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| Content Provider | IEEE Xplore Digital Library |
|---|---|
| Author | Henglein, F. Rehof, J. |
| Copyright Year | 1997 |
| Description | Author affiliation: Dept. of Comput. Sci., Copenhagen Univ., Denmark (Henglein, F.) |
| Abstract | A subtyping /spl tau//spl les//spl tau/' is entailed by a set of subtyping constraints C, written C |=/spl tau//spl les//spl tau/', if every valuation (mapping of type variables to ground types) that satisfies C also satisfies /spl tau//spl les//spl tau/'. We study the complexity of subtype entailment for simple types over lattices of base types. We show that: deciding C |=/spl tau//spl les//spl tau/' is coNP-complete; deciding C |=/spl alpha//spl les//spl beta/ for consistent, atomic C and /spl alpha/, /spl beta/ atomic can be done in linear time. The structural lower (coNP-hardness) and upper (membership in coNP) bounds as well as the optimal algorithm for atomic entailment are new. The coNP-hardness result indicates that entailment is strictly harder than satisfiability, which is known to be in PTIME for lattices of base types. The proof of coNP-completeness gives an improved algorithm for deciding entailment and puts a precise complexity-theoretic marker on the intuitive "exponential explosion" in the algorithm. Central to our results is a novel characterization of C |=/spl alpha//spl les//spl beta/ for atomic, consistent C. This is the basis for correctness of the linear-time algorithm as well as a complete axiomatization of C |=/spl alpha//spl les//spl beta/ for atomic C by extending the usual proof rules for subtype inference. It also incorporates the fundamental insight for understanding the structural complexity bounds in the general case. |
| Starting Page | 352 |
| Ending Page | 361 |
| File Size | 949222 |
| Page Count | 10 |
| File Format | |
| ISBN | 0818679255 |
| ISSN | 10436871 |
| DOI | 10.1109/LICS.1997.614961 |
| Language | English |
| Publisher | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Publisher Date | 1997-06-29 |
| Access Restriction | Subscribed |
| Rights Holder | Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
| Subject Keyword | Inference algorithms Calculus Lattices Power generation Computer science Cost accounting Explosions Computer languages Logic Power system modeling |
| Content Type | Text |
| Resource Type | Article |
| Subject | Mathematics Software |
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