Stockfish - UCI chess engine, compiled by Lolligerhans Rating JCER=3090 Timestamp: 1610872559 Add penalty for doubled pawns in agile structure Give an additional penalty of S(20, 10) for any doubled pawn if none of the opponent's pawns is facing any of our - pawns or - pawn attacks; that means, each of their pawns can push at least one square without being captured. This ignores their non-pawns pieces and attacks. One possible justification: Their pawns' ability to push freely provides options to react to our threats by changing their pawn structure. Our doubled pawns however will likely lead to an exploitable weakness, even if the pawn structure is not yet fixed. Note that the notion of "their pawns not being fixed" is symmetric for both players: If all of their pawns can push freely so can ours. All pawns being freely pushable might just be an early-game-indicator. However, it can trigger during endgame pawns races, where doubled pawns are especially hindering, t...