Standings after RR4
Stockfish and Leela continue to lead the division, extending their lead slightly. There are 28 more rounds to play so anything can still happen, but it seems probable that they will play in the superfinal. Stockfish won 6/7 game pairs in the second DRR, including wins against Leela and KomodoDragon. Leela also won 6 game pairs, but lost one to Stockfish. It is interesing to note that so far Stockfish has won 12/14 games in white, while Leela won 13/14.
Interesting games
Game 62, Stockfish - KomodoDragon: Evals gradually increased though material was equal. KomodoDragon had two isolated pawns on the queen side which had to be defended, and Stockfish had a bishop pair advantage. On moves 54 and 58 the engines traded a pair of pawns and both created passers on the queen side. KomodoDragon tried to open the king side, this only exposed its king to attack. Stockfish quickly shifted to the king side and captured a knight. KomodoDragon couldn't deal with the advancing passer and the threat to its king, both engines saw the mate coming.
Game 66, Ethereal - Stoofvlees: A series of early exchanges reduced to a rook ending. Both engines created a passer on the queen side, Stoofvlees blocked its own passer with the rook while Ethereal had an open path forward for its passer, supported by the king. The game ended a few moves after Ethereal queened its passer.
Game 71, Stoofvlees - KomodoDragon: After the start the engines mostly played behind their pawn lines with only a few exchanges, evals increased slowly. On move 40 Stoofvlees created a passer by a pawn trade. KomodoDragon opened a hole in the pawn wall on the king side, then blocked it with a bishop that couldn't move. After a period of mostly shuffling Stoofvlees moved its king toward the center and evals jumped. KomodoDragon gave a pawn and opened a file on the queen side, then traded its bad bishop for a knight. Only major pieces remained, Stoofvlees finally pushed its passer on move 96. It captured a second pawn and reduced to a rook ending two pawns up, enough for a win.
Game 76, Stockfish - Leela: see featured game below.
Game 81, KomodoDragon - AllieStein: The center and queen side were blocked except for the open a file, KomodoDragon with a space advantage. AllieStein gave a pawn to get more space on the king side. KomodoDragon took over the a file with a rook exchange and moved its remaining rook forward. The game reached a QRB vs QRN position, KomodoDragon gave back a pawn to open a file on the king side and threatened the black king on light squares. The white queen moved forward, KomodoDragon gave its rook for the knight and captured 4 pawns. AllieStein couldn't stop the white passers, lost its rook and the game.
Game 84, Leela - Stoofvlees: Leela captured a pawn and created a queen side passer, Stoofvlees blocked it with a rook. The engines exchanged pieces and evals increased, in a QRB vs QRN position Leela abandoned the passer but took over the back rank. It chased the black king all the way to h3, Stoofvlees gave material but only delayed the mate.
Scores after RR3: Stockfish +8, Leela +6, KomodoDragon +3, Stoofvlees AllieStein +1, ScorpioNN Ethereal -5, rofChade -9.
Game 85, AllieStein - Stoofvlees: A long PV agreement starting from move 14 led to a QB vs RRN imbalance. Both engines moved pieces forward and captured most of the pawns on the queen side. AllieStein's eval increased to around 2 and then Stoofvlees blundered and evals jumped. The black king was in danger, and the two black rooks on the 2nd rank were too far to help and too late to counterattack. AllieStein exposed the black king and mate followed.
Game 95, Leela - KomodoDragon: Evals were under 1 until move 36. Material was equal and Leela's advantage was not obvious, perhaps a better pawn structure, or better piece arrangement. Evals continued to increase, KomodoDragon traded a bishop for a white knight in the center and the engines reduced to a BB vs BN position. The bishop pair was strong and Leela went two pawns up, it had enough pawns left to win.
Game 97, Stockfish - AllieStein: Evals stayed around 1 for a long time. The engines opened a file on the queen side and AllieStein kept a rook there. After a period of mostly shuffling Stockfish gave a rook for a bishop and pawn and the position opened up. Then there was a series of exchanges that followed a long PV agreement, reducing to a RBB vs RR position with black two pawns up. Stockfish's eval jumped after AllieStein pushed its pawns too far in Stockfish's opinion. AllieStein allowed a bishop for rook trade, perhaps thinking that the RB vs R ending would be a draw with only one white pawn left. It soon realized its mistake as Stockfish patiently moved its king forward and threatened mate. AllieStein could only delay it for a few moves by giving the rook.
Game 99, KomodoDragon - Stoofvlees: The engines exchanged minor pieces and evals increased slowly. The black king was partially exposed and KomodoDragon moved pieces to the king side. Stoofvlees gave a rook for a knight and pawn, maybe it hoped its bishop pair would help in defending the king. Komodo continued to attack, with one rook on the 7th rank and its queen on the king side the black king was soon in a mating net. A double white win in this opening.
Game 105, Leela - AllieStein: AllieStein gave a knight for pawns and created connected passers on the queen side. In a RBB vs RB position Leela attacked the passers with a bishop and AllieStein moved its rook to defend in front of the pawns. Leela thought this was a mistake, it quickly trapped the rook. The black bishop tried to help and got trapped as well. Leela used its pawns and extra bishop to create a passer and AllieStein could not stop it. The passer queened and mate followed.
Game 106, Stockfish - Stoofvlees: Stoofvlees captured a pawn and Stockfish's eval jumped, it immediately reacted with a knight fork and captured a rook for the knight. Stoofvlees was confident it had enough compensation as it attacked the exposed white king. Only 15 moves later Stoofvlees realized Stockfish had a way out. The attack ended in a queen ending, Stoofvlees captured two pawns but Stockfish's last pawn was an unstoppable passer. Stockfish quickly mated in a QQ vs Q position.
Game 110, Ethereal - rofChade: Ethereal's eval jumped after the queen side opened. rofChade had a passer on the queen side but also an isolated pawn in the center. After exchanging queens Ethereal took over the center and moved a rook to the 7th rank. rofChade exchanged a pair of rooks and reduced to a RB vs RN position. Ethereal captured a pawn, then blocked the passer and continued to capture black pawns until there were none left. The game ended in a tablebase win a few moves later.
Featured game: Stockfish - Leela
Premier division, game 76
Link to game on TCEC
Stockfish castled long and Leela kept its king in the center. Leela moved its queen forward on the queen side and started to push pawns facing the white king. Stockfish
offered a knight for two pawns, Leela chose to leave the knight and
attack the white king. Stockfish captured a rook, Leela's queen and bishop pair looked scary but Stockfish was confident it can survive the attack.
Leela chased the white king to the center and Stockfish had to give back material. Stockfish exchanged pieces and the attack was over in a RB vs RB position, white a pawn up with a passer on the 7th rank.
Stockfish
avoided an opposite color bishop ending, it gave up the b7 passer and moved its king forward to support the pawns on the king side. The engines traded pawns until
only 2 vs 1 remained.
Stockfish pushed 2 passers forward supported by its king, while its rook controlled the 7th rank. Leela started to lose its pieces and the game ended.
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