@article {van2013preferential, title = {Preferential Semantics using Non-smooth Preference Relations}, journal = {Journal of Philosophical Logic}, volume = {43}, number = {5}, year = {2013}, pages = {903{\textendash}942}, abstract = {

This paper studies the properties of eight semantic consequence relations defined from a Tarski-logic L and a preference relation \&\#8826;. They are equivalent to ShohamÂ’s so-called preferential entailment for smooth model structures, but avoid certain problems of the latter in non-smooth configurations. Each of the logics can be characterized in terms of what we call multi-selection semantics. After discussing this type of semantics, we focus on some concrete proposals from the literature, checking a number of meta-theoretic properties and elaborating on their intuitive motivation. As it turns out, many of their meta-properties only hold in case \&\#8826; is transitive. To tackle this problem, we propose slight modifications of each of the systems, showing the resulting logics to behave better at the intuitive level and in metatheoretic terms, for arbitrary \&\#8826;.

}, author = {Van De Putte, Frederik and Stra{\ss}er, Christian} } @article {Strasser2012, title = {Proof Theories for Superpositions of Adaptive Logics}, journal = {Logique et Analyse}, year = {2012}, pages = {1{\textendash}33}, abstract = {

The standard format for adaptive logics offers a generic and unifying formal framework for defeasible reasoning forms. One of its main distinguishing features is a dynamic proof theory by means of which it is able to explicate actual reasoning. In many applications it has proven very useful to superpose sequences of adaptive logics, such that each logic treats the consequence set of its predecessor as premise set. Although attempts have been made to define dynamic proof theories for some of the resulting logics, no generic proof theory is available yet. Moreover, the existing proof theories for concrete superpositions are suboptimal in various respects: the derivability relations characterized by these proposals are often not adequate with respect to the consequence relation of the superposed adaptive logics and in some cases they even trivialize premise sets. An adequate and generic proof theory is needed in order to meet the requirement of explicating defeasible reasoning in terms of superpositions of adaptive logics. This paper presents two generic proof theories for superpositions of adaptive logics in standard format. By means of simple examples, the basic ideas behind these proof theories are illustrated and it is shown how the older proposals are inadequate.

}, author = {Stra{\ss}er, Christian and Van De Putte, Frederik} } @proceedings {1861627, title = {A paraconsistent multi-agent framework for dealing with normative conflicts}, journal = {12th International Workshop on Computational Logic in Multi-Agent Systems (CLIMA XII)}, year = {2011}, pages = {312-329}, publisher = {Springer}, abstract = {

In a multi-agent deontic setting, normative conflicts can take a variety of different logical forms. In this paper, we present a very general characterization of such conflicts, including both intra- and inter-agent normative conflicts, conflicts between groups of agents, conflicts between obligations and permissions, and conflicts between contradictory norms. In order to account for the consistent possibility of this wide variety of conflict-types, we present a paraconsistent deontic logic, i.e. a logic that invalidates the classical principle of non-contradiction. Next, we strengthen this logic within the adaptive logics framework for defeasible reasoning. The resulting inconsistency-adaptive deontic logic interprets a given set of norms {\textquoteright}as consistently as possible{\textquoteright}.

}, isbn = {9783642223587}, url = {http://dx.doi.org/10.1007/978-3-642-22359-4}, author = {Beirlaen, Mathieu and Stra{\ss}er, Christian}, editor = {Leite, Joao and Torroni, Paolo and Agotnes, Thomas and Boella, Guido and van der Torre, Leon} }