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fix: --n-sim training parameter

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This commit is contained in:
Henri Bourcereau 2026-03-11 22:17:03 +01:00
parent ad30d09311
commit cf50784a23
2 changed files with 18 additions and 5 deletions
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15
spiel_bot/src/mcts/search.rs
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@ -156,7 +156,13 @@ pub(super) fn simulate<E: GameEnv>(
let returns = env
.returns(&next_state)
.expect("terminal node must have returns");
returns[player_idx]
let v = returns[player_idx];
// Update child stats so PUCT and mcts_policy count terminal visits.
// Store from player_idx's perspective so child.q() is directly usable
// by the parent's PUCT selection (high = good for the selecting player).
child.n += 1;
child.w += v;
v
} else {
let child_player = next_cp.index().unwrap();
let v = if crossed_chance {
@ -166,6 +172,13 @@ pub(super) fn simulate<E: GameEnv>(
// previously cached children would be for a different outcome.
let obs = env.observation(&next_state, child_player);
let (_, value) = evaluator.evaluate(&obs);
// Store from player_idx's (parent's) perspective so PUCT works correctly.
// `value` is from child_player's POV; negate when child is the opponent
// so that child.q() = expected return for the player CHOOSING this child.
// Without the negation, root would maximise the opponent's Q-value and
// systematically pick the worst action.
child.n += 1;
child.w += if child_player == player_idx { value } else { -value };
value
} else if child.expanded {
simulate(child, next_state, env, evaluator, config, rng, child_player)