Chain Queries Expressible by Linear Datalog Programs
ثبت نشده
چکیده
منابع مشابه
Linearisability on datalog programs
LinearDatalog programs are programs whose clauses have at most one intensional atom in their bodies We explore syntactic classes of Datalog programs syntactically non linear which turn out to express no more than the queries expressed by linear Datalog programs In particular we investigate linearisability of database queries corresponding to piecewise linear Datalog programs and chain queries a...
متن کاملThe Expressiveness of Datalog Circuits (DAC)
We deene a new logic query language, called DAC, which is an extension of Datalog. We exhibit queries which are not Datalog expressible but are DAC expressible. We also prove non-expressiveness results for DAC and we infer various strict hierarchies obtained by allowing more rapidly growing functions on the bound parameters. A Datalog program is an existential inductive deenition on a class of ...
متن کاملThe expressiveness of DAC
We de.ne a new logic-based query language, called DAC, which is an extension of Datalog. A DAC(w(n); h(n))(b(n))-program consists of a family of Datalog programs Pn such that w(n); h(n); b(n) bound the width of rules, the number of rules, and the recursion depth of any Pn, respectively. We exhibit queries which are not Datalog expressible but are DAC expressible. We also prove non-expressivenes...
متن کاملGraph-Based Processing of Logic Programs
A lot of practical recursive logic queries to a deductive database are expressed by linear recursive Datalog programs with exactly one recursive rule, so-called linear sirups. We give a characterization of k-sided linear Datalog sirups { the concept was introduced by Naughton in 22] { based on a graph model and present a normal form to which every linear Datalog sirup can be transformed. Normal...
متن کاملCombined Tractability of Query Evaluation via Tree Automata and Cycluits (Extended Version)
We investigate parameterizations of both database instances and queries that make query evaluation fixed-parameter tractable in combined complexity. We introduce a new Datalog fragment with stratified negation, intensional-clique-guarded Datalog (ICG-Datalog), with linear-time evaluation on structures of bounded treewidth for programs of bounded rule size. Such programs capture in particular co...
متن کامل