504/ijhpcn.2004.007561 fatcat:xrqfz5qdpncpzhl6qgw4k7usbu

Experimental Evaluation of Parameterized Algorithms for Feedback Vertex Set [article]

Krzysztof Kiljan, Marcin Pilipczuk
2018 arXiv   pre-print
Feedback Vertex Set is a classic combinatorial optimization problem that asks for a minimum set of vertices in a given graph whose deletion makes the graph acyclic.  ...  From the point of view of parameterized algorithms and fixed-parameter tractability, Feedback Vertex Set is one of the landmark problems: a long line of study resulted in multiple algorithmic approaches  ...  In the case of Feedback Vertex Set, [21] shows that the following local problem has a polynomial-time solvable half-integral relaxation: given a root vertex s ∈ V (G), find a minimum-size set X ⊆ V (  ... 
arXiv:1803.00925v2 fatcat:rvz7oejyufbjxiwyce43vhqygi

Efficient Computations of a Security Index for False Data Attacks in Power Networks [article]

Julien M. Hendrickx, Karl Henrik Johansson, Raphael M. Jungers, Henrik Sandberg, Kin Cheong Sou
2013 arXiv   pre-print
In such cases, we show indeed that the problem can be cast as a generalization of the minimum cut problem involving costly nodes.  ...  The vulnerability analysis problem is shown to be NP-hard, meaning that unless P = NP there is no polynomial time algorithm to analyze the vulnerability of the system.  ...  problem in this paper is not a special case of the ones in [11] , [14] .  ... 
arXiv:1204.6174v2 fatcat:7ndx35ldfbgwfav2whjd3unwam
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