AB-JChess vs Pikafish: two wins, read by both engines

Two of AB-JChess's wins from the 2026-09-29 match against Pikafish, every position scored again by both engines, Pikafish's moves marked by AB-JChess and its own choices as sidelines. From the post on AB-JChess at mistboard.com/blog/ab-jchess.

2 chapters

1. Game 68: AB-JChess vs Pikafish, read by both engines53 moves

   Game 68 of the 2026-09-29 match, 400 games at 4 seconds a move: AB-JChess red, Pikafish black. Both engines scored every position again: AB-JChess at 1 million nodes, the fixed Pikafish at 64 million; scores are expected results, a draw counting half. Marks are Pikafish's moves a…

   Black's chariot takes a face-down advisor on a1. AB-JChess has Red at 65%; Pikafish, searching this position itself, has Red at 44%. AB-JChess preferred face-down piece h8-f8, but by its count the game move cost under 5 points. Searched longer, AB-JChess keeps its choice (Black 3…

2. Game 6: AB-JChess vs Pikafish, read by both engines95 moves

   Game 6 of the 2026-09-29 match, 400 games at 4 seconds a move: AB-JChess red, Pikafish black. Both engines scored every position again: AB-JChess at 1 million nodes, the fixed Pikafish at 64 million; scores are expected results, a draw counting half. Marks are Pikafish's moves as…

   ?! By AB-JChess's count this drops Pikafish from 51% to 45%; it preferred cannon h8-e8, the line beside this move. Searched longer, AB-JChess rates them the same (Black 49%); Pikafish prefers the game move (Black 55% against 50%).