Enumerating Answers to First-Order Queries over Databases of Low Degree
Résumé
A class of relational databases has low degree if for all δ > 0, all but finitely many databases in the class have degree at most n δ , where n is the size of the database. Typical examples are databases of bounded degree or of degree bounded by log n. It is known that over a class of databases having low degree, first-order boolean queries can be checked in pseudo-linear time, i.e. for all ε > 0 in time bounded by n 1+ε. We generalize this result by considering query evaluation. We show that counting the number of answers to a query can be done in pseudo-linear time and that after a pseudo-linear time preprocessing we can test in constant time whether a given tuple is a solution to a query or enumerate the answers to a query with constant delay.
Domaines
Informatique et langage [cs.CL]Origine | Fichiers produits par l'(les) auteur(s) |
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