Complexity of Existential Positive First-Order Logic
نویسندگان
چکیده
Let Γ be a (not necessarily finite) structure with a finite relational signature. We prove that deciding whether a given existential positive sentence holds in Γ is in LOGSPACE or complete for the class CSP(Γ )NP under deterministic polynomial-time many-one reductions. Here, CSP(Γ )NP is the class of problems that can be reduced to the constraint satisfaction problem of Γ under non-deterministic polynomial-time many-one reductions.
منابع مشابه
How Many Variables Are Needed to Express an Existential Positive Query?
The number of variables used by a first-order query is a fundamental measure which has been studied in numerous contexts, and which is known to be highly relevant to the task of query evaluation. In this article, we study this measure in the context of existential positive queries. Building on previous work, we present a combinatorial quantity defined on existential positive queries; we show th...
متن کاملDichotomies and Duality in First-order Model Checking Problems
We study the complexity of the model checking problem, for fixed model A, over certain fragments L of first-order logic. These are sometimes known as the expression complexities of L. We obtain various complexity classification theorems for these logics L as each ranges over models A, in the spirit of the dichotomy conjecture for the Constraint Satisfaction Problem – which itself may be seen as...
متن کاملOn the complexity of fragments of second-order logic
Existential second order logic (ESO) is an extension of first-order logic (FO) that allows the existential quantification of relation and function symbols. The seminal result due to Fagin states that the properties expressible in ESO coincide with the decision problems in the complexity class NP. On the other hand, the monadic fragment of ESO is considerably weaker as it corresponds to the clas...
متن کاملSecond-Order Logic over Finite Structures - Report on a Research Programme
This talk will report on the results achieved so far in the context of a research programme at the cutting point of logic, formal language theory, and complexity theory. The aim of this research programme is to classify the complexity of evaluating formulas from different prefix classes of second-order logic over different types of finite structures, such as strings, graphs, or arbitrary struct...
متن کاملAcyclic Query Answering under Guarded Disjunctive Existential Rules and Consequences to DLs
The complete picture of the complexity of conjunctive query answering under guarded disjunctive existential rules has been recently settled. However, in the case of (unions of) acyclic conjunctive queries ((U)ACQs) there are some fundamental questions which are still open. It is the precise aim of the present paper to close those questions, and to understand whether the acyclicity of the query ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- J. Log. Comput.
دوره 23 شماره
صفحات -
تاریخ انتشار 2009