Fixpoint Path Queries
نویسندگان
چکیده
The paper proposes two fixpoint path query languages Path-Fixpoint and Path-While for unstructured data whose expressive power is that of Fixpoint and While queries respectively. These languages are multi-sorted like logic languages integrating fixpoint path expressions.
منابع مشابه
Lower Bound for Evaluation of mu-nu Fixpoint
We consider a fixpoint expressions μy.νx. f (x,y) over the lattice {0,1}n, where f : {0,1}2n → {0,1}n is any monotone function. We study only algorithms for calculating these expressions using f only as a black-box: they may only ask for the value of f for given arguments. We show that any such algorithm has to do at least about n2 queries to the function f , namely Ω ( n2 logn ) queries.
متن کاملThe Restricted and Bounded Fixpoint Closures of the Nested Algebra are Equivalent
The nested model is an extension of the traditional, “flat” relational model in which relations can also have relationvalued entries. Its “default” query language, the nested algebra, is rather weak, unfortunately, since it is only a conservative extension of the traditional, “flat” relational algebra, and thus can only express a small fraction of the polynomial-time queries. Therefore, it was ...
متن کاملThe Generalized Counting Method for Recursive Logic Queries
This paper treats the problem of implementing efficiently recursive Horn Clauses queries, including those with function symbols. In particular, the situation is studied where the initial bindings of the arguments in the recursive query goal can be used in the top-down (as in backward chaining) execution phase to improve the efficiency and, often, to guarantee the termination, of the forward cha...
متن کاملA More Expressive Deterministic Query Language with Efficient Symmetry-Based Choice Construct
In this paper, symmetry-based choice mechanisms are exploited to compute deterministic queries. We investigate a particular form of these choice mechanisms, called specified symmetry choice. This mechanism is efficient (i.e. computable in polynomial time) and can be added to Fixpoint Logic to give a language that is more powerful than the extension of Fixpoint with Counting.
متن کاملTowards Formal Foundations of Event Queries and Rules
The field of complex event processing still lacks formal foundations. In particular, event queries require both declarative and operational semantics. We put forward for discussion a proposal towards formal foundations of event queries that aims at making well-known results from database queries applicable to event queries. Declarative semantics of event queries and rules are given as a model t...
متن کامل