Usually, most of the typical job shop scheduling approaches deal with the p
rocessing sequence of parts in a fixed routing condition. In this paper, we
suggest a genetic algorithm (GA) to solve the job-sequencing problem for a
production shop that is characterized by flexible routing and flexible mac
hines. This means that all parts, of all part types, can be processed throu
gh alternative routings. Also, there can be several machines for each machi
ne type. To solve these general scheduling problems, a genetic algorithm ap
proach is proposed and the concepts of virtual and real operations are intr
oduced. Chromosome coding and genetic operators of GAs are defined during t
he problem solving. A minimum weighted tardiness objective function is used
to define code fitness, which is used for selecting species and producing
a new generation of codes. Finally, several experimental results are given.