Robust solutions to Job Shop problems

The problem of finding robust solutions for scheduling problems is of utmost importance for realworld applications as they operate in dynamic environments. In such environments it is often necessary to reschedule the existing plan due to various failures (e.g., machine breakdowns, sickness of employees, etc). Thus a robust solution (i.e., a quality solution which can be modified easily according to a change in the environment) may be more valuable than an optimal solution which does not allow easy modifications. In this paper the issue of robust solutions for job shop scheduling problems is considered. A robustness measure is defined and its properties are investigated. This study is supported by a series of experiments; the results indicate that robust solutions exist and can be identified.