Scheduling jobs with fixed start and end times
Discrete Applied Mathematics
Analytic models and ambiguity of context-free languages
Theoretical Computer Science
Graph classes: a survey
On universally easy classes for NP-complete problems
SODA '01 Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms
The growth function of context-free languages
Theoretical Computer Science
Disjoint paths in circular arc graphs
Nordic Journal of Computing
On the density of regular and context-free languages
COCOON'10 Proceedings of the 16th annual international conference on Computing and combinatorics
Characterizations and Existence of Easy Sets without Hard Subsets
Fundamenta Informaticae - Theory that Counts: To Oscar Ibarra on His 70th Birthday
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We explore the natural question of whether all NP-complete problems have a common restriction under which they are polynomially solvable. More precisely, we study what languages are universally easy in that their intersection with any NP-complete problem is in P (universally polynomial) or at least no longer NP-complete (universally simplifying). In particular, we give a polynomial-time algorithm to determine whether a regular language is universally easy. While our approach is language-theoretic, the results bear directly on finding polynomial-time solutions to very broad and useful classes of problems.