scholarly journals Variational and quasivariational inequalities with first order constraints

2013 ◽  
Vol 397 (2) ◽  
pp. 738-756 ◽  
Author(s):  
Assis Azevedo ◽  
Fernando Miranda ◽  
Lisa Santos
Keyword(s):  
Quasivariational Inequalities ◽  
First Order ◽  
Order Constraints

scholarly journals An Interpolation-based Compiler and Optimizer for Relational Queries (System design Report)

10.29007/53fk ◽  
2018 ◽  
Author(s):  
David Toman ◽  
Grant Weddell
Keyword(s):  
System Design ◽  
Cost Model ◽  
Interpolation Theorem ◽  
Database Schema ◽  
External Cost ◽  
First Order ◽  
User Query ◽  
Order Constraints ◽  
Proof Procedure ◽  
Distinguished Subset

We outline the implementation of a query compiler for relational queries that generates query plans with respect to a database schema, that is, a set of arbitrary first-order constraints, and a distinguished subset of predicate symbols from the underlying signature that correspond to access paths. The compiler is based on a variant of the Craig interpolation theorem, with reasoning realized via a modified analytic tableau proof procedure. This procedure decouples the generation of candidate plans that are interpolants from the tableau proof procedure, and applies A*-based search with respect to an external cost model to arbitrate among the alternative candidate plans. The tableau procedure itself is implemented as a virtual machine that operates on a compiled and optimized byte-code that faithfully implements reasoning with respect to the database schema constraints and a user query.

scholarly journals Finite Controllability for Ontology-Mediated Query Answering of CRPQ

2020 ◽  
Author(s):  
Diego Figueira ◽  
Santiago Figueira ◽  
Edwin Pin Baque
Keyword(s):  
Query Answering ◽  
Graph Structure ◽  
First Order ◽  
Underlying Graph ◽  
Graph Classes ◽  
Regular Path ◽  
Order Constraints ◽  
Simple Recursion ◽  
Regular Path Queries ◽  
Path Queries

Finite ontology mediated query answering (FOMQA) is the variant of ontology mediated query answering (OMQA) where the represented world is assumed to be finite, and thus only finite models of the ontology are considered. We study the property of finite-controllability, that is, whether FOMQA and OMQA are equivalent, for fragments of C2RPQ. C2RPQ is the language of conjunctive two-way regular path queries, which can be regarded as the result of adding simple recursion to Conjunctive Queries. For graph classes S, we consider fragments C2RPQ(S) of C2RPQ as the queries whose underlying graph structure is in S. We completely classify the finitely controllable and non-finitely controllable fragments under: inclusion dependencies, (frontier-)guarded rules, frontier-one rules (either with or without constants), and more generally under guarded-negation first-order constraints. For the finitely controllable fragments, we show a reduction to the satisfiability problem for guarded-negation first-order logic, yielding a 2EXPTIME algorithm (in combined complexity) for the corresponding (F)OMQA problem.

Rules, Defeasibility, and the Psychology of Exceptions

2020 ◽  
pp. 55-64
Author(s):  
Frederick Schauer
Keyword(s):  
Social Psychology ◽  
International Law ◽  
Experimental Research ◽  
Second Order ◽  
Decision Makers ◽  
First Order ◽  
Order Constraints ◽  
Domestic Law

An important aspect of international law is that it typically lacks the formal, structured, and institutional enforcement and sanctioning mechanisms of domestic law. As a result, decision-makers constrained by international law are often faced with applying the rules of international law to their own action. We know from H.L.A. Hart and others that such internalization is possible, but we know from a great deal of experimental research in cognitive and social psychology that imposing second-order constraints on one’s first-order preferences is difficult and rare without a sanctioning mechanism. As a result, there exists a serious risk that treating the rules of international law as defeasible and subject to exceptions will render the constraints of international law ineffectual when actors are making the decisions about whether and when the exceptions to constraining rules apply to their own actions.

Computational Reference Dynamical Model of a Multibody System With First Order Constraints

2017 ◽  
Author(s):  
Elżbieta Jarzębowska ◽  
Krzysztof Augustynek ◽  
Andrzej Urbaś
Keyword(s):  
Equations Of Motion ◽  
Computational Procedure ◽  
Dynamical Models ◽  
Constrained System ◽  
First Order ◽  
Performance Requirements ◽  
Control Goal ◽  
Order Constraints ◽  
Reaction Forces ◽  
And Control

The paper presents a development of a computational based procedure for generation of constrained system dynamical models. The constraints may be both holonomic and first order nonholonomic, either material or nonmaterial. The latter ones are referred to as programmed and they are imposed by a designer, a control engineer as a control goal, or may come from controlled system performance requirements. The procedure for generation of constrained dynamics provides then reference dynamical models, i.e. models whose solutions satisfy all the constraints put upon them. These models may serve as motion planners for control. The distinctions between the presented approach and the ones reported in the literature are that the constraints may be material or nonmaterial and the final equations of motion are derived in the reduced state form, i.e. constraint reaction forces are eliminated at the equations derivation level but not afterwards as in the case of the Lagrange approach. This is the essential advantage of our approach and this one computational procedure may serve both reference and control oriented dynamical models derivation. The procedure is applied to a manipulator model whose end effector is subjected to a programmed constrained.

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