@techreport{R-90-45, PSURL = {/publications/cgi-bin/tr-fetch.pl?r-90-45+ps}, ABSTRACTURL = {/publications/cgi-bin/tr-fetch.pl?r-90-45+abstr}, ABSTRACT = {We propose a new method for characterizing the discontinuities in processes that are mostly continuous. We introduce a causal operator that is used to specify when the value of a fluent has a cause. A discontinuity in a fluent is allowed if the fluent's value immediately after the discontinuity has a cause. The causal operator is incorporated in a temporal logic with continuous time and real-valued fluents. The resulting logic is a nonmonotonic logic suitable for representing physical models of real world situations. We define a selection function which given a set of models returns a subset of the models. This selection function defines a nonmonotonic entailment operator. The intuitive idea behind the selection function is that is should select all models where all discontinuities are ``specified'' as allowed. }, TITLE = {Cause as an Operator in a Logic with Real-valued Fluents and Continuous Time}, AUTHOR = {Tommy Persson and Lennart Staflin}, EMAIL = {tompe@ida.liu.se}, YEAR = {1990}, NUMBER = {R-90-45}, INSTITUTION = ida, ADDRESS = idaaddr, IDANR = {LiTH-IDA-R-90-45}