This paper deals with two-processor scheduling for general acyclic SWITCH-less program nets with random node firing times. First, we introduce a hybrid priority list L* that has been shown to generate optimal schedules for the acyclic SWITCH-less program nets with unity node firing times, of which AND-nodes possess at most single input edge. Then considering the factors of existence of the AND-nodes with two input edges as well as random node firing times, we extend L* to design a new dynamic priority list Ld and four static priority lists {Lsii=1,2,3,4}; and then combining Ld and Lsi (i=1,2,3,4) we propose four hybrid priority lists {L*ii=1,2,3,4}. Finally, we apply genetic algorithm to evaluate the schedules generated by the four lists through simulations on 400 program nets. Our simulation results show two of the four lists can generate reasonably good schedules.

A data-flow program net is a graph representation of data-flow programs consisting of three types of nodes, AND-node, OR-node and SWITCH-node, which represent arithmetic/logical, data merge and context switch operations respectively. Minimum firing (completion) time T of a program net is an important element in computing parallel degree PARAdeg residing in a data-flow program and is defined as the minimum time when the program net is executed by enough many processors. In this paper, we propose algorithms to efficiently compute T by contracting AND-nodes generally for self-cleaning SWITCH-less program nets with arbitrary node firing time and give the experimental results of the algorithms to show the efficiency.

A data-flow program net is a graph representation of data-flow programs consisting of three types of nodes, AND-node, OR-node and SWITCH-node, which represent arithmetic/logical, data merge and context switch operations respectively. Token self-cleanness is an important property of a data-flow program and is such that if date-flow programs satisfy the property then a date-flow computer can efficiently withdraw copies from given programs during executions. In this paper, we classify program nets into SWITCH-less, OR-less and general nets, and analyse structures of data-flow program nets to propose verification methods of token self-cleanness by investigating token numbers appearing on the edges. As a result, a necessary and sufficient condition is proposed for SWITCH-less data-flow program nets and sufficient conditions are given for OR-less and general data-flow program nets.