Configuration: TOML Support for Local Search

[lv416e]

Current State

Local search operators in MAB scheduler must be hardcoded:

UCBLocalSearchSelector<TSP> selector(3, 2.0, rng);
selector.add_operator(LinKernighan(20, 5), "LK");
selector.add_operator(TwoOpt(), "2opt");

This means researchers must recompile to change operators or parameters.

Goal

Enable configuration via TOML:

[local_search]
scheduler = "UCB"
exploration_rate = 2.0

[[local_search.operators]]
type = "LinKernighan"
k_nearest = 20
max_depth = 5

[[local_search.operators]]
type = "TwoOpt"

This enables:

• Parameter tuning without recompilation
• Reproducible experiment configurations
• Template-based configs (e.g., configs/memetic_eax_lk.toml)

Solution

Implement runtime operator selection using std::variant:

using LocalSearchVariant = std::variant<LinKernighan, TwoOpt, Random2Opt>;

// Factory creates operators from config
LocalSearchVariant create_from_config(const std::string& type, const Config& params);

Why std::variant: Zero runtime overhead, type-safe, covers research use cases.

Tasks

• Add std::variant based operator factory
• Extend TOML schema for local search config
• Update AdaptiveLocalSearchSelector to accept variants
• Create example config templates (configs/memetic_*.toml)