Optimization, Tabu Search, Travelling Salesman.
can’t drop x3. From the remaining the best choice is to add x7 and drop x6. Then make x7 as tabu. The chosen move produce worst cost than the previous. Now we have x3, x7 are considered as Tabu. and if we want to make any move we will make the cost worse. so we are in a state that has a bad cost