JISE


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Journal of Information Science and Engineering, Vol. 25 No. 6, pp. 1963-1978


Deadlock Control for Weighted Systems of Simple Sequential Processes with Resources Requirement (WS3PR)


DANIEL YUH CHAO+
Department of Management and Information Science 
National Cheng Chi University 
Taipei, 116 Taiwan 
E-mail: yaw@mis.nccu.edu.tw


    Current deadlock control approaches for WS3PR (Weighted Systems of Simple Sequential Processes with Resources Requirement) suffer from incorrect liveness characterization based on the concept of deadly marked siphons (DMS). We discover that nonlive transitions may exist even though there are no DMS. That is, the net model may be weakly live or in livelock states under no DMS. It is live under a new liveness condition: all siphons must be max*-controlled. We extend the liveness analysis for S3PR (systems of simple sequential processes with resources) to WS3PR(Weighted Systems of Simple Sequential Processes with Resources Requirement). We develop a new liveness condition called max*-controlled siphons to replace that of the absence of empty siphons. We propose further a deadlock control policy for WS3PR by adding control nodes and arcs similar to that for S3PR.


Keywords: Petri nets, siphons, traps, FMS, liveness, deadlock, control

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