6.5 hours? oh man
i was right, nmp only gained like 30 elo, gained much much more before. i tried to hunt down anything weird but i had to leave it at that. i also implemented pruning in quiescence search, so the engine only searches moves that have a positive static exchange evaluation (essentially, the result of all trades on a particular square).
i also accidentally found out my engine was doing fail-hard on beta cutoffs instead of fail-soft! in a fail-soft framework, the search is allowed to return outside of the bounds set by the alpha and beta parameters (it’s hard to explain succinctly here and i don’t want to keep doing it, search up alpha-beta search if you’re interested). thus, alpha and beta are soft bounds. this means each search returns more information about the move score.
i successfully did fail-soft on the alpha (lower bound) side, but not on the beta side due to what i can only assume is a coding mistake. the problem is, when switching to fail-soft on beta, the engine lost like 30 elo! i bisected the change to the LMR (late move reductions) patch, but still have no idea why LMR doesn’t play nice with fail-soft beta. i’m kinda at the end of my rope here, i might just have to eat the elo loss…