Add a perturbation step to the VNS engine #305

bustikiller · 2025-07-24T11:45:07Z

bustikiller commented

2025-07-24 11:45:07 +00:00

The previous version of the VNS algorithm was focused on the local optimizations (swap and shift) but did not implement any perturbation.

In this PR, we are introducing a perturbation of variable size (1 to 3 guests randomly swapped to other tables) to visit other neighborhoods where the local optimum may be better than the best solution so far. Some values are hard-coded, and the engine probably needs some refactor to use a list of perturbations instead of knowing about Table::WheelSwap. Nevertheless, the benchmark rake task already shows significant benefits in using the perturbation local optimization VS not using it.

The previous version of the VNS algorithm was focused on the local optimizations (swap and shift) but did not implement any perturbation. In this PR, we are introducing a perturbation of variable size (1 to 3 guests randomly swapped to other tables) to visit other neighborhoods where the local optimum may be better than the best solution so far. Some values are hard-coded, and the engine probably needs some refactor to use a list of perturbations instead of knowing about `Table::WheelSwap`. Nevertheless, the benchmark rake task already shows significant benefits in using the perturbation local optimization VS not using it.

bustikiller added 9 commits 2025-07-24 11:45:07 +00:00

Rename perturbation -> optimization to reflect the nature of swap and shift operations e1a5e4f73e

Initialize empty set of perturbations and add debug messages 543b53d938

Include additional debugging messages 185f359942

Initialize Tables::WheelSwap class e8a88b50e2

Define a WheelSwap class that randomly swaps one guest from each table a1f06dae5b

Shuffle guests in WheelSwap before assigning them to new tables b1df5d2f53

Run perturbation on top of the best solution so far 4befb8505b

Introduce a wheel swap perturbation as part of the VNS engine process db85580c1f

Remove commented-out code

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