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About 545 papers for “Existential quantification”

Temporal Datalog with Existential Quantification

Matthias Lanzinger, Markus Nissl, Emanuel Sallinger et al. · 2023

Existential rules, also known as tuple-generating dependencies (TGDs) or Datalog+/- rules, are heavily studied in the communities of Knowledge Representation and Reasoning, Semantic Web, and Databases, due to their rich modelling capabilities. In this paper we consider TGDs in the temporal setting, by introducing and studying DatalogMTLE---an extension of metric temporal Datalog (DatalogMTL) obtained by allowing for existential rules in programs. We show that DatalogMTLE is undecidable even in the restricted cases of guarded and weakly-acyclic programs. To address this issue we introduce uniform semantics which, on the one hand, is well-suited for modelling temporal knowledge as it prevents from unintended value invention and, on the other hand, provides decidability of reasoning; in particular, it becomes 2-EXPSPACE-complete for weakly-acyclic programs but remains undecidable for guarded programs. We provide an implementation for the decidable case and demonstrate its practical feasibility. Thus we obtain an expressive, yet decidable, rule-language and a system which is suitable for complex temporal reasoning with existential rules.

Cited by 0Open access

Extending Existential Quantification in Conjunctions of BDDs

Sean Weaver, John Franco, John S. Schlipf · Journal on Satisfiability Boolean Modeling and Computation · 2006

We introduce new approaches intended to speed up determining the satisfiability of a given Boolean formula expressed as a conjunction of Boolean functions. A common practice in such cases, when using constraint-oriented methods, is to represent the functions as BDDs, then repeatedly cluster BDDs containing one or more variables, and finally existentially quantify those variables away from the cluster. Clustering is essential because, in general, existential quantification cannot be applied unless the variables occur in only a single BDD. But, clustering incurs significant overhead and may result in BDDs that are too big to allow the process to complete in a reasonable amount of time.

Cited by 15Open access

Existential quantification in Tiwa: disjunction and indefinites

Virginia Ellen Dawson · eScholarship (California Digital Library) · 2020

This dissertation examines the semantics and pragmatics of disjunction and indefinites in Tiwa, an understudied Tibeto-Burman language of northeast India. The core focus of the dissertation concerns cross-linguistic variation and its implications for semantic theory. Broadly, I address the extent to which languages encode similar meanings through the same semantic means; what mechanisms are best suited to model those meanings; and how the theory can best model what cross-linguistic variation we do find. Concretely, I provide novel cross-linguistic evidence from phrasal comparatives that disjunction is alternative-denoting, and argue that languages can employ different semantic mechanisms in deriving exceptional wide scope.Tiwa's large system of indefinites and disjunction particles, which are in part morphologically related, provide an ideal subject for exploring the logical connection between disjunction and indefinites (which amount to existential quantification over explicit and non-explicit domains respectively). While cross-linguistic studies of indefinites have seen an increase in recent years, disjunction has not received the same level of attention. In this dissertation, I provide a detailed description of the semantic and pragmatic behavior of Tiwa's various disjunction particles and their related indefinites, which, among other things, explicitly encode scope. Additionally, the dissertation contains a broader sketch of Tiwa grammar as a whole, which provides documentation and formal description of many aspects of the language. This empirical contribution is the result of original fieldwork in Assam, India, over the course of four years.

Cited by 6Open access

Virginia Dawson: Existential Quantification in Tiwa: Disjunction and Indefinites

Dawson, Virginia, Clem, Emily, Dabkowski, Maksymilian et al. · California Digital Library · 2020

PhD candidate: Dawson; PhD dissertation committee: Deal (chair), Jenks, Mikkelsen, Yalcin (external member). Other individuals labeled as participants asked questions. The defense was held on Zoom due to COVID-19. There is a single video file that includes the research presentation, questions from the committee, then questions from the audience. One .pdf file consists of slides of the research presentation.

Cited by 0Open access

A Flexible Framework for Type Inference with Existential Quantification

Ross Tate, Juan Chen, Chris Hawblitzel · 2008

Abstract. Preserving types through compilation guarantees safety of the compiler output without trusting the compiler: the compiler output is annotated with types and can be verified. Type inference can make this technique more practical by inferring most of the needed type infor-mation. Existential types, however, are difficult to infer, especially those with implicit pack and unpack operations. This paper proposes a framework for type inference with existential quan-tification and demonstrates the framework on a small object-oriented typed assembly language. The framework is flexible enough to support language features such as downward casts, arrays, and interfaces. The framework is based on category theory, the first such application of cat-egory theory to type inference to the best of our knowledge. 1

Cited by 2

Inner approximation of distance constraints with existential quantification of parameters

Carlos Grandón, Alexandre Goldsztejn · 2006

This paper presents and compares two methods for checking if a box is included inside the solution set of an equality constraint with existential quantification of its parameters. We focus on distance constraints, where each existentially quantified parameter has only one occurrence, because of their usefulness and their simplicity. The first method relies on a specific quantifier elimination based on geometric considerations whereas the second method relies on computations with generalized intervals (interval whose bounds are not constrained to be ordered). We show that on two dimensions problems, the two methods yield equivalent results. However, when dealing with higher dimensions, generalized intervals are more efficient.

Cited by 2

Inner Approximation of Distance Constraints with Existential Quantification of Parameters

Alexandre Goldsztejn · 2015

This paper presents and compares two methods for checking if a box is included inside the solution set of an equality con-straint with existential quantification of its parameters. We focus on distance constraints, where each existentially quan-tified parameter has only one occurrence, because of their usefulness and their simplicity. The first method relies on a specific quantifier elimination based on geometric consid-erations whereas the second method relies on computations with generalized intervals (interval whose bounds are not constrained to be ordered). We show that on two dimen-sions problems, the two methods yield equivalent results. However, when dealing with higher dimensions, generalized intervals are more efficient.

Cited by 0

Augmenting branching temporal logics with existential quantification over atomic propositions

Orna Kupferman · Journal of Logic and Computation · 1999

In temporal-logic model checking, we verify the correctness of a program with respect to a desired behaviour by checking whether a structure that models the program satisfies a temporal logic formula that specifies this s behaviour. One of the ways to overcome the expressiveness limitation of temporal logics is to augment them with quantification over atomic propositions. In this paper we consider the extension of branching temporal logics with existential quantification over atomic propositions. Once we add existential quantification to a branching temporal logic, it becomes sensitive to unwinding. That is, unwinding a structure into an infinite tree does not preserve the set of formulas it satisfies. Accordingly, we distinguish between two semantics, two practices as specification languages, and two versions of the model-checking problem for such a logic. One semantics refers to the structure that models the program, and the second semantics refers to the infinite computation tree that the program induces. We examine the complexity of the model-checking problem in the two semantics for the logics CTL and CTL* augmented with existential quantification over atomic propositions. Following the cheerless results that we get, we examine also the program complexity of model checking; i.e. the complexity of this problem in terms of the program, assuming the formula is fixed. We show that while fixing the formula dramatically reduces model-checking complexity in the tree semantics its influence on the structure semantics is poor.

Cited by 29

Inner Approximation of Distance Constraints with Existential Quantification of Parameters

2008

We present and compare two methods for checking if a box is included inside the solution set of an equality constraint with existential quantification of its parameters. We focus on distance constraints, where each existentially quantified parameter has only one ocurrence. The first method relies on a Specific Quantifier Elimination (SQE) algorithm based on geometric consideration whereas the second method relies on computations with Generalized Intervals Evaluation (GIE).

Cited by 0

Kappa-Join: Efficient Execution of Existential Quantification in XML Query Languages

Reihe Informatik, M. Brantner, S. Helmer et al. · 2008

Abstract. XML query languages feature powerful primitives for formulating queries involving comparison expressions which are existentially quantified. If such comparisons involve several scopes, they are correlated, and become difficult to evaluate efficiently. In this paper, we develop a new ternary operator, called Kappa-Join, for efficiently evaluating queries with existential quantification. In XML queries, a correlation predicate can occur conjunctively and disjunctively. Our decorrelation approach not only improves performance in the conjunctive case, but also allows decorrelation of the disjunctive case. The latter is not possible with any known technique. In an experimental evaluation, we compare the query execution times of the Kappa-Join with existing XPath evaluation techniques to demonstrate the effectiveness of our new operator. 1

Cited by 0