<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kurtonina, Natasha</style></author><author><style face="normal" font="default" size="100%">De Rijke, Maarten</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Bisimulations for Temporal Logic</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Logic, Language and Information</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">definability</style></keyword><keyword><style  face="normal" font="default" size="100%">expressive power</style></keyword><keyword><style  face="normal" font="default" size="100%">modal and temporal logic</style></keyword><keyword><style  face="normal" font="default" size="100%">model theory</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1997</style></year></dates><number><style face="normal" font="default" size="100%">4</style></number><volume><style face="normal" font="default" size="100%">6</style></volume><pages><style face="normal" font="default" size="100%">403–425</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;We define bisimulations for temporal logic with Since and Until. This new notion is compared to existing notions of bisimulations, and then used to develop the basic model theory of temporal logic with Since and Until. Our results concern both invariance and definability. We conclude with a brief discussion of the wider applicability of our ideas.&lt;/p&gt;</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kurtonina, Natasha</style></author><author><style face="normal" font="default" size="100%">De Rijke, Maarten</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Simulating without negation.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of logic and computation</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">1997</style></year></dates><number><style face="normal" font="default" size="100%">4</style></number><volume><style face="normal" font="default" size="100%">7</style></volume><pages><style face="normal" font="default" size="100%">501–522</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Although negation-free languages are widely used in logic and computer science, relatively little is known about their expressive power. To address this issue we consider kinds of non-symmetric bisimulations called directed simulations, and use these to analyse the expressive power and model theory of negation-free modal and temporal languages. We first use them to obtain preservation, safety and definability results for a simple negation-free modal language. We then obtain analogous results for stronger negation-free languages. Finally, we extend our methods to deal with languages with non-Boolean negation. Keywords: Expressive power, modal logic, negation-free languages.&lt;/p&gt;</style></abstract></record></records></xml>