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Feedback arc set

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2322:, and the Hamiltonian paths correspond one-for-one with minimal feedback arc sets, disjoint from the corresponding path. The Hamiltonian path for a feedback arc set is found by reversing its arcs and finding a topological order of the resulting acyclic tournament. Every consecutive pair of the order must be disjoint from the feedback arc sets, because otherwise one could find a smaller feedback arc set by reversing that pair. Therefore, this ordering gives a path through arcs of the original tournament, covering all vertices. Conversely, from any Hamiltonian path, the set of edges that connect later vertices in the path to earlier ones forms a feedback arc set. It is minimal, because each of its edges belongs to a cycle with the Hamiltonian path edges that is disjoint from all other such cycles. In a tournament, it may be the case that the minimum feedback arc set and maximum acyclic subgraph are both close to half the edges. More precisely, every tournament graph has a feedback arc set of size 302:, the vertices of a given directed graph are partitioned into an ordered sequence of subsets (the layers of the drawing), and each subset is placed along a horizontal line of this drawing, with the edges extending upwards and downwards between these layers. In this type of drawing, it is desirable for most or all of the edges to be oriented consistently downwards, rather than mixing upwards and downwards edges, in order for the reachability relations in the drawing to be more visually apparent. This is achieved by finding a minimum or minimal feedback arc set, reversing the edges in that set, and then choosing the partition into layers in a way that is consistent with a topological order of the resulting acyclic graph. Feedback arc sets have also been used for a different subproblem of layered graph drawing, the ordering of vertices within consecutive pairs of layers. 172: 1891: 179:, pool F, and the minimum-upset ranking for these scores. Arrows are directed from the loser to the winner of each match, and are colored blue when the outcome is consistent with the ranking and red for an upset, an outcome inconsistent with the ranking. With this ranking, only one match is an upset, the one in which USA beat QAT. The actual ranking used in the Olympics differed by placing ESP ahead of QAT on set ratio, causing their match to be ranked as another upset. 203:, the outcomes of each game can be recorded by directing an edge from the loser to the winner of each game. Finding a minimum feedback arc set in the resulting graph, reversing its edges, and topological ordering, produces a ranking on all of the competitors. Among all of the different ways of choosing a ranking, it minimizes the total number of upsets, games in which a lower-ranked competitor beat a higher-ranked competitor. Many sports use simpler methods for 229:, it is of interest to determine subjects' rankings of sets of objects according to a given criterion, such as their preference or their perception of size, based on pairwise comparisons between all pairs of objects. The minimum feedback arc set in a tournament graph provides a ranking that disagrees with as few pairwise outcomes as possible. Alternatively, if these comparisons result in independent probabilities for each pairwise ordering, then the 33: 498: 313:, the problem of removing the smallest number of dependencies to break a deadlock can be modeled as one of finding a minimum feedback arc set. However, because of the computational difficulty of finding this set, and the need for speed within operating system components, heuristics rather than exact algorithms are often used in this application. 1898:
of Karp and Lawler, from vertex cover of the large yellow graph to minimum feedback arc set in the small blue graph, expands each yellow vertex into two adjacent blue graph vertices, and each undirected yellow edge into two opposite directed edges. The minimum vertex cover (upper left and lower right
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of the other. However, for parameterized complexity and approximation, they differ, because the analysis used for those kinds of algorithms depends on the size of the solution and not just on the size of the input graph, and the minimum feedback arc set and maximum acyclic subgraph have different
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by splitting them at articulation vertices. The choice of solution within any one of these subproblems does not affect the others, and the edges that do not appear in any of these components are useless for inclusion in the feedback arc set. When one of these components can be separated into two
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into two vertices, one for incoming edges and one for outgoing edges. These transformations allow exact algorithms for feedback arc sets and for feedback vertex sets to be converted into each other, with an appropriate translation of their complexity bounds. However, this transformation does not
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are another class of directed graphs on which the feedback arc set problem may be solved in polynomial time. These graphs describe the flow of control in structured programs for many programming languages. Although structured programs often produce planar directed flow graphs, the definition of
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can be described as seeking an ordering that minimizes the sum, over pairs of candidates, of the number of voters who prefer the opposite ordering for that pair. This can be formulated and solved as a minimum-weight feedback arc set problem, in which the vertices represent candidates, edges are
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circuits, in which signals can propagate in cycles through the circuit instead of always progressing from inputs to outputs. In such circuits, a minimum feedback arc set characterizes the number of points at which amplification is necessary to allow the signals to propagate without loss of
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on a feedback arc set, and guessing or trying all possibilities for the values on those edges, allows the rest of the process to be analyzed in a systematic way because of its acyclicity. In this application, the idea of breaking edges in this way is called "tearing".
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to choose the ordering. This algorithm finds and deletes a vertex whose numbers of incoming and outgoing edges are as far apart as possible, recursively orders the remaining graph, and then places the deleted vertex at one end of the resulting order. For graphs with
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This means that the size of the feedback arc set that it finds is at most this factor larger than the optimum. Determining whether feedback arc set has a constant-ratio approximation algorithm, or whether a non-constant ratio is necessary, remains an open problem.
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are also used. If a feedback arc set is minimal, meaning that removing any edge from it produces a subset that is not a feedback arc set, then it has an additional property: reversing all of its edges, rather than removing them, produces a directed acyclic graph.
2282:: the minimum size of a feedback arc set equals the maximum number of edge-disjoint directed cycles that can be found in the graph. This is not true for some other graphs; for instance the first illustration shows a directed version of the non-planar graph 4094:
Bonamy, Marthe; Kowalik, Lukasz; Nederlof, Jesper; Pilipczuk, Michal; Socala, Arkadiusz; Wrochna, Marcin (2018), "On directed feedback vertex set parameterized by treewidth", in Brandstädt, Andreas; Köhler, Ekkehard; Meer, Klaus (eds.),
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from vertex cover to feedback arc set, which preserves the quality of approximations. By a different reduction, the maximum acyclic subgraph problem is also APX-hard, and NP-hard to approximate to within a factor of 65/66 of optimal.
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Some NP-complete problems can become easier when their inputs are restricted to special cases. But for the most important special case of the feedback arc set problem, the case of tournaments, the problem remains NP-complete.
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made from asynchronous components, synchronization can be achieved by placing clocked gates on the edges of a feedback arc set. Additionally, cutting a circuit on a feedback arc a set reduces the remaining circuit to
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One way to find the minimum feedback arc set is to search for an ordering of the vertices such that as few edges as possible are directed from later vertices to earlier vertices in the ordering. Searching all
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is true, then the minimum feedback arc set problem is hard to approximate in polynomial time to within any constant factor, and the maximum feedback arc set problem is hard to approximate to within a factor
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Hanauer, Kathrin; Brandenburg, Franz-Josef; Auer, Christopher (2013), "Tight upper bounds for minimum feedback arc sets of regular graphs", in Brandstädt, Andreas; Jansen, Klaus; Reischuk, Rüdiger (eds.),
1523: 1857:, which generalizes to a weighted version of the problem. A subexponential parameterized algorithm for weighted feedback arc sets on tournaments is also known. The maximum acyclic subgraph problem for 1826:, using the fact that the triconnected components of these graphs are either planar or of bounded size. Planar graphs have also been generalized in a different way to a class of directed graphs called 264:
directed to represent the winner of each head-to-head contest, and the cost of each edge represents the number of voters who would be made unhappy by giving a higher ranking to the head-to-head loser.
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Instead of minimizing the size of the feedback arc set, researchers have also looked at minimizing the maximum number of edges removed from any vertex. This variation of the problem can be solved in
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Here, a feedback vertex set is defined analogously to a feedback arc set, as a subset of the vertices of the graph whose deletion would eliminate all cycles. The line graph of a directed graph
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Partition the edges into two acyclic subgraphs, one consisting of the edges directed consistently with the ordering, and the other consisting of edges directed oppositely to the ordering.
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of the underlying undirected graph. The circuit rank is an undirected analogue of the feedback arc set, the minimum number of edges that need to be removed from a graph to reduce it to a
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Estep, D.Q.; Crowell-Davis, S.L.; Earl-Costello, S.-A.; Beatey, S.A. (January 1993), "Changes in the social behaviour of drafthorse (Equus caballus) mares coincident with foaling",
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is a subset of the edges of the graph that contains at least one edge out of every cycle in the graph. Removing these edges from the graph breaks all of the cycles, producing an
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to the minimum feedback arc set, it is necessary to modify the problem from being an optimization problem (how few edges can be removed to break all cycles) to an equivalent
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Other parameters than the natural parameter have also been studied. A fixed-parameter tractable algorithm using dynamic programming can find minimum feedback arc sets in
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are often determined by searching for an ordering with the fewest reversals in observed dominance behavior, another form of the minimum feedback arc set problem.
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disconnected subgraphs by removing two vertices, a more complicated decomposition applies, allowing the problem to be split into subproblems derived from the
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Chen, Jianer; Liu, Yang; Lu, Songjian; O'Sullivan, Barry; Razgon, Igor (2008), "A fixed-parameter algorithm for the directed feedback vertex set problem",
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by transforming it into an equivalent feedback vertex set problem and applying a parameterized feedback vertex set algorithm. Because the exponent of
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dynamic programming on a tree decomposition of the graph can find the minimum feedback arc set in time polynomial in the graph size and exponential
128:, and maximum acyclic subgraphs can be approximated to within a constant factor. Both are hard to approximate closer than some constant factor, an 5613: 3276: 2888: 3309:; published in preliminary form as ASTIA Document No. AD 206 573, United States Air Force, Office of Scientific Research, November 1958, 1605:. This dual problem is polynomially solvable, and therefore the planar minimum feedback arc set problem is as well. It can be solved in 4297: 4730: 252:
of arranging elements into a linear ordering, in cases where data is available that provides pairwise comparisons between the elements.
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Graph-Theoretic Concepts in Computer Science - 39th International Workshop, WG 2013, Lübeck, Germany, June 19-21, 2013, Revised Papers
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Mishra, Sounaka; Sikdar, Kripasindhu (2004), "On approximability of linear ordering and related NP-optimization problems on graphs",
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Graph-Theoretic Concepts in Computer Science - 44th International Workshop, WG 2018, Cottbus, Germany, June 27-29, 2018, Proceedings
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Algorithms and Computation - 21st International Symposium, ISAAC 2010, Jeju Island, Korea, December 15-17, 2010, Proceedings, Part I
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Partition of a directed graph into a minimum feedback arc set (red dashed edges) and a maximum acyclic subgraph (blue solid edges)
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is the unique minimum feedback arc set of the tournament. The size of this tournament has been defined as the "reversing number"
5000: 4792: 3545: 3094:; Fleischer, Lisa K.; Rurda, Atri (2010), "Ordering by weighted number of wins gives a good ranking for weighted tournaments", 2315:
in which the minimum size of a feedback arc set is two, while the maximum number of edge-disjoint directed cycles is only one.
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is defined as consisting of optimization problems that have a polynomial time approximation algorithm that achieves a constant
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The minimum feedback arc set and maximum acyclic subgraph are equivalent for the purposes of exact optimization, as one is the
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Feehrer, John R.; Jordan, Harry F. (December 1995), "Placement of clock gates in time-of-flight optoelectronic circuits",
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that tests all partitions of the vertices into two equal subsets and recurses within each subset can solve the problem in
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can be obtained from the solution to a minimum feedback arc set problem on a graph obtained by splitting every vertex of
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based on points awarded for each game; these methods can provide a constant approximation to the minimum-upset ranking.
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In both exact and approximate solutions to the feedback arc set problem, it is sufficient to solve separately each
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Fernandez de la Vega, W. (1983), "On the maximum cardinality of a consistent set of arcs in a random tournament",
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Proceedings of the 39th Annual ACM Symposium on Theory of Computing, San Diego, California, USA, June 11-13, 2007
3051: 204: 4689:; Schudy, Warren (2007), "How to rank with few errors: a PTAS for weighted feedback arc set on tournaments", in 4151: 3858:
Park, S.; Akers, S.B. (1992), "An efficient method for finding a minimal feedback arc set in directed graphs",
3472:, Technical reports, vol. 320, Massachusetts Institute of Technology, Research Laboratory of Electronics, 3096: 2223: 5087:
Proceedings of the 34th Annual ACM Symposium on Theory of Computing, May 19-21, 2002, Montréal, Québec, Canada
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Nutov, Zeev; Penn, Michal (2000), "On integrality, stability and composition of dicycle packings and covers",
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edges). Thus, the decision version of the feedback arc set problem takes as input both a directed graph and a
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The maximum acyclic subgraph problem has an easy approximation algorithm that achieves an approximation ratio
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Schwikowski, Benno; Speckenmeyer, Ewald (2002), "On enumerating all minimal solutions of feedback problems",
1866: 230: 151:, is a set of vertices containing at least one vertex from every cycle in a directed or undirected graph. In 5413: 4819:, Proc. Sympos. IBM Thomas J. Watson Res. Center, Yorktown Heights, N.Y., New York: Plenum, pp. 85–103 4755:"A new rounding procedure for the assignment problem with applications to dense graph arrangement problems" 4187: 3775: 3015: 670: 534: 502: 2767:
There are infinitely many Eulerian directed graphs for which this bound is tight. If a directed graph has
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Several problems involving finding rankings or orderings can be solved by finding a feedback arc set on a
3814: 2155: 1077: 926: 306: 89: 4954:; D'Atri, A.; Protasi, M. (1980), "Structure preserving reductions among convex optimization problems", 4556:
34th Annual Symposium on Foundations of Computer Science, Palo Alto, California, USA, 3-5 November 1993
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Hassin, Refael; Rubinstein, Shlomi (1994), "Approximations for the maximum acyclic subgraph problem",
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Bastert, Oliver; Matuszewski, Christian (2001), "Layered drawings of digraphs", in Kaufmann, Michael;
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The best known polynomial-time approximation algorithm for the feedback arc set has the non-constant
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are the largest acyclic subgraphs, and the number of edges removed in forming a spanning tree is the
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Bonnet, Édouard; Paschos, Vangelis Th. (2018), "Sparsification and subexponential approximation",
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Demetrescu, Camil; Finocchi, Irene (2001), "Break the "right" cycles and get the "best" drawing",
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Remage, Russell Jr.; Thompson, W. A. Jr. (1966), "Maximum-likelihood paired comparison rankings",
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Another, more complicated, polynomial time approximation algorithm applies to graphs with maximum
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of the given graph, and to break these strongly connected components down even farther to their
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vertices, with at most three edges per vertex, then it has a feedback arc set of at most
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and each vertex has equal numbers of incoming and outgoing edges. For such a graph, with
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Proceedings of the 1992 IEEE International Symposium on Circuits and Systems (ISCAS '92)
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Seyfarth, Robert M. (November 1976), "Social relationships among adult female baboons",
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can be used as the desired ranking. Applications of this method include the following:
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and among directed acyclic graphs with the same number of vertices it is largest when
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that are standard in computational complexity theory but stronger than P ≠ NP. If the
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Thompson, W. A. Jr.; Remage, Russell Jr. (1964), "Rankings from paired comparisons",
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edges, with at most four edges per vertex, then it has a feedback arc set of at most
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The hardness of approximation of these problems has also been studied under unproven
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Vaziri, Baback; Dabadghao, Shaunak; Yih, Yuehwern; Morin, Thomas L. (January 2018),
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Lucchesi, C. L.; Younger, D. H. (1978), "A minimax theorem for directed graphs",
4486: 4444: 4424: 4375: 4341: 4289: 4229: 4206: 4168: 4033: 3918: 3792: 3748: 3699: 3673: 3646: 3602: 3408: 3357: 3301: 3125: 3113: 3091: 3032: 2988: 2939: 2917: 2279: 2025: 1904: 1870: 121: 45: 5129: 5053: 4605:; Jünger, Michael; Reinelt, Gerhard (1985), "On the acyclic subgraph polytope", 4554:(1993), "A framework for cost-scaling algorithms for submodular flow problems", 4464: 4114: 4099:, Lecture Notes in Computer Science, vol. 11159, Springer, pp. 65–78, 3680:(1998), "Approximating minimum feedback sets and multicuts in directed graphs", 3434: 3274:
Brunk, H. D. (1960), "Mathematical models for ranking from paired comparisons",
3253: 2976: 1008:; it is much easier to compute than the minimum feedback arc set. For graphs of 5133: 4750: 4722: 4686: 4527: 3412: 3374: 3238:
Slater, Patrick (1961), "Inconsistencies in a schedule of paired comparisons",
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Goddard, Stephen T. (1983), "Ranking in tournaments and group decisionmaking",
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can be embedded as a subgraph of a larger tournament graph, in such a way that
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of the overall ranking can be obtained by converting these probabilities into
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also has a polynomial-time approximation scheme. Its main ideas are to apply
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the minimum feedback arc set does not have an approximation within a factor
140:, the minimum feedback arc set can be approximated more accurately, and for 5326: 5078: 5027: 4440: 4337: 4146: 3682: 3519: 1786:
These planar algorithms can be extended to the graphs that do not have the
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Eickwort, George C. (April 2019), "Dominance in a cockroach (Nauphoeta)",
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edges, or equivalently whether there is an acyclic subgraph with at least
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and finding a minimum-weight feedback arc set in the resulting tournament.
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preserve approximation quality for the maximum acyclic subgraph problem.
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In the other direction, the minimum feedback vertex set of a given graph
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Another early application of feedback arc sets concerned the design of
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Computers and Intractability: A Guide to the Theory of NP-Completeness
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Younger, D. (1963), "Minimum feedback arc sets for a directed graph",
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vertices, the size of a minimum feedback arc set is always at least
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edges, and some graphs require this many. If a directed graph has
4904:"The minimum feedback arc set problem is NP-hard for tournaments" 4324:(1997), "Tight bounds for the maximum acyclic subgraph problem", 4270:"A fast and effective heuristic for the feedback arc set problem" 4227: 2065: 1899:
yellow vertices) corresponds to the red minimum feedback arc set.
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In planar directed graphs, the feedback arc set problem obeys a
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Hecht, Michael (2017), "Exact localisations of feedback sets",
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It asks whether all cycles can be broken by removing at most
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or when the weights are positive integers that are at most a
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Beyond polynomial time for approximation algorithms, if the
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is the size of the minimum feedback arc set. On graphs with
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On the Approximability of NP-complete Optimization Problems
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When the minimum feedback arc set problem is restricted to
4399:(Master's thesis), Massachusetts Institute of Technology, 2923:
British Journal of Mathematical and Statistical Psychology
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Minoura, Toshimi (1982), "Deadlock avoidance revisited",
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Graph Drawing: Algorithms for the Visualization of Graphs
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Feedback arc sets have applications in circuit analysis,
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Charbit, Pierre; Thomassé, Stéphan; Yeo, Anders (2007),
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Crescenzi, Pierluigi; Kann, Viggo; Halldórsson, Magnús;
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this algorithm is said to be fixed-parameter tractable.
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both problems can be solved exactly in polynomial time.
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Barthélémy, Jean-Pierre; Hudry, Olivier; Isaak, Garth;
5032:"On the hardness of approximating minimum vertex cover" 4184: 4057: 3049: 5550: 4601: 2499: 2413: 2331: 2219:
that can be computed in the subexponential time bound
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reducibility does not require the graph to be planar.
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by showing that inputs for another hard problem, the
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edges, in linear time, giving an approximation ratio
1296: 1276: 1256: 1207: 1149: 1086: 1042: 1018: 986: 929: 902: 878: 856: 792: 768: 746: 681: 634: 590: 566: 511: 479: 459: 437: 413: 391: 369: 340: 240:
The same maximum-likelihood ordering can be used for
5370: 5329:(1980), "Optimally ranking unrankable tournaments", 4685: 4467:(1981), "How to make a digraph strongly connected", 1911:, with a yes or no answer (is it possible to remove 3532:Rosen, Edward M.; Henley, Ernest J. (Summer 1968), 2395:{\displaystyle {\tbinom {n}{2}}/2-\Omega (n^{3/2})} 1662:A weighted version of the problem can be solved in 4901: 3972:(1964), "A comment on minimum feedback arc sets", 3636: 3600: 3403: 3401: 2855: 2827: 2807: 2779: 2757: 2696: 2676: 2645: 2623: 2601: 2581: 2556: 2476: 2394: 2307: 2261: 2211: 2176: 2144: 2114: 2012: 1967: 1945: 1923: 1814: 1776: 1716: 1692: 1652: 1573: 1545: 1517: 1459: 1402: 1378: 1324: 1282: 1262: 1222: 1185: 1092: 1066: 1024: 992: 970: 908: 884: 862: 840: 774: 752: 715: 659: 608: 572: 517: 485: 465: 443: 419: 397: 375: 346: 4745: 3470:A study of asynchronous logical feedback networks 1290:vertices, this produces an acyclic subgraph with 5590: 4357: 1836:polytope associated with their feedback arc sets 1597:to the problem of contracting a set of edges (a 1460:{\displaystyle m/2+\Omega (m/{\sqrt {\Delta }})} 4513: 3407: 3398: 3277:Journal of the American Statistical Association 1120: 3327: 2960: 2557:{\displaystyle {\tbinom {n}{2}}/2-1.73n^{3/2}} 784:the feedback arc set problem can be solved in 5192: 5081:(2002), "The importance of being biased", in 4679: 4264: 4223: 4221: 4219: 3489: 2515: 2502: 2477:{\displaystyle {\tbinom {n}{2}}/2-O(n^{3/2})} 2429: 2416: 2347: 2334: 2032:; its NP-completeness was proved by Karp and 669:also using an exponential amount of space. A 5446: 5248:(1976), "On two minimax theorems in graph", 5132:; Manokaran, Rajsekar; Raghavendra, Prasad; 4829: 4648: 4642: 3772: 3377:(Fall 1959), "Mathematics without numbers", 2212:{\displaystyle {\tfrac {7}{6}}-\varepsilon } 2115:{\displaystyle {\tfrac {1}{2}}+\varepsilon } 1467:edges, giving an approximation ratio of the 1379:{\displaystyle {\tfrac {1}{2}}+\Omega (n/m)} 5285: 4558:, IEEE Computer Society, pp. 449–458, 3531: 3059:Journal of the Operational Research Society 177:men's beach volleyball at the 2016 Olympics 5073: 5022: 4516:Journal of the London Mathematical Society 4397:Approximating the maximum acyclic subgraph 4316: 4216: 3722: 3720: 2863:edges, and some graphs require this many. 1126:Does the feedback arc set problem have an 132:result that can be strengthened under the 96:, ranking competitors in sporting events, 5520: 5502: 5447:Isaak, Garth; Narayan, Darren A. (2004), 5384: 5263: 5206: 5052: 4390: 4388: 4200: 4104: 4027: 3900: 3857: 3827: 3742: 3424: 3415:; Chwa, Kyung-Yong; Park, Kunsoo (eds.), 3343: 3165: 2262:{\displaystyle O(2^{n^{1-\varepsilon }})} 1235:Fix an arbitrary ordering of the vertices 5491:Combinatorics, Probability and Computing 4911:Combinatorics, Probability and Computing 4546: 4544: 4459: 4457: 4419: 4417: 4242:A compendium of NP optimization problems 4144: 3998: 3996: 3807: 3805: 3639:ACM Journal of Experimental Algorithmics 3463: 3461: 3197: 3191: 3137: 2912: 2910: 2908: 1889: 496: 170: 31: 5325: 5319: 4957:Journal of Computer and System Sciences 4509: 4507: 4149:(1989), "Fair edge deletion problems", 3942: 3936: 3896: 3894: 3726: 3717: 3663: 3661: 3659: 3131: 3012: 2889:Fédération Internationale de Volleyball 1873:the resulting algorithm using walks on 1241:Return the larger of the two subgraphs. 1134:(more unsolved problems in mathematics) 14: 5614:Computational problems in graph theory 5591: 5244: 5238: 4394: 4385: 4087: 3968: 3962: 3766: 3558: 3373: 3367: 3237: 3231: 3052:"Properties of sports ranking methods" 3006: 2956: 2954: 2952: 2916: 546:of its strongly connected components. 5478: 5400: 5118: 4944: 4739: 4595: 4550: 4541: 4463: 4454: 4423: 4414: 4051: 3993: 3903:Journal of Combinatorial Optimization 3811: 3802: 3483: 3467: 3458: 3273: 3267: 2905: 5485:Huang, Hao; Ma, Jie; Shapira, Asaf; 5440: 5364: 5293:SIAM Journal on Discrete Mathematics 5279: 5186: 5016: 4989: 4983: 4869:SIAM Journal on Discrete Mathematics 4862: 4856: 4823: 4811: 4805: 4504: 4351: 4310: 4268:; Lin, Xuemin; Smyth, W. F. (1993), 4178: 4138: 3891: 3851: 3656: 3630: 3594: 3525: 3468:Unger, Stephen H. (April 26, 1957), 3321: 2047: 1855:polynomial-time approximation scheme 1584: 1186:{\displaystyle O(\log n\log \log n)} 1130:with a constant approximation ratio? 841:{\displaystyle O(n^{4}4^{k}k^{3}k!)} 716:{\displaystyle O(4^{n}/{\sqrt {n}})} 626:can find the optimal permutation in 334:A feedback arc set of a given graph 29:Edges that hit all cycles in a graph 5544: 4895: 4817:Complexity of Computer Computations 4258: 3975:IEEE Transactions on Circuit Theory 3945:IEEE Transactions on Circuit Theory 3862:, vol. 4, pp. 1863–1866, 3043: 2949: 2873: 2653:is itself an (acyclic) tournament. 1412:and finds an acyclic subgraph with 971:{\displaystyle O(2^{r}m^{4}\log m)} 429:and an edge for each two-edge path 64:of the given graph, often called a 24: 3607:Drawing Graphs: Methods and Models 3084: 2936:10.1111/j.2044-8317.1976.tb00701.x 2506: 2490:tournaments, the size is at least 2420: 2404:and some tournaments require size 2365: 2338: 2078:computational hardness assumptions 1593:, the feedback arc set problem is 1534: 1507: 1491: 1449: 1433: 1397: 1356: 25: 5625: 3331:Annals of Mathematical Statistics 2758:{\displaystyle (m^{2}+mn)/2n^{2}} 2177:{\displaystyle \varepsilon >0} 2145:{\displaystyle \varepsilon >0} 1777:{\displaystyle O(n^{5/2}\log nN)} 3174:Applied Animal Behaviour Science 1903:In order to apply the theory of 1653:{\displaystyle O(n^{5/2}\log n)} 1245:This can be improved by using a 205:group tournament ranking systems 5373:Journal of Combinatorial Theory 5331:Periodica Mathematica Hungarica 5251:Journal of Combinatorial Theory 5176:from the original on 2021-07-31 5064:from the original on 2009-09-20 5006:from the original on 2010-12-29 4866:(2006), "Ranking tournaments", 4795:from the original on 2021-08-03 4300:from the original on 2020-10-22 4248:from the original on 2021-07-29 3548:from the original on 2021-08-02 3202:, CRC Press, pp. 120–126, 2895:from the original on 2016-12-23 1223:{\displaystyle {\tfrac {1}{2}}} 1121:Unsolved problem in mathematics 321: 166: 147:A closely related problem, the 5453:Information Processing Letters 4360:Information Processing Letters 4274:Information Processing Letters 4152:IEEE Transactions on Computers 3538:Chemical Engineering Education 3097:ACM Transactions on Algorithms 2734: 2712: 2471: 2450: 2389: 2368: 2256: 2230: 2000: 1996: 1990: 1983: 1885: 1771: 1738: 1687: 1674: 1647: 1617: 1601:) to make the resulting graph 1512: 1494: 1454: 1436: 1373: 1359: 1180: 1153: 1114: 1061: 1046: 965: 933: 835: 796: 710: 685: 654: 638: 603: 594: 199:In sporting competitions with 112:; it can be solved exactly in 13: 1: 4843:, W.H. Freeman, p. 192, 4395:Newman, Alantha (June 2000), 4202:10.1016/S0166-218X(00)00339-5 3789:10.1016/S0166-218X(03)00444-X 3152:10.1016/s0003-3472(76)80022-x 2866: 2318:Every tournament graph has a 1867:linear programming relaxation 503:strongly connected components 316: 231:maximum likelihood estimation 76:; weighted versions of these 5562:10.1007/978-3-642-45043-3_26 5427:10.1016/0166-218X(94)00042-C 5414:Discrete Applied Mathematics 5386:10.1016/0095-8956(83)90060-6 5265:10.1016/0095-8956(76)90049-6 4970:10.1016/0022-0000(80)90046-X 4666:10.1016/0196-6774(88)90022-3 4372:10.1016/0020-0190(94)00086-7 4286:10.1016/0020-0190(93)90079-O 4188:Discrete Applied Mathematics 3776:Discrete Applied Mathematics 3186:10.1016/0168-1591(93)90137-e 671:divide-and-conquer algorithm 535:strongly connected component 501:A directed graph with three 7: 5054:10.4007/annals.2005.162.439 4115:10.1007/978-3-030-00256-5_6 4008:Theory of Computing Systems 3815:Theory of Computing Systems 3435:10.1007/978-3-642-17517-6_3 2156:exponential time hypothesis 1880: 1078:exponential time hypothesis 405:has a vertex for each edge 10: 5630: 4238:"Minimum Feedback Arc Set" 1553:, the approximation ratio 1080:, no better dependence on 1067:{\displaystyle O(t\log t)} 5513:10.1017/S0963548313000394 5465:10.1016/j.ipl.2004.07.001 5217:10.1007/s00236-016-0281-2 5146:SIAM Journal on Computing 5072:; preliminary version in 4923:10.1017/S0963548306007887 4728:author's extended version 4020:10.1007/s00224-011-9312-0 3868:10.1109/iscas.1992.230449 3838:10.1007/s00224-017-9777-6 3254:10.1093/biomet/48.3-4.303 3071:10.1057/s41274-017-0266-8 2977:10.1093/biomet/53.1-2.143 2273: 1896:NP-completeness reduction 1546:{\displaystyle \Delta =3} 870:in this algorithm is the 660:{\displaystyle O(n2^{n})} 250:exploratory data analysis 118:fixed-parameter tractable 72:and its removal leaves a 4760:Mathematical Programming 4608:Mathematical Programming 4564:10.1109/SFCS.1993.366842 4528:10.1112/jlms/s2-17.3.369 3988:10.1109/tct.1964.1082291 3957:10.1109/tct.1963.1082116 3208:10.1201/9780429049262-18 2656:A directed graph has an 2158:is true, then for every 2013:{\displaystyle |E(G)|-k} 1693:{\displaystyle O(n^{3})} 734:parameterized complexity 549: 74:maximum acyclic subgraph 70:minimum feedback arc set 18:Minimum feedback arc set 4753:; Kaplan, Haim (2002), 4707:10.1145/1250790.1250806 4410:Guruswami et al. (2011) 4074:10.1145/1411509.1411511 3915:10.1023/A:1009802905533 3615:10.1007/3-540-44969-8_5 3565:Di Battista, Giuseppe; 3534:"The New Stoichiometry" 3345:10.1214/aoms/1177703572 3316:2027/mdp.39015095254010 3110:10.1145/1798596.1798608 3029:10.1287/mnsc.29.12.1384 2308:{\displaystyle K_{3,3}} 2082:unique games conjecture 2030:21 NP-complete problems 2020:edges. This problem is 1869:of the problem, and to 1828:weakly acyclic digraphs 1815:{\displaystyle K_{3,3}} 1403:{\displaystyle \Delta } 1325:{\displaystyle m/2+n/6} 1128:approximation algorithm 760:vertices, with natural 544:triconnected components 331:sizes from each other. 227:mathematical psychology 134:unique games conjecture 98:mathematical psychology 4687:Kenyon-Mathieu, Claire 4441:10.1006/jagm.1995.1022 4338:10.1006/jagm.1997.0864 2857: 2829: 2809: 2781: 2759: 2698: 2678: 2647: 2625: 2603: 2583: 2568:directed acyclic graph 2558: 2478: 2396: 2309: 2263: 2213: 2178: 2146: 2116: 2014: 1969: 1947: 1925: 1900: 1816: 1778: 1718: 1694: 1654: 1575: 1547: 1519: 1461: 1404: 1380: 1326: 1284: 1264: 1224: 1187: 1094: 1068: 1026: 994: 972: 910: 886: 864: 842: 776: 754: 717: 661: 610: 574: 539:biconnected components 530: 527:biconnected components 519: 487: 467: 445: 421: 399: 377: 348: 290:, breaking edges of a 214:and more generally in 189:directed acyclic graph 180: 66:directed acyclic graph 37: 5126:Guruswami, Venkatesan 5095:10.1145/509907.509915 5040:Annals of Mathematics 4837:(1979), "A1.1: GT8", 4773:10.1007/s101070100271 4654:Journal of Algorithms 4429:Journal of Algorithms 4326:Journal of Algorithms 3744:10.1145/322344.322351 2858: 2830: 2810: 2782: 2760: 2699: 2679: 2648: 2626: 2604: 2584: 2559: 2479: 2397: 2310: 2264: 2214: 2179: 2147: 2117: 2052:The complexity class 2015: 1970: 1948: 1926: 1893: 1843:reducible flow graphs 1817: 1779: 1719: 1695: 1655: 1576: 1548: 1520: 1462: 1405: 1381: 1327: 1285: 1265: 1225: 1188: 1095: 1069: 1027: 995: 973: 911: 887: 865: 843: 777: 755: 718: 662: 611: 609:{\displaystyle O(n!)} 575: 520: 500: 488: 468: 446: 422: 400: 378: 349: 300:layered graph drawing 220:dominance hierarchies 174: 78:optimization problems 35: 5609:NP-complete problems 5604:Graph theory objects 4990:Kann, Viggo (1992), 4650:Ramachandran, Vijaya 3581:, pp. 265–302, 3512:10.1364/ao.34.008125 2839: 2819: 2791: 2771: 2709: 2688: 2668: 2637: 2615: 2593: 2573: 2495: 2409: 2327: 2286: 2224: 2188: 2162: 2130: 2091: 2038:vertex cover problem 1979: 1959: 1937: 1915: 1793: 1732: 1708: 1668: 1611: 1557: 1531: 1473: 1416: 1394: 1338: 1294: 1274: 1254: 1205: 1147: 1084: 1040: 1016: 984: 927: 900: 876: 854: 790: 766: 744: 679: 632: 622:method based on the 588: 564: 509: 477: 457: 435: 411: 389: 367: 338: 292:process flow diagram 288:chemical engineering 284:process flowsheeting 275:synchronous circuits 86:chemical engineering 4701:, pp. 95–103, 4004:Bodlaender, Hans L. 3504:1995ApOpt..34.8125F 3104:(3): A55:1–A55:13, 2856:{\displaystyle m/3} 2808:{\displaystyle n/3} 2058:approximation ratio 2028:'s original set of 1863:randomized rounding 1574:{\displaystyle 8/9} 1141:approximation ratio 624:Held–Karp algorithm 620:dynamic programming 356:feedback vertex set 280:combinational logic 261:Kemeny–Young method 149:feedback vertex set 126:approximation ratio 5522:20.500.11850/73894 5343:10.1007/BF02017965 5089:, pp. 33–42, 4733:2009-01-15 at the 4621:10.1007/BF01582009 4483:10.1007/BF02579270 4234:Woeginger, Gerhard 4061:Journal of the ACM 3730:Journal of the ACM 3696:10.1007/PL00009191 3016:Management Science 2853: 2825: 2805: 2777: 2755: 2694: 2674: 2662:strongly connected 2643: 2621: 2599: 2579: 2554: 2520: 2474: 2434: 2392: 2352: 2305: 2259: 2209: 2201: 2174: 2142: 2112: 2104: 2010: 1965: 1943: 1921: 1901: 1812: 1774: 1714: 1690: 1650: 1603:strongly connected 1571: 1543: 1515: 1486: 1457: 1400: 1376: 1351: 1322: 1280: 1260: 1220: 1218: 1183: 1090: 1064: 1022: 990: 968: 906: 882: 860: 838: 772: 750: 713: 657: 606: 570: 531: 515: 483: 463: 441: 417: 395: 373: 344: 181: 38: 5571:978-3-642-45042-6 5159:10.1137/090756144 4882:10.1137/050623905 4835:Johnson, David S. 4831:Garey, Michael R. 4691:Johnson, David S. 4603:Grötschel, Martin 4518:, Second Series, 4124:978-3-030-00255-8 3624:978-3-540-42062-0 3588:978-0-13-301615-4 3571:Tamassia, Roberto 3498:(35): 8125–8136, 3444:978-3-642-17516-9 3217:978-0-429-04926-2 3023:(12): 1384–1392, 2881:"Main draw – Men" 2828:{\displaystyle m} 2780:{\displaystyle n} 2697:{\displaystyle n} 2677:{\displaystyle m} 2646:{\displaystyle D} 2624:{\displaystyle D} 2602:{\displaystyle D} 2582:{\displaystyle D} 2513: 2427: 2345: 2200: 2103: 2048:Inapproximability 1968:{\displaystyle k} 1946:{\displaystyle k} 1924:{\displaystyle k} 1830:, defined by the 1717:{\displaystyle N} 1585:Restricted inputs 1581:can be achieved. 1510: 1485: 1452: 1350: 1283:{\displaystyle n} 1263:{\displaystyle m} 1217: 1093:{\displaystyle t} 1025:{\displaystyle t} 993:{\displaystyle r} 909:{\displaystyle k} 885:{\displaystyle 4} 863:{\displaystyle n} 775:{\displaystyle k} 753:{\displaystyle n} 738:natural parameter 708: 582:graph would take 573:{\displaystyle n} 518:{\displaystyle d} 486:{\displaystyle G} 466:{\displaystyle G} 444:{\displaystyle G} 420:{\displaystyle G} 398:{\displaystyle G} 376:{\displaystyle G} 354:is the same as a 347:{\displaystyle G} 311:operating systems 244:, the problem in 193:topological order 153:undirected graphs 138:tournament graphs 130:inapproximability 54:feedback edge set 16:(Redirected from 5621: 5583: 5582: 5548: 5542: 5541: 5524: 5506: 5482: 5476: 5475: 5444: 5438: 5437: 5409:Roberts, Fred S. 5404: 5398: 5397: 5388: 5368: 5362: 5361: 5323: 5317: 5316: 5286:Bar-Noy, Amotz; 5283: 5277: 5276: 5267: 5242: 5236: 5235: 5210: 5195:Acta Informatica 5190: 5184: 5183: 5182: 5181: 5175: 5142: 5122: 5116: 5115: 5071: 5070: 5069: 5063: 5056: 5036: 5020: 5014: 5013: 5012: 5011: 5005: 4998: 4987: 4981: 4980: 4948: 4942: 4941: 4908: 4899: 4893: 4892: 4860: 4854: 4853: 4827: 4821: 4820: 4813:Karp, Richard M. 4809: 4803: 4802: 4801: 4800: 4743: 4737: 4725: 4683: 4677: 4676: 4646: 4640: 4639: 4599: 4593: 4592: 4552:Gabow, Harold N. 4548: 4539: 4538: 4511: 4502: 4501: 4461: 4452: 4451: 4425:Gabow, Harold N. 4421: 4412: 4407: 4392: 4383: 4382: 4355: 4349: 4348: 4314: 4308: 4307: 4306: 4305: 4262: 4256: 4255: 4254: 4253: 4230:Karpinski, Marek 4225: 4214: 4213: 4204: 4195:(1–3): 253–265, 4182: 4176: 4175: 4165:10.1109/12.24280 4142: 4136: 4135: 4108: 4091: 4085: 4084: 4055: 4049: 4048: 4031: 4000: 3991: 3990: 3966: 3960: 3959: 3940: 3934: 3933: 3898: 3889: 3888: 3855: 3849: 3848: 3831: 3822:(5): 1048–1084, 3809: 3800: 3799: 3783:(2–3): 249–269, 3770: 3764: 3763: 3746: 3737:(4): 1023–1048, 3724: 3715: 3714: 3665: 3654: 3653: 3634: 3628: 3627: 3603:Wagner, Dorothea 3598: 3592: 3591: 3562: 3556: 3555: 3554: 3553: 3529: 3523: 3522: 3487: 3481: 3480: 3465: 3456: 3455: 3428: 3409:Karpinski, Marek 3405: 3396: 3395: 3371: 3365: 3364: 3347: 3325: 3319: 3318: 3308: 3284:(291): 503–520, 3271: 3265: 3264: 3248:(3–4): 303–312, 3235: 3229: 3228: 3195: 3189: 3188: 3169: 3163: 3162: 3140:Animal Behaviour 3135: 3129: 3128: 3092:Coppersmith, Don 3088: 3082: 3081: 3056: 3047: 3041: 3039: 3010: 3004: 3003: 2971:(1–2): 143–149, 2958: 2947: 2946: 2918:Hubert, Lawrence 2914: 2903: 2902: 2901: 2900: 2877: 2862: 2860: 2859: 2854: 2849: 2834: 2832: 2831: 2826: 2814: 2812: 2811: 2806: 2801: 2786: 2784: 2783: 2778: 2766: 2764: 2762: 2761: 2756: 2754: 2753: 2741: 2724: 2723: 2703: 2701: 2700: 2695: 2683: 2681: 2680: 2675: 2652: 2650: 2649: 2644: 2632: 2630: 2628: 2627: 2622: 2608: 2606: 2605: 2600: 2588: 2586: 2585: 2580: 2565: 2563: 2561: 2560: 2555: 2553: 2552: 2548: 2526: 2521: 2519: 2518: 2505: 2485: 2483: 2481: 2480: 2475: 2470: 2469: 2465: 2440: 2435: 2433: 2432: 2419: 2403: 2401: 2399: 2398: 2393: 2388: 2387: 2383: 2358: 2353: 2351: 2350: 2337: 2320:Hamiltonian path 2314: 2312: 2311: 2306: 2304: 2303: 2270: 2268: 2266: 2265: 2260: 2255: 2254: 2253: 2252: 2218: 2216: 2215: 2210: 2202: 2193: 2183: 2181: 2180: 2175: 2153: 2151: 2149: 2148: 2143: 2123: 2121: 2119: 2118: 2113: 2105: 2096: 2019: 2017: 2016: 2011: 2003: 1986: 1974: 1972: 1971: 1966: 1954: 1952: 1950: 1949: 1944: 1930: 1928: 1927: 1922: 1909:decision version 1821: 1819: 1818: 1813: 1811: 1810: 1785: 1783: 1781: 1780: 1775: 1758: 1757: 1753: 1725: 1723: 1721: 1720: 1715: 1701: 1699: 1697: 1696: 1691: 1686: 1685: 1661: 1659: 1657: 1656: 1651: 1637: 1636: 1632: 1580: 1578: 1577: 1572: 1567: 1552: 1550: 1549: 1544: 1526: 1524: 1522: 1521: 1516: 1511: 1506: 1504: 1487: 1478: 1466: 1464: 1463: 1458: 1453: 1448: 1446: 1426: 1411: 1409: 1407: 1406: 1401: 1387: 1385: 1383: 1382: 1377: 1369: 1352: 1343: 1331: 1329: 1328: 1323: 1318: 1304: 1289: 1287: 1286: 1281: 1269: 1267: 1266: 1261: 1247:greedy algorithm 1231: 1229: 1227: 1226: 1221: 1219: 1210: 1194: 1192: 1190: 1189: 1184: 1122: 1109:polynomial delay 1099: 1097: 1096: 1091: 1075: 1073: 1071: 1070: 1065: 1033: 1031: 1029: 1028: 1023: 999: 997: 996: 991: 979: 977: 975: 974: 969: 955: 954: 945: 944: 917: 915: 913: 912: 907: 893: 891: 889: 888: 883: 869: 867: 866: 861: 849: 847: 845: 844: 839: 828: 827: 818: 817: 808: 807: 783: 781: 779: 778: 773: 759: 757: 756: 751: 727:polynomial space 724: 722: 720: 719: 714: 709: 704: 702: 697: 696: 668: 666: 664: 663: 658: 653: 652: 617: 615: 613: 612: 607: 581: 579: 577: 576: 571: 524: 522: 521: 516: 492: 490: 489: 484: 472: 470: 469: 464: 452: 450: 448: 447: 442: 428: 426: 424: 423: 418: 404: 402: 401: 396: 384: 382: 380: 379: 374: 353: 351: 350: 345: 273:information. In 270:sequential logic 201:round-robin play 185:tournament graph 175:The scores from 114:exponential time 62:acyclic subgraph 50:feedback arc set 46:graph algorithms 21: 5629: 5628: 5624: 5623: 5622: 5620: 5619: 5618: 5599:Directed graphs 5589: 5588: 5587: 5586: 5572: 5549: 5545: 5483: 5479: 5445: 5441: 5405: 5401: 5369: 5365: 5324: 5320: 5306:10.1137/0403002 5284: 5280: 5243: 5239: 5191: 5187: 5179: 5177: 5173: 5140: 5134:Charikar, Moses 5123: 5119: 5105: 5067: 5065: 5061: 5034: 5021: 5017: 5009: 5007: 5003: 4996: 4988: 4984: 4949: 4945: 4906: 4900: 4896: 4861: 4857: 4851: 4828: 4824: 4810: 4806: 4798: 4796: 4744: 4740: 4735:Wayback Machine 4684: 4680: 4647: 4643: 4600: 4596: 4574: 4549: 4542: 4512: 4505: 4462: 4455: 4422: 4415: 4393: 4386: 4356: 4352: 4315: 4311: 4303: 4301: 4263: 4259: 4251: 4249: 4226: 4217: 4183: 4179: 4143: 4139: 4125: 4092: 4088: 4056: 4052: 4001: 3994: 3967: 3963: 3941: 3937: 3899: 3892: 3878: 3856: 3852: 3810: 3803: 3771: 3767: 3725: 3718: 3666: 3657: 3635: 3631: 3625: 3599: 3595: 3589: 3563: 3559: 3551: 3549: 3530: 3526: 3488: 3484: 3466: 3459: 3445: 3413:Cheong, Otfried 3406: 3399: 3375:Kemeny, John G. 3372: 3368: 3326: 3322: 3314: 3290:10.2307/2281911 3272: 3268: 3236: 3232: 3218: 3200:Insect Behavior 3196: 3192: 3170: 3166: 3136: 3132: 3089: 3085: 3054: 3048: 3044: 3011: 3007: 2959: 2950: 2915: 2906: 2898: 2896: 2879: 2878: 2874: 2869: 2845: 2840: 2837: 2836: 2820: 2817: 2816: 2797: 2792: 2789: 2788: 2772: 2769: 2768: 2749: 2745: 2737: 2719: 2715: 2710: 2707: 2706: 2705: 2689: 2686: 2685: 2669: 2666: 2665: 2660:whenever it is 2638: 2635: 2634: 2616: 2613: 2612: 2610: 2594: 2591: 2590: 2574: 2571: 2570: 2544: 2540: 2536: 2522: 2514: 2501: 2500: 2498: 2496: 2493: 2492: 2491: 2461: 2457: 2453: 2436: 2428: 2415: 2414: 2412: 2410: 2407: 2406: 2405: 2379: 2375: 2371: 2354: 2346: 2333: 2332: 2330: 2328: 2325: 2324: 2323: 2293: 2289: 2287: 2284: 2283: 2280:min-max theorem 2276: 2242: 2238: 2237: 2233: 2225: 2222: 2221: 2220: 2191: 2189: 2186: 2185: 2163: 2160: 2159: 2131: 2128: 2127: 2125: 2094: 2092: 2089: 2088: 2086: 2050: 2026:Richard M. Karp 1999: 1982: 1980: 1977: 1976: 1960: 1957: 1956: 1938: 1935: 1934: 1932: 1916: 1913: 1912: 1905:NP-completeness 1888: 1883: 1875:expander graphs 1800: 1796: 1794: 1791: 1790: 1749: 1745: 1741: 1733: 1730: 1729: 1727: 1709: 1706: 1705: 1703: 1681: 1677: 1669: 1666: 1665: 1663: 1628: 1624: 1620: 1612: 1609: 1608: 1606: 1587: 1563: 1558: 1555: 1554: 1532: 1529: 1528: 1505: 1500: 1476: 1474: 1471: 1470: 1468: 1447: 1442: 1422: 1417: 1414: 1413: 1395: 1392: 1391: 1389: 1365: 1341: 1339: 1336: 1335: 1333: 1314: 1300: 1295: 1292: 1291: 1275: 1272: 1271: 1255: 1252: 1251: 1208: 1206: 1203: 1202: 1200: 1148: 1145: 1144: 1143: 1137: 1136: 1131: 1124: 1117: 1085: 1082: 1081: 1041: 1038: 1037: 1035: 1017: 1014: 1013: 1009: 985: 982: 981: 950: 946: 940: 936: 928: 925: 924: 922: 901: 898: 897: 895: 877: 874: 873: 871: 855: 852: 851: 823: 819: 813: 809: 803: 799: 791: 788: 787: 785: 767: 764: 763: 761: 745: 742: 741: 703: 698: 692: 688: 680: 677: 676: 674: 648: 644: 633: 630: 629: 627: 589: 586: 585: 583: 565: 562: 561: 560: 552: 510: 507: 506: 478: 475: 474: 458: 455: 454: 436: 433: 432: 430: 412: 409: 408: 406: 390: 387: 386: 368: 365: 364: 362: 339: 336: 335: 324: 319: 235:log-likelihoods 169: 122:polynomial time 30: 23: 22: 15: 12: 11: 5: 5627: 5617: 5616: 5611: 5606: 5601: 5585: 5584: 5570: 5543: 5497:(6): 859–873, 5487:Sudakov, Benny 5477: 5459:(3): 107–111, 5439: 5421:(1–3): 39–76, 5399: 5379:(3): 328–332, 5363: 5337:(2): 131–144, 5318: 5278: 5246:Lovász, László 5237: 5185: 5153:(3): 878–914, 5117: 5103: 5047:(1): 439–485, 5015: 4982: 4964:(1): 136–153, 4943: 4894: 4876:(1): 137–142, 4855: 4849: 4822: 4804: 4747:Arora, Sanjeev 4738: 4678: 4660:(3): 299–313, 4641: 4594: 4572: 4540: 4522:(3): 369–374, 4503: 4477:(2): 145–153, 4453: 4435:(3): 586–628, 4413: 4408:, as cited by 4384: 4366:(3): 133–140, 4350: 4322:Shor, Peter W. 4318:Berger, Bonnie 4309: 4280:(6): 319–323, 4257: 4215: 4177: 4159:(5): 756–761, 4137: 4123: 4086: 4050: 4014:(3): 420–432, 3992: 3982:(2): 296–297, 3961: 3951:(2): 238–245, 3935: 3909:(2): 235–251, 3890: 3876: 3850: 3801: 3765: 3716: 3690:(2): 151–174, 3655: 3629: 3623: 3593: 3587: 3557: 3544:(3): 120–125, 3524: 3492:Applied Optics 3482: 3457: 3443: 3397: 3387:(4): 577–591, 3366: 3338:(2): 739–747, 3320: 3266: 3230: 3216: 3190: 3180:(3): 199–213, 3164: 3146:(4): 917–938, 3130: 3083: 3065:(5): 776–787, 3042: 3005: 2948: 2904: 2871: 2870: 2868: 2865: 2852: 2848: 2844: 2824: 2804: 2800: 2796: 2776: 2752: 2748: 2744: 2740: 2736: 2733: 2730: 2727: 2722: 2718: 2714: 2693: 2673: 2642: 2620: 2598: 2578: 2551: 2547: 2543: 2539: 2535: 2532: 2529: 2525: 2517: 2512: 2509: 2504: 2473: 2468: 2464: 2460: 2456: 2452: 2449: 2446: 2443: 2439: 2431: 2426: 2423: 2418: 2391: 2386: 2382: 2378: 2374: 2370: 2367: 2364: 2361: 2357: 2349: 2344: 2341: 2336: 2302: 2299: 2296: 2292: 2275: 2272: 2258: 2251: 2248: 2245: 2241: 2236: 2232: 2229: 2208: 2205: 2199: 2196: 2173: 2170: 2167: 2141: 2138: 2135: 2111: 2108: 2102: 2099: 2049: 2046: 2009: 2006: 2002: 1998: 1995: 1992: 1989: 1985: 1964: 1942: 1920: 1887: 1884: 1882: 1879: 1809: 1806: 1803: 1799: 1773: 1770: 1767: 1764: 1761: 1756: 1752: 1748: 1744: 1740: 1737: 1713: 1689: 1684: 1680: 1676: 1673: 1649: 1646: 1643: 1640: 1635: 1631: 1627: 1623: 1619: 1616: 1586: 1583: 1570: 1566: 1562: 1542: 1539: 1536: 1514: 1509: 1503: 1499: 1496: 1493: 1490: 1484: 1481: 1456: 1451: 1445: 1441: 1438: 1435: 1432: 1429: 1425: 1421: 1399: 1375: 1372: 1368: 1364: 1361: 1358: 1355: 1349: 1346: 1321: 1317: 1313: 1310: 1307: 1303: 1299: 1279: 1259: 1243: 1242: 1239: 1236: 1216: 1213: 1182: 1179: 1176: 1173: 1170: 1167: 1164: 1161: 1158: 1155: 1152: 1132: 1125: 1119: 1116: 1113: 1089: 1063: 1060: 1057: 1054: 1051: 1048: 1045: 1021: 989: 967: 964: 961: 958: 953: 949: 943: 939: 935: 932: 905: 881: 859: 837: 834: 831: 826: 822: 816: 812: 806: 802: 798: 795: 771: 749: 712: 707: 701: 695: 691: 687: 684: 656: 651: 647: 643: 640: 637: 605: 602: 599: 596: 593: 569: 551: 548: 514: 482: 462: 440: 416: 394: 372: 358:of a directed 343: 328:complement set 323: 320: 318: 315: 309:resolution in 266: 265: 253: 238: 223: 208: 168: 165: 157:spanning trees 58:directed graph 28: 9: 6: 4: 3: 2: 5626: 5615: 5612: 5610: 5607: 5605: 5602: 5600: 5597: 5596: 5594: 5581: 5577: 5573: 5567: 5563: 5559: 5555: 5547: 5540: 5536: 5532: 5528: 5523: 5518: 5514: 5510: 5505: 5500: 5496: 5492: 5488: 5481: 5474: 5470: 5466: 5462: 5458: 5454: 5450: 5443: 5436: 5432: 5428: 5424: 5420: 5416: 5415: 5410: 5403: 5396: 5392: 5387: 5382: 5378: 5374: 5367: 5360: 5356: 5352: 5348: 5344: 5340: 5336: 5332: 5328: 5322: 5315: 5311: 5307: 5303: 5299: 5295: 5294: 5289: 5282: 5275: 5271: 5266: 5261: 5258:(2): 96–103, 5257: 5253: 5252: 5247: 5241: 5234: 5230: 5226: 5222: 5218: 5214: 5209: 5204: 5200: 5196: 5189: 5172: 5168: 5164: 5160: 5156: 5152: 5148: 5147: 5139: 5135: 5131: 5130:Håstad, Johan 5127: 5121: 5114: 5110: 5106: 5104:1-58113-495-9 5100: 5096: 5092: 5088: 5084: 5083:Reif, John H. 5080: 5079:Safra, Samuel 5076: 5060: 5055: 5050: 5046: 5042: 5041: 5033: 5029: 5028:Safra, Samuel 5025: 5019: 5002: 4995: 4994: 4986: 4979: 4975: 4971: 4967: 4963: 4959: 4958: 4953: 4947: 4940: 4936: 4932: 4928: 4924: 4920: 4916: 4912: 4905: 4898: 4891: 4887: 4883: 4879: 4875: 4871: 4870: 4865: 4859: 4852: 4850:0-7167-1045-5 4846: 4842: 4841: 4836: 4832: 4826: 4818: 4814: 4808: 4794: 4790: 4786: 4782: 4778: 4774: 4770: 4766: 4762: 4761: 4756: 4752: 4748: 4742: 4736: 4732: 4729: 4724: 4720: 4716: 4712: 4708: 4704: 4700: 4696: 4692: 4688: 4682: 4675: 4671: 4667: 4663: 4659: 4655: 4651: 4645: 4638: 4634: 4630: 4626: 4622: 4618: 4614: 4610: 4609: 4604: 4598: 4591: 4587: 4583: 4579: 4575: 4573:0-8186-4370-6 4569: 4565: 4561: 4557: 4553: 4547: 4545: 4537: 4533: 4529: 4525: 4521: 4517: 4510: 4508: 4500: 4496: 4492: 4488: 4484: 4480: 4476: 4472: 4471: 4470:Combinatorica 4466: 4465:Frank, András 4460: 4458: 4450: 4446: 4442: 4438: 4434: 4430: 4426: 4420: 4418: 4411: 4406: 4402: 4398: 4391: 4389: 4381: 4377: 4373: 4369: 4365: 4361: 4354: 4347: 4343: 4339: 4335: 4331: 4327: 4323: 4319: 4313: 4299: 4295: 4291: 4287: 4283: 4279: 4275: 4271: 4267: 4261: 4247: 4243: 4239: 4235: 4231: 4224: 4222: 4220: 4212: 4208: 4203: 4198: 4194: 4190: 4189: 4181: 4174: 4170: 4166: 4162: 4158: 4154: 4153: 4148: 4147:Sahni, Sartaj 4145:Lin, Lishin; 4141: 4134: 4130: 4126: 4120: 4116: 4112: 4107: 4102: 4098: 4090: 4083: 4079: 4075: 4071: 4067: 4063: 4062: 4054: 4047: 4043: 4039: 4035: 4030: 4025: 4021: 4017: 4013: 4009: 4005: 3999: 3997: 3989: 3985: 3981: 3977: 3976: 3971: 3965: 3958: 3954: 3950: 3946: 3939: 3932: 3928: 3924: 3920: 3916: 3912: 3908: 3904: 3897: 3895: 3887: 3883: 3879: 3877:0-7803-0593-0 3873: 3869: 3865: 3861: 3854: 3847: 3843: 3839: 3835: 3830: 3825: 3821: 3817: 3816: 3808: 3806: 3798: 3794: 3790: 3786: 3782: 3778: 3777: 3769: 3762: 3758: 3754: 3750: 3745: 3740: 3736: 3732: 3731: 3723: 3721: 3713: 3709: 3705: 3701: 3697: 3693: 3689: 3685: 3684: 3679: 3675: 3671: 3664: 3662: 3660: 3652: 3648: 3644: 3640: 3633: 3626: 3620: 3616: 3612: 3608: 3604: 3597: 3590: 3584: 3580: 3579:Prentice Hall 3576: 3572: 3568: 3561: 3547: 3543: 3539: 3535: 3528: 3521: 3517: 3513: 3509: 3505: 3501: 3497: 3493: 3486: 3479: 3475: 3471: 3464: 3462: 3454: 3450: 3446: 3440: 3436: 3432: 3427: 3422: 3418: 3414: 3410: 3404: 3402: 3394: 3390: 3386: 3382: 3381: 3376: 3370: 3363: 3359: 3355: 3351: 3346: 3341: 3337: 3333: 3332: 3324: 3317: 3312: 3307: 3303: 3299: 3295: 3291: 3287: 3283: 3279: 3278: 3270: 3263: 3259: 3255: 3251: 3247: 3243: 3242: 3234: 3227: 3223: 3219: 3213: 3209: 3205: 3201: 3194: 3187: 3183: 3179: 3175: 3168: 3161: 3157: 3153: 3149: 3145: 3141: 3134: 3127: 3123: 3119: 3115: 3111: 3107: 3103: 3099: 3098: 3093: 3087: 3080: 3076: 3072: 3068: 3064: 3060: 3053: 3046: 3038: 3034: 3030: 3026: 3022: 3018: 3017: 3009: 3002: 2998: 2994: 2990: 2986: 2982: 2978: 2974: 2970: 2966: 2965: 2957: 2955: 2953: 2945: 2941: 2937: 2933: 2929: 2925: 2924: 2919: 2913: 2911: 2909: 2894: 2890: 2886: 2882: 2876: 2872: 2864: 2850: 2846: 2842: 2822: 2802: 2798: 2794: 2774: 2750: 2746: 2742: 2738: 2731: 2728: 2725: 2720: 2716: 2691: 2671: 2663: 2659: 2654: 2640: 2618: 2596: 2576: 2569: 2549: 2545: 2541: 2537: 2533: 2530: 2527: 2523: 2510: 2507: 2489: 2466: 2462: 2458: 2454: 2447: 2444: 2441: 2437: 2424: 2421: 2384: 2380: 2376: 2372: 2362: 2359: 2355: 2342: 2339: 2321: 2316: 2300: 2297: 2294: 2290: 2281: 2271: 2249: 2246: 2243: 2239: 2234: 2227: 2206: 2203: 2197: 2194: 2171: 2168: 2165: 2157: 2139: 2136: 2133: 2109: 2106: 2100: 2097: 2083: 2079: 2074: 2071: 2067: 2063: 2059: 2055: 2045: 2041: 2039: 2035: 2034:Eugene Lawler 2031: 2027: 2023: 2007: 2004: 1993: 1987: 1962: 1940: 1918: 1910: 1906: 1897: 1892: 1878: 1876: 1872: 1868: 1864: 1860: 1856: 1852: 1847: 1844: 1839: 1837: 1834:of a certain 1833: 1829: 1825: 1807: 1804: 1801: 1797: 1789: 1788:utility graph 1768: 1765: 1762: 1759: 1754: 1750: 1746: 1742: 1735: 1711: 1682: 1678: 1671: 1644: 1641: 1638: 1633: 1629: 1625: 1621: 1614: 1604: 1600: 1596: 1592: 1591:planar graphs 1582: 1568: 1564: 1560: 1540: 1537: 1501: 1497: 1488: 1482: 1479: 1443: 1439: 1430: 1427: 1423: 1419: 1370: 1366: 1362: 1353: 1347: 1344: 1319: 1315: 1311: 1308: 1305: 1301: 1297: 1277: 1257: 1248: 1240: 1237: 1234: 1233: 1232: 1214: 1211: 1197: 1177: 1174: 1171: 1168: 1165: 1162: 1159: 1156: 1150: 1142: 1135: 1129: 1112: 1110: 1106: 1101: 1100:is possible. 1087: 1079: 1058: 1055: 1052: 1049: 1043: 1019: 1012: 1007: 1006:spanning tree 1003: 987: 962: 959: 956: 951: 947: 941: 937: 930: 919: 903: 879: 857: 832: 829: 824: 820: 814: 810: 804: 800: 793: 769: 747: 739: 735: 730: 728: 705: 699: 693: 689: 682: 672: 649: 645: 641: 635: 625: 621: 600: 597: 591: 567: 558: 547: 545: 540: 536: 528: 512: 504: 499: 495: 480: 460: 438: 414: 392: 370: 361: 357: 341: 332: 329: 314: 312: 308: 303: 301: 296: 293: 289: 285: 281: 276: 271: 262: 258: 257:ranked voting 254: 251: 247: 243: 239: 236: 232: 228: 224: 221: 217: 213: 209: 206: 202: 198: 197: 196: 194: 191:whose unique 190: 186: 178: 173: 164: 162: 158: 154: 150: 145: 143: 142:planar graphs 139: 135: 131: 127: 123: 119: 115: 111: 107: 106:graph drawing 103: 99: 95: 94:ranked voting 91: 87: 82: 79: 75: 71: 67: 63: 59: 55: 51: 47: 43: 34: 27: 19: 5553: 5546: 5494: 5490: 5480: 5456: 5452: 5442: 5418: 5412: 5402: 5376: 5375:, Series B, 5372: 5366: 5334: 5330: 5321: 5297: 5291: 5288:Naor, Joseph 5281: 5255: 5254:, Series B, 5249: 5240: 5198: 5194: 5188: 5178:, retrieved 5150: 5144: 5120: 5086: 5066:, retrieved 5044: 5038: 5018: 5008:, retrieved 4992: 4985: 4961: 4955: 4952:Ausiello, G. 4946: 4914: 4910: 4897: 4873: 4867: 4858: 4839: 4825: 4816: 4807: 4797:, retrieved 4764: 4758: 4751:Frieze, Alan 4741: 4698: 4695:Feige, Uriel 4681: 4657: 4653: 4644: 4615:(1): 28–42, 4612: 4606: 4597: 4555: 4519: 4515: 4474: 4468: 4432: 4428: 4405:1721.1/86548 4396: 4363: 4359: 4353: 4329: 4325: 4312: 4302:, retrieved 4277: 4273: 4266:Eades, Peter 4260: 4250:, retrieved 4241: 4192: 4186: 4180: 4156: 4150: 4140: 4096: 4089: 4065: 4059: 4053: 4011: 4007: 3979: 3973: 3964: 3948: 3944: 3938: 3906: 3902: 3859: 3853: 3819: 3813: 3780: 3774: 3768: 3734: 3728: 3687: 3683:Algorithmica 3681: 3674:Schieber, B. 3642: 3638: 3632: 3606: 3596: 3574: 3567:Eades, Peter 3560: 3550:, retrieved 3541: 3537: 3527: 3495: 3491: 3485: 3469: 3416: 3384: 3378: 3369: 3335: 3329: 3323: 3281: 3275: 3269: 3245: 3239: 3233: 3199: 3193: 3177: 3173: 3167: 3143: 3139: 3133: 3101: 3095: 3086: 3062: 3058: 3045: 3020: 3014: 3008: 2968: 2962: 2930:(1): 32–52, 2927: 2921: 2897:, retrieved 2884: 2875: 2655: 2317: 2277: 2075: 2051: 2042: 1902: 1859:dense graphs 1848: 1840: 1827: 1589:In directed 1588: 1244: 1198: 1138: 1102: 1002:circuit rank 920: 894:independent 737: 731: 557:permutations 553: 532: 333: 325: 322:Equivalences 304: 297: 267: 182: 167:Applications 161:circuit rank 146: 92:resolution, 83: 73: 69: 61: 53: 49: 42:graph theory 39: 26: 5327:Spencer, J. 5300:(1): 7–20, 5201:(1): 1–15, 5075:Dinur, Irit 5024:Dinur, Irit 4767:(1): 1–36, 4726:; see also 4332:(1): 1–18, 4068:(5): 1–19, 3645:: 171–182, 3478:1721.1/4763 2022:NP-complete 1886:NP-hardness 1871:derandomize 1853:, it has a 1851:tournaments 1832:integrality 1824:graph minor 1115:Approximate 1105:linear time 212:primatology 5593:Categories 5180:2021-07-31 5068:2021-07-29 5010:2007-10-11 4917:(1): 1–4, 4864:Alon, Noga 4799:2021-08-03 4304:2021-08-01 4252:2021-07-29 4106:1707.01470 3970:Lawler, E. 3829:1702.07612 3668:Even, G.; 3552:2021-08-02 3241:Biometrika 2964:Biometrika 2899:2021-11-14 2867:References 2684:edges and 2658:Euler tour 2488:almost all 1270:edges and 1076:Under the 762:parameter 360:line graph 317:Algorithms 246:statistics 5504:1202.2602 5359:119894999 5208:1402.2843 4637:206798683 4029:1956/4556 3931:207632524 3886:122603659 3678:Sudan, M. 3426:1006.4396 3226:203898549 2531:− 2445:− 2366:Ω 2363:− 2250:ε 2247:− 2207:ε 2204:− 2166:ε 2134:ε 2110:ε 2070:reduction 2005:− 1763:⁡ 1642:⁡ 1535:Δ 1508:Δ 1492:Ω 1450:Δ 1434:Ω 1398:Δ 1357:Ω 1175:⁡ 1169:⁡ 1160:⁡ 1111:per set. 1056:⁡ 1011:treewidth 960:⁡ 872:constant 525:into two 242:seriation 120:time. 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Index

Minimum feedback arc set

graph theory
graph algorithms
directed graph
directed acyclic graph
optimization problems
chemical engineering
deadlock
ranked voting
mathematical psychology
ethology
graph drawing
NP-hard
exponential time
fixed-parameter tractable
polynomial time
approximation ratio
inapproximability
unique games conjecture
tournament graphs
planar graphs
feedback vertex set
undirected graphs
spanning trees
circuit rank

men's beach volleyball at the 2016 Olympics
tournament graph
directed acyclic graph

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