Intersection Optimization is NP-Complete
نویسندگان
چکیده
Finite state methods for natural language processing often require the construction and the intersection of several automata. In this paper we investigate the question of determining the best order in which these intersections should be performed. We take as an example lexical disambiguation in polarity grammars. We show that there is no efficient way to minimize the state complexity of these intersections.
منابع مشابه
Advancements on SEFE and Partitioned Book Embedding problems
In this work we investigate the complexity of some problems related to the Simultaneous Embedding with Fixed Edges (SEFE) of k planar graphs and the PARTITIONED k-PAGE BOOK EMBEDDING (PBE-k) problems, which are known to be equivalent under certain conditions. While the computational complexity of SEFE for k = 2 is still a central open question in Graph Drawing, the problem is NP-complete for k ...
متن کاملApproximation hardness of optimization problems in intersection graphs of d-dimensional boxes
The Maximum Independent Set problem in d-box graphs, i.e., in the intersection graphs of axis-parallel rectangles in Rd, is a challenge open problem. For any fixed d ≥ 2 the problem is NP-hard and no approximation algorithm with ratio o(logd−1 n) is known. In some restricted cases, e.g., for d-boxes with bounded aspect ratio, a PTAS exists [17]. In this paper we prove APX-hardness (and hence no...
متن کاملConvex Polygon Intersection Graphs
Geometric intersection graphs are graphs determined by the intersections of certain geometric objects. We study the complexity of visualizing an arrangement of objects that induces a given intersection graph. We give a general framework for describing classes of geometric intersection graphs, using arbitrary finite base sets of rationally given convex polygons and rationally-constrained affine ...
متن کاملIntersection Type Matching with Subtyping
Type matching problems occur in a number of contexts, including library search, component composition, and inhabitation. We consider the intersection type matching problem under the standard notion of subtyping for intersection types: Given intersection types τ and σ, where σ is a constant type, does there exist a type substitution S such that S(τ) is a subtype of σ? We show that the matching p...
متن کاملOn Finding Additive, Superadditive and Subadditive Set-functions Subject to Linear Inequalities
Complexity results are obtained with regard to problems of finding solutions to set of linear inequalities which are compatible with some set-functions and a prescribed intersection graph. It is shown that the additive case is SP-complete, the superadditive case is coSP-complete, and the subadditive case is in P. 0 1 1 Finding Addit,ive, Superaddit.ive and Subadditive Set-Functions Subject to L...
متن کامل