62,971 research outputs found
A Cut-Free Sequent Calculus for Defeasible Erotetic Inferences
In recent years, the effort to formalize erotetic inferences (i.e., inferences
to and from questions) has become a central concern for those working
in erotetic logic. However, few have sought to formulate a proof theory
for these inferences. To fill this lacuna, we construct a calculus for (classes
of) sequents that are sound and complete for two species of erotetic inferences
studied by Inferential Erotetic Logic (IEL): erotetic evocation and regular erotetic implication. While an attempt has been made to axiomatize the former in a sequent
system, there is currently no proof theory for the latter. Moreover, the extant
axiomatization of erotetic evocation fails to capture its defeasible character
and provides no rules for introducing or eliminating question-forming operators.
In contrast, our calculus encodes defeasibility conditions on sequents and
provides rules governing the introduction and elimination of erotetic formulas.
We demonstrate that an elimination theorem holds for a version of the cut
rule that applies to both declarative and erotetic formulas and that the rules
for the axiomatic account of question evocation in IEL are admissible in our
system
Theorem proving support in programming language semantics
We describe several views of the semantics of a simple programming language
as formal documents in the calculus of inductive constructions that can be
verified by the Coq proof system. Covered aspects are natural semantics,
denotational semantics, axiomatic semantics, and abstract interpretation.
Descriptions as recursive functions are also provided whenever suitable, thus
yielding a a verification condition generator and a static analyser that can be
run inside the theorem prover for use in reflective proofs. Extraction of an
interpreter from the denotational semantics is also described. All different
aspects are formally proved sound with respect to the natural semantics
specification.Comment: Propos\'e pour publication dans l'ouvrage \`a la m\'emoire de Gilles
Kah
Automated Synthesis of Tableau Calculi
This paper presents a method for synthesising sound and complete tableau
calculi. Given a specification of the formal semantics of a logic, the method
generates a set of tableau inference rules that can then be used to reason
within the logic. The method guarantees that the generated rules form a
calculus which is sound and constructively complete. If the logic can be shown
to admit finite filtration with respect to a well-defined first-order semantics
then adding a general blocking mechanism provides a terminating tableau
calculus. The process of generating tableau rules can be completely automated
and produces, together with the blocking mechanism, an automated procedure for
generating tableau decision procedures. For illustration we show the
workability of the approach for a description logic with transitive roles and
propositional intuitionistic logic.Comment: 32 page
From Cognition to Consciousness:\ud a discussion about learning, reality representation and decision making.
The scientific understanding of cognition and consciousness is currently hampered by the lack of rigorous and universally accepted definitions that permit comparative studies. This paper proposes new functional and un- ambiguous definitions for cognition and consciousness in order to provide clearly defined boundaries within which general theories of cognition and consciousness may be developed. The proposed definitions are built upon the construction and manipulation of reality representation, decision making and learning and are scoped in terms of an underlying logical structure. It is argued that the presentation of reality also necessitates the concept of ab- sence and the capacity to perform transitive inference. Explicit predictions relating to these new definitions, along with possible ways to test them, are also described and discussed
Evaluating Knowledge Representation and Reasoning Capabilites of Ontology Specification Languages
The interchange of ontologies across the World Wide Web (WWW) and the cooperation among heterogeneous agents placed on it is the main reason for the development of a new set of ontology specification languages, based on new web standards such as XML or RDF. These languages (SHOE, XOL, RDF, OIL, etc) aim to represent the knowledge contained in an ontology in a simple and human-readable way, as well as allow for the interchange of ontologies across the web. In this paper, we establish a common framework to compare the expressiveness of "traditional" ontology languages (Ontolingua, OKBC, OCML, FLogic, LOOM) and "web-based" ontology languages. As a result of this study, we conclude that different needs in KR and reasoning may exist in the building of an ontology-based application, and these needs must be evaluated in order to choose the most suitable ontology language(s)
Logics of Formal Inconsistency enriched with replacement: an algebraic and modal account
One of the most expected properties of a logical system is that it can be algebraizable, in the sense that an algebraic counterpart of the deductive machinery could be found. Since the inception of da Costa's paraconsistent calculi, an algebraic equivalent for such systems have been searched. It is known that these systems are non self-extensional (i.e., they do not satisfy the replacement property). More than this, they are not algebraizable in the sense of Blok-Pigozzi. The same negative results hold for several systems of the hierarchy of paraconsistent logics known as Logics of Formal Inconsistency (LFIs). Because of this, these logics are uniquely characterized by semantics of non-deterministic kind. This paper offers a solution for two open problems in the domain of paraconsistency, in particular connected to algebraization of LFIs, by obtaining several LFIs weaker than C1, each of one is algebraizable in the standard Lindenbaum-Tarski's sense by a suitable variety of Boolean algebras extended with operators. This means that such LFIs satisfy the replacement property. The weakest LFI satisfying replacement presented here is called RmbC, which is obtained from the basic LFI called mbC. Some axiomatic extensions of RmbC are also studied, and in addition a neighborhood semantics is defined for such systems. It is shown that RmbC can be defined within the minimal bimodal non-normal logic E+E defined by the fusion of the non-normal modal logic E with itself. Finally, the framework is extended to first-order languages. RQmbC, the quantified extension of RmbC, is shown to be sound and complete w.r.t. BALFI semantics
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