Minimizing total completion time for flowshop scheduling problem with uncertain processing times

The four-machine flowshop scheduling problem is investigated with the objective of minimizing total completion time. Job processing times are uncertain where only lower and upper bounds known. This common in some manufacturing environments. Some mathematical (dominance) relations established, an algorithm (with ten scenarios) proposed. proposed converts to a single machine for which optimal solution known deterministic problem. difference among scenarios related weights assigned on machines. further improved by established evaluated based extensive computational experiments. results indicate that three perform much better than others, errors these get as size increases. statistically verified constructing confidence intervals.