@INCOLLECTION { Rsds2913,
author = {Peters, James F.}, 
title = {Time and Clock Information Systems: Concepts and Roughly Fuzzy Petri Net Models}, 
booktitle = {Rough Sets in Knowledge Discovery 2. Applications, Case Studies and Software Systems}, 
series =  = {Studies in Fuzziness and Soft Computing}, 
pages = {385--417}, 
publisher = {Physica-Verlag}, 
address = {Heidelberg, Germany}, 
year = 1998, 
editor = {Polkowski, Lech and Skowron, Andrzej}, 
isbn = {3-7908-1120-3}, 
abstract = {Based on observations concerning time its measurement, approximate time windows are introduced relative to vaguely known partitions of temporal intervals. Time window measurements are defined relative to durations between firings of transitions in Petri nets. The vagueness of the partitions of a time window stems from a lack of crisp knowledge of deadliness imposed on the activities (tasks) performed by agents. To model the construction of information system tables leading to approximate knowledge of observations extracted from time windows, a new class of fuzzy Petri nets is introduced, namely, roughly fuzzy Petri nets. In the context of approximate time windows for monitoring the time consumed by agents performing time-constrained tasks, roughly fuzzy Petri net models of clock representation system are given. Several sample information system tables and approximations with rough sets are also given. A sample decision system is also constructed relative to fuzzy aggregations of observed durations. Our approach is based on the rough sets method of constructing decision systems and recent work on modeling clocks with fuzzy sets.}, 
keywords = {approximate, clock, discernibility, fuzzy sets, information system, Petri nets, rough sets, time, }, 
}