Discrete Mathematics - First Japan Conference on Graph Theory and Applications
On the computational complexity of upper fractional domination
Discrete Applied Mathematics
Completeness in approximation classes
Information and Computation
Approximating the minimum maximal independence number
Information Processing Letters
Approximate solution of NP optimization problems
Theoretical Computer Science
On the hardness of approximating minimization problems
Journal of the ACM (JACM)
Approximation algorithms for the achromatic number
SODA '97 Proceedings of the eighth annual ACM-SIAM symposium on Discrete algorithms
Constant Ratio Approximations of the Weighted Feedback Vertex Set Problem for Undirected Graphs
ISAAC '95 Proceedings of the 6th International Symposium on Algorithms and Computation
Structure in Approximation Classes (Extended Abstract)
COCOON '95 Proceedings of the First Annual International Conference on Computing and Combinatorics
Hardness of Approximating Problems on Cubic Graphs
CIAC '97 Proceedings of the Third Italian Conference on Algorithms and Complexity
Clique is hard to approximate within n1-
FOCS '96 Proceedings of the 37th Annual Symposium on Foundations of Computer Science
On syntactic versus computational views of approximability
SFCS '94 Proceedings of the 35th Annual Symposium on Foundations of Computer Science
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We study hardness of approximating several minimaximal and maximinimal NP-optimization problems related to the minimum linear ordering problem (MINLOP). MINLOP is to find a minimum weight acyclic tournament in a given arc-weighted complete digraph. MINLOP is APX-hard but its unweighted version is polynomial time solvable. We prove that, MIN-MAX-SUBDAG problem, which is a generalization of MINLOP, and requires to find a minimum cardinality maximal acyclic subdigraph of a given digraph, is, however APX-hard. Using results of Hastad concerning hardness of approximating independence number of a graph we then prove similar results concerning MAX-MIN-VC (respectively, MAX-MIN-FVS) which requires to find a maximum cardinality minimal vertex cover in a given graph (respectively, a maximum cardinality minimal feedback vertex set in a given digraph). We also prove APX-hardness of these and several related problems on various degree bounded graphs and digraphs.