中文摘要：

混合作业是经典的自由作业和异序作业的一种综合，其中一些工件可以按任意的机器顺序进行处理，而另一些工件必须遵守预先指定的机器顺序．本文研究安装、加工和拆卸时间分离的两台机器混合作业排序问题，该问题已经被知道是强NP困难的，本文把流水作业中的同顺序作业概念推广到混合作业，并得到这个混合作业问题在同顺序意义下的最优解，这个解对于一般情形是3／2近似解，但对于一些有意义的特殊情形是整体最优的．

英文摘要：

A mixed shop is the combination of an open shop and a job shop, where some jobs can be processed in arbitrary machine orders, while the other jobs must follow fixed machine orders. In this paper, we consider the two-machine mixed shop scheduling problem with setup, processing and removal times separated. The problem has been known strongly NP-hard. We generalize the permutation schedule concept of the flow shop, and present a simple algorithm to find a best permutation schedule that is a 3/2- approximation and is globally optimal for some interesting special cases.