Logic & Formal Reasoning
Social choice rules driven by propositional logic
Camps, Rosa, Mora, Xavier, Saumell, Laia
Several rules for social choice are examined from a unifying point of view that looks at them as procedures for revising a system of degrees of belief in accordance with certain specified logical constraints. Belief is here a social attribute, its degrees being measured by the fraction of people who share a given opinion. Different known rules and some new ones are obtained depending on which particular constraints are assumed. These constraints allow to model different notions of choiceness. In particular, we give a new method to deal with approval-disapproval-preferential voting.
Logic of temporal attribute implications
We study logic for reasoning with if-then formulas describing dependencies between attributes of objects which are observed in consecutive points in time. We introduce semantic entailment of the formulas, show its fixed-point characterization, investigate closure properties of model classes, present an axiomatization and prove its completeness, and investigate alternative axiomatizations and normalized proofs. We investigate decidability and complexity issues of the logic and prove that the entailment problem is NP-hard and belongs to EXPSPACE. We show that by restricting to predictive formulas, the entailment problem is decidable in pseudo-linear time.
Distributed Evaluation of Nonmonotonic Multi-context Systems
Dao-Tran, Minh, Eiter, Thomas, Fink, Michael, Krennwallner, Thomas
Multi-context Systems (MCSs) are a formalism for systems consisting of knowledge bases (possibly heterogeneous and non-monotonic) that are interlinked via bridge rules, where the global system semantics emerges from the local semantics of the knowledge bases (also called contexts) in an equilibrium. While MCSs and related formalisms are inherently targeted for distributed set- tings, no truly distributed algorithms for their evaluation were available. We address this short- coming and present a suite of such algorithms which includes a basic algorithm DMCS, an ad- vanced version DMCSOPT that exploits topology-based optimizations, and a streaming algorithm DMCS-STREAMING that computes equilibria in packages of bounded size. The algorithms be- have quite differently in several respects, as experienced in thorough experimental evaluation of a system prototype. From the experimental results, we derive a guideline for choosing the appropriate algorithm and running mode in particular situations, determined by the parameter settings.
FIFTH system for general-purpose connectionist computation
To date, work on formalizing connectionist computation in a way that is at least Turing-complete has focused on recurrent architectures and developed equivalences to Turing machines or similar super-Turing models, which are of more theoretical than practical significance. We instead develop connectionist computation within the framework of information propagation networks extended with unbounded recursion, which is related to constraint logic programming and is more declarative than the semantics typically used in practical programming, but is still formally known to be Turing-complete. This approach yields contributions to the theory and practice of both connectionist computation and programming languages. Connectionist computations are carried out in a way that lets them communicate with, and be understood and interrogated directly in terms of the high-level semantics of a general-purpose programming language. Meanwhile, difficult (unbounded-dimension, NP-hard) search problems in programming that have previously been left to the programmer to solve in a heuristic, domain-specific way are solved uniformly a priori in a way that approximately achieves information-theoretic limits on performance.
A Situation-Calculus Based Theory of Justified Knowledge and Action
Scherl, Richard (Monmouth University)
This paper proposes an integration of the situation calculus with justification logic. Justification logic can be seen as a refinement of a modal logic of knowledge and belief to one in which knowledge not only is something that holds in all possible worlds, but also is justified. The work is an extension of that of Scherl and Levesque's integration of the situation calculus with a modal logic of knowledge. We show that the solution developed here retains all of the desirable properties of the earlier solution while incorporating the enhanced expressibility of having justifications.
A Probabilistic Extension of the Stable Model Semantics
Lee, Joohyung (Arizona State University) | Wang, Yi (Arizona State University)
We present a probabilistic extension of logic programs under the stable model semantics, inspired by the idea of Markov Logic Networks. The proposed language, called LP MLN , is a generalization of logic programs under the stable model semantics, and as such, embraces the rich body of research in knowledge representation. The language is also a generalization of ProbLog, and is closely related to Markov Logic Networks, which implies that the computation can be carried out by the techniques developed for them. LP MLN appears to be a natural language for probabilistic answer set programming, and as an example we show how an elaboration tolerant representation of transition systems in answer set programs can be naturally extended to the probabilistic setting.
A CLIB-Inspired Library of Commonsense Knowledge in Modular Action Language ALM
Inclezan, Daniela (Miami University)
This paper describes a modular action language, ALM, dedicated to the specification of complex dynamic systems. One of the main goals of the language is to facilitate the development and testing of knowledge representation libraries. We present the implementation of a large scale library of commonsense concepts, achieved by porting knowledge from the Component Library (CLIB) into ALM. Our choice of CLIB as a source of inspiration is justified by the well-founded methodology used by its authors in selecting the general concepts it contains, and its extensive testing in the context of the Automated User-centered Reasoning and Acquisition System. The resulting ALM library has the additional advantage of incorporating established knowledge representation methodologies developed in the action language research community.
Languages for Learning and Mining
However, it is well-known that applying machine learning and data mining to novel data sets is Finally, inspired by the field of constraint programming, challenging because each application imposes its own requirements (Guns et al. 2013) aim at developing declarative modeling and constraints that often require the development languages for specifying a wide range of mining problems. of new algorithms and systems. While there are software Such languages should support packages and tools such as Scikit for machine learning the high-level and natural modeling of pattern mining and Weka, Orange or Knime for data mining, adapting them tasks; that is, the models should closely correspond to to novel tasks is not easy, which explains why one often resorts the definitions of data mining problems found in the to implementing new algorithms and variations from literature; should support user-defined constraints and scratch.
What's Hot in the SAT and ASP Competitions
Heule, Marijn (The University of Texas at Austin) | Schaub, Torsten (University of Potsdam)
Some solvers, such as lingeling, use techniques The SAT Competitions, organized since 2002, have been the that cannot be expressed using resolution and cannot driving force of SAT solver development. The performance be expressed in the SAT Competition 2013 formats. of contemporary SAT solvers is incomparable to those of a One technique that cannot be expressed using resolution, decade ago. As a consequence, SAT solvers are used as the but is used in some top solvers, is bounded variable addition core search engine in many utilities, including tools for hardware (Manthey, Heule, and Biere 2013).
SMT-Based Validation of Timed Failure Propagation Graphs
Bozzano, Marco (Fondazione Bruno Kessler) | Cimatti, Alessandro (Fondazione Bruno Kessler) | Gario, Marco (Fondazione Bruno Kessler) | Micheli, Andrea (Fondazione Bruno Kessler)
Timed Failure Propagation Graphs (TFPGs) are a formalism used in industry to describe failure propagation in a dynamic partially observable system. TFPGs are commonly used to perform model-based diagnosis. As in any model-based diagnosis approach, however, the quality of the diagnosis strongly depends on the quality of the model. Approaches to certify the quality of the TFPG are limited and mainly rely on testing. In this work we address this problem by leveraging efficient Satisfiability Modulo Theories (SMT) engines to perform exhaustive reasoning on TFPGs. We apply model-checking techniques to certify that a given TFPG satisfies (or not) a property of interest. Moreover, we discuss the problem of refinement and diagnosability testing and empirically show that our technique can be used to efficiently solve them.