means that every position has been double-checked against a modern engine (Stockfish 16+), and every move sequence has been manually reconciled with the original 1994 English edition. This ensures that when you import the PGN into ChessBase, Lichess, or Chessable, the board matches the lesson exactly.
Avoid copy-paste PGNs from random forums. If the file does not explicitly say "Verified" or pass a Stockfish consistency check, it will teach you errors. A single wrong evaluation in a Polgar puzzle can ruin your intuition for a specific pattern. laszlo polgar chess middlegames pgn verified
means each position has been checked against a modern chess engine (Stockfish 16+ or Dragon) for: means that every position has been double-checked against
[FEN "r4rk1/ppp2ppp/2n5/3p4/1b1P4/2PB4/PP3PPP/R1B1K2R w KQ - 0 1"] laszlo polgar chess middlegames pgn verified