1. Although the idea of measuring inconsistency was proposed in Grant (1978), the subject gained interest in 2002 with the publication of a proposal for measuring inconsistency in propositional kno...

Consistency is one of the key concepts of logic; logicians have put a great deal of effort into proving the consistency of many logics. Understanding what causes inconsistency is also important; some logicians have developed paraconsistent logics that, unlike classical logics, allow some contradictions without making all formulas provable. Another direction of research studies inconsistency by measuring the amount of inconsistency of sets of formulas. While the initial attempt in 1978 was too ambitious in trying to do this for first-order (...) logic, this research got a substantial boost when an inconsistency measure was proposed for propositional logic in 2002. Since then, researchers in logic and artificial intelligence have made many interesting proposals and found related issues. Almost all of this work has been done for propositional logic. The purpose of this paper is to extend inconsistency measures to logics that also contain operators, such as modal operators. We use the terminology “generalized propositional logic” for such logics. We show how to extend propositional inconsistency measures to sets of formulas in any such generalized propositional logic. Examples are used to illustrate how various modal operators, including spatial and tense operators, fit into this framework. We also show that the addition of operators leads to a weak type of inconsistency. In all cases, the calculations for several inconsistency measures are given. (shrink)

The first mention of the concept of an inconsistency measure for sets of formulas in first-order logic was given in 1978, but that paper presented only classifications for them. The first actual inconsistency measure with a numerical value was given in 2002 for sets of formulas in propositional logic. Since that time, researchers in logic and AI have developed a substantial theory of inconsistency measures. While this is an interesting topic from the point of view of logic, an important motivation (...) for this work is also that some intelligent systems may encounter inconsistencies in their operation. This research deals primarily with propositional knowledge bases, that is, finite sets of propositional logic formulas. The goal of this paper is to extend the concept of inconsistency measure in a formal way to sets of formulas with the modal operators “necessarily” and “possibly” applied to propositional logic formulas. We use frames for the semantics, but in a way that is different from the way that frames are commonly used in modal logics, in order to facilitate measuring inconsistency. As a set of formulas may have different inconsistency measures for different frames, we define the concept of a standard frame that can be used for all finite sets of formulas in the language. We do this for two languages. The first language, AMPL, contains formulas where a prefix of operators is applied to a propositional logic formula. The second language, CMPL, adds connectives that can be applied to AMPL formulas in a limited way. We show how to extend propositional logic inconsistency measures to such sets of formulas. Finally, we define a new concept, weak inconsistency measure, and show how to compute it. (shrink)

Branching time logics have been studied in computer science since the 1980s primarily to model the tree of computations for discrete transition systems. Inconsistency measures for propositional log...

This paper starts the systematic study of inconsistency measures for propositional logics enriched with operators involving time. We use Prior’s operators for tense logic: H, G, P, and F; however, we apply different semantics to them. We define two logics. The first one, ATPL, allows formulas with the application of any of the four operators any number of times to propositional logic formulas. The semantics is given in terms of TPL structures. We then show how to measure the inconsistency of (...) a set of ATPL formulas using appropriately modified versions of standard inconsistency measures for propositional logic. Additionally, these new measures are checked for the satisfaction of various properties. We also investigate a new concept of inconsistency that cannot be defined for propositional logic. Then, ATPL is extended to CTPL by applying the propositional connectives to ATPL formulas and measuring inconsistency is extended to sets of CTPL formulas. (shrink)

As consistency is such an important topic in logic, researchers have for a long time investigated how to attain and maintain it. But consistency can also be studied from the point of view of its opposite, inconsistency. The problem with inconsistency in classical logic is that by the principle of explosion a single inconsistency leads to triviality. Paraconsistent logics were introduced to get around this problem by defining logics in such a way that the explosion principle does not apply to (...) them. Another approach stays in the classical framework and evaluates the amount of inconsistency in a set of formulas. The great bulk of this work has been done for propositional logic and presents many interesting issues about inconsistency. A previous paper introduced the concept of generalized propositional logic (GPL) to provide a uniform method for measuring inconsistency in logics that allow the application of unary operator pairs, such as for modality, time, and space, to propositional logic formulas. The universality of GPL manifests itself in the fact that such an operator pair is evaluated in a uniform manner across all such logics. The difference lies solely in the choice of a frame for each logic. But some logics also contain nonunary operators. For example, temporal logics typically contain a binary Until operator. The purpose of this paper is to show how to extend generalized propositional logic to extended generalized propositional logic (EGPL) by adding nonunary operator pairs and measure inconsistency in such logics. The universality of EGPL manifests itself in the fact that once the evaluation of the nonunary operators is given, it carries over to all such logics. For example, the temporal Until operator becomes applicable to modal logic. Furthermore, while relative inconsistency measures were previously considered for GPL, they are now extended to EGPL and a new approach removes an undesirable feature from the previous version. Also, this paper provides results about various properties of the new inconsistency measures. Many examples and explanations are given to illustrate the issues involving this extension. (shrink)

1. In this special issue of the Journal of Applied Non-Classical Logics, we aim to celebrate the recent retirement of Philippe Besnard as directeur de recherche in the Centre National de Recherche...

1. Real-world applications, such as monitoring urban wastewater networks, commonly process large volumes of multi-source, heterogeneous data to support reasoning, query answering and decision-makin...