Source-tracking unification
We propose a path-based framework for deriving and simplifying source-tracking information for first-order term unification in the empty theory. Such a framework is useful for diagnosing unification-based systems, including debugging of type errors in programs and the generation of success and failu...
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| Vydané v: | Information and computation Ročník 201; číslo 2; s. 121 - 159 |
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| Hlavní autori: | , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
San Diego, CA
Elsevier Inc
01.01.2003
Elsevier |
| Predmet: | |
| ISSN: | 0890-5401, 1090-2651 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | We propose a path-based framework for deriving and simplifying source-tracking information for first-order term unification in the empty theory. Such a framework is useful for diagnosing unification-based systems, including debugging of type errors in programs and the generation of success and failure proofs in logic programming. The objects of source-tracking are deductions in the logic of term unification. The semantics of deductions are paths over a unification graph whose labels form the suffix language of a semi-Dyck set. Based on this idea of unification paths, two algorithms for generating proofs are presented: the first uses context-free labeled shortest-path algorithms to generate optimal (shortest) proofs in time
O
(
n
3) for a fixed signature, where
n is the number of vertices of the unification graph. The second algorithm integrates easily with standard unification algorithms, entailing an overhead of only a constant factor, but generates non-optimal proofs. These non-optimal proofs may be further simplified by group rewrite rules. |
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| ISSN: | 0890-5401 1090-2651 |
| DOI: | 10.1016/j.ic.2004.10.013 |