Results 1  10
of
29
A constraintbased approach to guarded algebraic data types
 ACM Trans. Prog. Languages Systems
, 2007
"... We study HMG(X), an extension of the constraintbased type system HM(X) with deep pattern matching, polymorphic recursion, and guarded algebraic data types. Guarded algebraic data types subsume the concepts known in the literature as indexed types, guarded recursive datatype constructors, (firstcla ..."
Abstract

Cited by 27 (0 self)
 Add to MetaCart
(Show Context)
We study HMG(X), an extension of the constraintbased type system HM(X) with deep pattern matching, polymorphic recursion, and guarded algebraic data types. Guarded algebraic data types subsume the concepts known in the literature as indexed types, guarded recursive datatype constructors, (firstclass) phantom types, and equality qualified types, and are closely related to inductive types. Their characteristic property is to allow every branch of a case construct to be typechecked under different assumptions about the type variables in scope. We prove that HMG(X) is sound and that, provided recursive definitions carry a type annotation, type inference can be reduced to constraint solving. Constraint solving is decidable, at least for some instances of X, but prohibitively expensive. Effective type inference for guarded algebraic data types is left as an issue for future research.
ConstraintBased Type Inference for Guarded Algebraic Data Types
, 2003
"... Guarded algebraic data types, which subsume the concepts known in the literature as indexed types, guarded recursive datatype constructors, and phantom types, and are closely related to inductive types, have the distinguishing feature that, when typechecking a function defined by cases, every branch ..."
Abstract

Cited by 24 (3 self)
 Add to MetaCart
(Show Context)
Guarded algebraic data types, which subsume the concepts known in the literature as indexed types, guarded recursive datatype constructors, and phantom types, and are closely related to inductive types, have the distinguishing feature that, when typechecking a function defined by cases, every branch must be checked under di#erent typing assumptions. This mechanism allows exploiting the presence of dynamic tests in the code to produce extra static type information.
The FirstOrder Theory of Ordering Constraints over Feature Trees
 Discrete Mathematics and Theoretical Computer Science
, 2001
"... The system FT of ordering constraints over feature trees has been introduced as an extension of the system FT of equality constraints over feature trees. We investigate the firstorder theory of FT and its fragments, both over finite trees and over possibly infinite trees. We prove that the firstor ..."
Abstract

Cited by 19 (6 self)
 Add to MetaCart
(Show Context)
The system FT of ordering constraints over feature trees has been introduced as an extension of the system FT of equality constraints over feature trees. We investigate the firstorder theory of FT and its fragments, both over finite trees and over possibly infinite trees. We prove that the firstorder theory of FT is undecidable, in contrast to the firstorder theory of FT which is wellknown to be decidable. We determine the complexity of the entailment problem of FT with existential quantification to be PSPACEcomplete, by proving its equivalence to the inclusion problem of nondeterministic finite automata. Our reduction from the entailment problem to the inclusion problem is based on a new alogrithm that, given an existential formula of FT , computes a finite automaton which accepts all its logic consequences.
Complexity of Nonrecursive Logic Programs with Complex Values
 In Proceedings of the 17th ACM SIGACTSIGMODSIGART Symposium on Principles of Database Systems (PODS’98
, 1998
"... We investigate complexity of the SUCCESS problem for logic query languages with complex values: check whether a query defines a nonempty set. The SUCCESS problem for recursive query languages with complex values is undecidable, so we study the complexity of nonrecursive queries. By complex values we ..."
Abstract

Cited by 16 (2 self)
 Add to MetaCart
(Show Context)
We investigate complexity of the SUCCESS problem for logic query languages with complex values: check whether a query defines a nonempty set. The SUCCESS problem for recursive query languages with complex values is undecidable, so we study the complexity of nonrecursive queries. By complex values we understand values such as trees, finite sets, and multisets. Due to the wellknown correspondence between relational query languages and datalog, our results can be considered as results about relational query languages with complex values. The paper gives a complete complexity classification of the SUCCESS problem for nonrecursive logic programs over trees depending on the underlying signature, presence of negation, and range restrictedness. We also prove several results about finite sets and multisets. 1 Introduction A number of complexity results have been established for logic query languages. They are surveyed in [49, 18]. The major themes in these results are the complexity and expr...
Destabilizers and Independence of XML Updates
"... Independence analysis is the problem of determining whether an update affects the result of a query, e.g. a constraint or materialized view. We develop a new, modular framework for static independence analysis that decomposes the problem into two orthogonal subproblems: approximating the destabilize ..."
Abstract

Cited by 14 (1 self)
 Add to MetaCart
(Show Context)
Independence analysis is the problem of determining whether an update affects the result of a query, e.g. a constraint or materialized view. We develop a new, modular framework for static independence analysis that decomposes the problem into two orthogonal subproblems: approximating the destabilizer, that is, a finite representation of the set of updates that can change the result of the query, and testing whether the update and destabilizer overlap via an intersection analysis. Focusing on XML queries as the view language and the XQuery Update Facility as the update language, we present a syntactic query rewriting algorithm for translating queries to destabilizers, and show that intersection checking can be reduced to satisfiability problems for which efficient checkers already exist. We present an implementation based on an expressive tree satisfiability checker and a Satisfiability Modulo Order package, and give experiments confirming that the resulting analysis is both fast and effective. 1.
Term algebras with length function and bounded quantifier alternation
 In Theorem Proving in HigherOrder Logics, volume 3223 of LNCS
, 2004
"... .)L: TA! Z. Formulae are formed from term literals and integerliterals using logical connectives and quantifications. Term literals are exactly ..."
Abstract

Cited by 12 (5 self)
 Add to MetaCart
(Show Context)
.)L: TA! Z. Formulae are formed from term literals and integerliterals using logical connectives and quantifications. Term literals are exactly
SchemaBased Independence Analysis for XML Updates
"... Queryupdate independence analysis is the problem of determining whether an update affects the results of a query. Queryupdate independence is useful for avoiding recomputation of materialized views and may have applications to access control and concurrency control. This paper develops static anal ..."
Abstract

Cited by 11 (2 self)
 Add to MetaCart
(Show Context)
Queryupdate independence analysis is the problem of determining whether an update affects the results of a query. Queryupdate independence is useful for avoiding recomputation of materialized views and may have applications to access control and concurrency control. This paper develops static analysis techniques for queryupdate independence problems involving core XQuery queries and updates with a snapshot semantics (based on the W3C XQuery Update Facility proposal). Our approach takes advantage of schema information, in contrast to previous work on this problem. We formalize our approach, sketch a proof of correctness, and report on the performance and accuracy of our implementation. 1.
LISA: A Specification Language Based on WS2S
, 1998
"... We integrate two concepts from programming languages into a specification language based on WS2S, namely highlevel data structures such as records and recursivelydefined datatypes (WS2S is the weak secondorder monadic logic of two successors). Our integration is based on a new logic whose variabl ..."
Abstract

Cited by 10 (1 self)
 Add to MetaCart
We integrate two concepts from programming languages into a specification language based on WS2S, namely highlevel data structures such as records and recursivelydefined datatypes (WS2S is the weak secondorder monadic logic of two successors). Our integration is based on a new logic whose variables range over recordlike trees and an algorithm for translating datatypes into tree automata. We have implemented LISA, a prototype system based on these ideas, which, when coupled with a decision procedure for WS2S like the MONA system, results in a verification tool that supports both highlevel specifications and complexity estimations for the running time of the decision procedure.
Computing Nonground Representations of Stable Models
 Proceedings of the 4th International Conference on Logic Programming and Nonmonotonic Reasoning (LPNMR97), number 1265 in Lecture Notes in Computer Science
, 1997
"... Turi [20] introduced the important notion of a constrained atom: an atom with associated equality and disequality constraints on its arguments. A set of constrained atoms is a constrained interpretation. ..."
Abstract

Cited by 9 (0 self)
 Add to MetaCart
Turi [20] introduced the important notion of a constrained atom: an atom with associated equality and disequality constraints on its arguments. A set of constrained atoms is a constrained interpretation.