A pairwise exchange is a neighborhood move that swaps two task positions in a candidate sequence. In assembly line balancing, the swap is accepted only when precedence constraints remain feasible. section 6.6
Use the move within tabu search as follows:
- Represent the solution as a task permutation. section 6.6
- Generate candidate neighbors by exchanging every pair of task positions. section 6.6
- Discard swaps that violate task precedence, then evaluate the remaining candidates. section 6.6
- Record the selected exchange in the tabu structure for the specified tenure. section 6.6
Six-task assembly line
With six tasks, exchanging two positions produces at most C(6,2) = 15 neighbors. From [1 2 3 4 5 6], precedence filtering leaves (1-2), (2-3), (3-4), and (5-6) as feasible swaps. Choosing (1-2) yields [2 1 3 4 5 6], and that exchange becomes tabu for three iterations. section 6.6
Figure 6.22 Precedence diagram example for six tasks
Use the precedence diagram to check whether each exchanged task order remains feasible. section 6.6
