Hi community!
Sorry for spamming you with new versions, but my engine actively developing and today I have new release: VeryChess 0.4.0.
Release notes here: https://verychess.org/releases.html#v0-4-0
Download: https://verychess.org/download/verychess0.4.0.zip
General strength improvement history:
0.2.0 -> 0.3.0 (~46 ELO) -> 0.4.0 (~118 ELO)
Overview
This release covers two areas: a sharper quiescence search and a rebuilt static evaluation.
First, the quiescence search — the tactical search that runs at the leaves of the main search to resolve pending captures before the position is evaluated — was responsible for roughly 87% of all nodes searched, much of it spent on hopeless captures (a queen taking a defended pawn, a rook grabbing a piece and being lost immediately).
Second, the hand-crafted evaluation was rebuilt from a flat, hard-switched function into a tapered, component-based one — smoothly interpolated between middlegame and endgame by game phase — and gained full-board mobility, rook file evaluation, and drawn-endgame scaling.
Strength
The whole evaluation rework was validated as an SPRT-gated series at 30s + 1s (search depth matters little for evaluation, so a fast control is appropriate), each stage against the one before it. Measured end-to-end against the pre-rework build, the cumulative result is +117.9 ± 31.2 Elo. As always this is self-play at a fast control and overestimates the gain against other engines and at longer controls; the individual accepted stages were tapered eval +80, full mobility +92, rook files +34, and endgame scaling +18.
What's new
- Delta pruning in quiescence
- Static exchange evaluation (SEE)
- Tapered, component-based evaluation
- Full mobility.
- Rooks on open files.
- Endgame scaling.