Swap mutation generates a neighboring permutation by selecting two genes at random and exchanging their positions. It introduces a small perturbation while preserving a valid permutation, mainly retaining adjacency information but disrupting some of the original order. section 8.3.2
Four-city tour
For the feasible tour {1,2,4,3}, swapping cities 3 and 4 produces {1,2,3,4}; swapping 2 and 3 produces {1,3,4,2}; swapping 2 and 4 produces {1,4,2,3}. These pairwise exchanges form neighboring solutions for tabu search. section 6.2
The operator appears in permutation-based genetic algorithms and as a building block for discrete particle swarm optimization, where a velocity is represented as a sequence of swaps that transforms one city permutation into another. section 8.3.2 section 9.4
Figure 8.10 Mutation methods in permutation-based GA
Compare swap mutation with insertion, inversion, and scramble mutation to select the perturbation that best balances retained structure and disruption. section 8.3.2
