Standings after RR2
As in the previous season, the top 3 engines are a lot better than the rest of the field. In the first DRR the top3 won 12/15 game pairs against the rest, without loss. Stockfish, Leela and KomodoDragon has each "dropped" one game pair with a draw result. Stockfish is in the lead since it also beat both Leela and KomodoDragon in their game pairs.
Within the botttom5 engines Ethereal and Stoofvlees are a little better with 2 game pair wins. rofChade lost 3 game pairs, it would have been last if not for drawing twice against the top3. This seems somewhat lucky, there is a good chance it will drop down in the coming rounds.
Interesting games
game 1, rofChade - SlowChess: The game started with a 23-ply book in the Sicilian opening, accelerated Dragon variation, with the engines castled in opposite directions. SlowChess pushed pawns and attacked on the queen side, rofChade controlled the center and pushed a pawn to h6. Evals gradually increased as the engines reduced to a double rook ending. rofChade captured a pawn and created a passer on the queen side. The black king walked to the center, rofChade used the time to open the king side and push a rook forward. SlowChess avoided mate and captured the passer on the queen side, but lost a rook for a passer on the king side, game over.
game 3, Stockfish - Berserk: The game started with a sideline of the Sicilian Dragon, Yugoslav attack. Again the engines castled in opposite directions, Berserk pushed pawns on the queen side. The game quickly reached a QRR vs QRR position and Stockfish pushed a pawn to h6. For a long while it seemed the engines were shuffling but evals slowly increased, on move 44 Stockfish gave a pawn and opened the king side. The black king was threatened, Berserk couldn't hold all its pawns and Stockfish went a pawn up, then reduced to a double rook ending. The white king was safer and Stockfish had connected passers on the queen side, it pushed the passers and captured two more pawns. Berserk couldn't avoid a queening and mate.
game 4, Leela - KomodoDragon: The game started with another variant of the Sicilian Dragon, Yugoslav attack. The engines castled in opposite directions as before, this time Leela captured an early pawn and there were no black pawns on the queen side by move 20. The queens were exchanged, KomodoDragon regained the pawn and slowly pushed pawns in the center while Leela pushed pawns on the queen side with the white king supporting from behind. A black bishop was trapped on the king side and KomodoDragon gave its central pawns to release the bishop. The combination of passers advancing and threats on the black king gave Leela the win.
game 11, Leela - Stoofvlees: Evals did not change a lot in the first 35 moves, the engines exchanged pieces and pawns and opened the queen side. Leela thought move 35 by Stoofvlees was a mistake, Stoofvlees had the game continuation in its PV and thought it was ok. In a QRN vs QRN position Leela moved its rook forward. Stoofvlees tried to counter with a back rank attack but it realized it was in trouble. The white king found safety and Leela started to chase the black king while capturing pawns. Both engines queened a pawn but Stoofvlees couldn't escape and was mated.
game 12, KomodoDragon - Berserk: The game started with a 32-ply book in the Ruy Lopez, Flohr system, with all pieces on the board and one pair of pawns exchanged. There were no exchanges after book and the engines seemed to be mostly shuffling, though evals increased slowly. After move 38 there were a few exchanges, Berserk gave a rook for a knight and tried to push pawns on the queen side. KomodoDragon pushed the h pawn, the engines reduced to a RRN vs RNN position with a pawn on the 7th and 2nd rank. KomodoDragon was a pawn up with a passer in the center, the black king was trapped in the corner. Berserk was forced to lose material, KomodoDragon queened and mated.
game 13, SlowChess - Berserk: Both engines castled long, there was a period of shuffling and then evals started to increase. SlowChess had a bishop pair while Berserk had two knights. The king side opened and SlowChess created a passer in the center, then it captured a pawn and added a second passer on the king side. Berserk captured one passer but lost a rook for the other. After exchanging queens only RBB vs NN remained, the game ended in mate.
game 17, Stockfish - SlowChess: SlowChess was outplayed in the opening though it was a pawn up, evals increased rapidly. The black king could not castle and stayed in the center, SlowChess tried to attack on the queen side but was not effective. Stockfish regained the pawn, then gave a rook for a knight to open the center. Stockfish used the threat to the black king to gain material, mate came quickly.
game 19, KomodoDragon - rofChade: The center was blocked, KomodoDragon had a space advantage and there were only a few black pieces near the black king. rofChade captured a pawn but evals kept increasing, KomodoDragon regained the pawn and opened the king side. The black king was forced to run and KomodoDragon pushed a passer forward. rofChade lost a rook for the passer, it took KomodoDragon another 30 moves to mate.
game 20, Berserk - Stoofvlees: Stoofvlees castled long, Berserk did not castle but moved its king forward. Berserk opened the a file, on move 24 Stoofvlees blundered ignoring its king safety. Berserk doubled rook and queen on the a file and then sacrificed its bishop. Stoofvlees realized too late that its king was in trouble, it tried to move pieces to defend but there were no pawns left on the queen side. Berserk reduced to a Q vs RR position, it pushed a passer to the 7th rank then traded Q for R and added a second passer. Stoofvlees couldn't stop a queening and mate.
game 24, Stockfish - Leela: See featured game below.
game 25, Leela - SlowChess: The engines castled in opposite directions, Leela pushed pawns on the king side and doubled rook and queen on the half open f file. Evals increased as Leela placed its knights in the center, SlowChess defended by exchanging pieces, after a long PV agreement only QRR vs QRR remained. Leela captured a pawn and exchanged queens, then slowly pushed a passer on the queen side. After exchanging a pair of rooks Leela captured another pawn, SlowChess had no defense and the game ended in a tablebase win.
game 28, Stoofvlees - rofChade: The engines castled in opposite directions, Stoofvlees gave 2 pawns on the king side and exposed the black king to attack. Stoofvlees doubled pawns on the f file, rofChade gave a rook for a bishop and a series of exchanges reduced to a RBN vs BNN position. After exchanging a pair of knights the engines traded pawns until both were down to their last pawn. The 8-man endgame was very long, the bishops were of opposite color and the black bishop was mostly static defending the pawn. Stoofvlees kept attacking the black knight and king, after 40 moves it managed to trap the black king on the h file. Stoofvlees used the threat of mate to reduce to a tablebase win.
Standings after RR1: Stockfish +3, Leela +2, KomodoDragon +1, Ethereal 0, rofChade Stoofvlees -1, SlowChess Berserk -2. The 3 engines at the top were expected, Stockfish is without loss, it beat Leela and Leela beat KomodoDragon in their first games. Ethereal drew all its games in RR1.
game 29, SlowChess - rofChade: The engines castled in opposite directions, SlowChess pushed pawns on the king side and gave one. rofChade gave a rook for a knight on the queen side and immediately regretted it as both evals jumped over 4. SlowChess gave its queen and attacked the black king, there followed a series of exchanges that left only RRB vs Q on move 28. The white king was protected, SlowChess captured all the black pawns and then slowly pushed the black king back, game over. There were two white wins in this game pair.
game 32, KomodoDragon - Leela: The game repeated the reverse game 4 with a transposition for 27 plys, the engines castled in opposite directions and there were no black pawns on the queen side. Leela saw it was in trouble, it chose not to wait for the advancing pawns on the queen side and it sacrificed two minor pieces for two passers. Leela then attacked the white king and got some of the material back, the game reached a RB vs R position with black two pawns up. KomodoDragon captured one pawn quickly, all remaining pawns were on the king side. Both engines were sure of a white win but it wasn't clear how KomodoDragon could penetrate the black fortress. It took 40 moves for KomodoDragon to capture a pawn, then it queened a pawn and mated quickly. There were two white wins in this game pair.
game 33, KomodoDragon - SlowChess: There was a diagonal pawn wall in the center, the engines made openings on both sides. KomodoDragon had two advanced knights on the queen side, SlowChess traded a bishop for one and captured a pawn. This allowed KomodoDragon to push a passer to the 7th rank on the queen side. Evals increased rapidly, KomodoDragon moved its pieces forward and the queens were exchanged. KomodoDragon captured two pawns and had a bishop pair advantage, SlowChess lost a rook for the passer and mate followed.
game 34, Leela - Berserk: Leela gave a knight for a pawn, then created an advanced passer on the queen side. Berserk moved its queen forward facing the white king, it thought it was still ok. A few moves later Berserk understood Leela's plan and its eval jumped. With the passer on the 7th rank Leela sacrificed a rook, then pinned and captured the black queen for another rook, and finally trapped a black rook using its king as an attacking piece. The game reached a QB vs RBN position, the white passer was gone and Berserk tried to build a fortress with its pieces. It took Leela another 20 moves to create another passer, then it reduced to a tablebase win.
game 35, Stockfish - Stoofvlees: There was a pawn wall across the whole board except a half open h file, with all pieces on the board. Stockfish had a space advantage, it was unclear how it could penetrate the wall yet evals slowly increased. After a long period of apparent shuffling Stockfish exchanged minors and gave a pawn to open the g file. It took 20 moves to double rooks on the g file with the black king in the corner. Stockfish ended the game with knight and rook sacrifices followed by mate.
game 36, Ethereal - rofChade: The engines opened the c file and Ethereal placed a secure bishop on b6. After a few minor piece exchanges the white king walked to the queen side with evals increasing. rofChade gave a knight for two pawns, creating two passers in the center. Ethereal exchanged pieces and captured the passers, the game reached a RBN vs RN position. It took Ethereal more than 30 moves to capture the remaining black pawns and reduce to a tablebase win.
game 41, Berserk - SlowChess: Berserk grabbed an early pawn with its queen, the white king stayed in the center without castling and the game reached a RRB vs RRN position. SlowChess gave a pawn, this gave Berserk a passer and a weaker pawn structure. Evals started to increase, SlowChess managed to equalize material but Berserk created a second passer and pushed it forward. SlowChess lost a rook for a passer, Berserk won more material and the game ended in a tablebase win. There were two white wins in this game pair.
game 42, KomodoDragon - Stoofvlees: KomodoDragon was a pawn up with a bishop pair but its king was stuck in the center with open files on both sides. On move 16 Stoofvlees blundered and gave a knight, it thought it had a strong attack on the white king as compensation. A few moves later Stoofvlees thought long and its eval jumped as well. Stoofvlees got some material back but the white king stayed safe surrounded by pieces. KomodoDragon attacked the black king with its queen, eventually it captured a rook to win.
game 43, Leela - rofChade: Both engines castled long, after exchanging queens evals started to increase slowly. Leela had a bishop pair advantage, the engines reduced to a RBB vs RNN position. rofChade gave a pawn to create a passer, while blocking a white passer on the queen side. While rofChade pushed its passer Leela pushed a pawn on the king side that also became a passer. rofChade couldn't stop this pawn and was forced to lose a rook, leading to mate 15 moves later.
game 44, Stockfish - Ethereal: Evals started to increase after move 20. Stockfish went a pawn up and reduced to a QRN vs QRN position. Most pawns were on the board, the engines mostly shuffled for a while and then Stockfish captured another pawn and exchanged queens. The game reached a rook ending, Ethereal couldn't stop all the advancing white pawns and the game ended in a tablebase win.
game 47, rofChade - KomodoDragon: KomodoDragon chose a line that started with a queen exchange and capturing a pawn, and ended in a RB vs R position on move 25. KomodoDragon was 3 pawns up with 3 passers on the queen side, it tried to protect them and push them safely forward. However, after 20 moves rofChade captured a pawn on the king side and the white rook moved behind the passers. KomodoDragon lost all its pawns and rofChade reduced to a tablebase win. There were two white wins in this game pair.
game 48, Stoofvlees - Berserk: Berserk castled long, Stoofvlees moved its king forward instead of castling, similar to the reverse game 20. Berserk captured a pawn and left two half open files on the queen side with rooks facing the black king. Stoofvlees increased the pressure on the queen side, Berserk started a series of exchanges in PV agreement that resulted in a RRB vs RBN position. Berserk was 3 pawns up and Stoofvlees had a passer on the 7th rank. Berserk captured the passer and exchanged a pair of rooks, but Stoofvlees slowly captured black pawns until it was 2 pawns up. The game ended in a tablebase win. There were two white wins in this game pair.
game 49, Stoofvlees - SlowChess: There were only a few exchanges after the start, the engines mostly played behind their pawn lines. Evals slowly increased after the queens were exchanged. After move 45 SlowChess started to push pawns on the queen side, not sure if that was necessary or it just lost its patience. The queen side opened and the game reached a RRB vs RRN position. Stoofvlees had connected passers in the center, SlowChess gave a knight for a pawn perhaps out of desperation but it couldn't avoid a queening, game over.
game 50, Berserk - rofChade: The game started with a 20-ply book in the Queen's Indian, Petrosian variation, with rofChade a pawn up. The line was played by Karpov in the 1990s. Exchanges opened the center and rofChade castled long. Berserk had active bishops and evals slowly increased. Berserk gave a bishop for two pawns and this left the black king surrounded by pieces without pawn support. Berserk avoided exchanging queens, it used threats on the black king to capture a rook for a bishop. The game reached a RRB vs RBN position, it took Berserk 25 moves to capture all the black pawns and trap the black knight, the game ended in a tablebase win.
game 51, KomodoDragon - Ethereal: The game started in the Queen's Indian, Fianchetto Nimzowitsch variation, played by Kasparov in the 1990s. KomodoDragon went a pawn up early, there were a few minor piece exchanges in the center. KomodoDragon had a passer in the center but it did not advance, the engines tried to avoid contact and mostly shuffled for a long time. On move 56 there was pawn movement on the king side and KomodoDragon captured a second pawn. Evals started to increase, Ethereal gave a rook for a bishop and tried to attack the white king. In a QRR vs QRB position the exposed white king moved forward to find a safe square, the KomodoDragon reduced to a winning R vs B ending.
game 54, Stockfish - KomodoDragon: Both engines kept their kings in the center without castling, there were many early exchanges and evals increased steadily. Stockfish went a pawn up, the engines reduced to a BN vs BN position on move 31. Stockfish captured the rest of the black pawns by move 48 and the game ended in a tablebase win.
game 55, Ethereal - Berserk: The engines castled in opposite directions, evals increased right from the start. Ethereal pushed pawns on the king side, Berserk kept its king protected and instead Ethereal created a passer in the center. After queens were exchanged Berserk gave a knight for two pawns to capture the passer. The game reached a RRN vs RR position and the endgame as very long. The engines traded pawns and eventually only one white pawn was left. Ethereal was able to keep the last pawn safe, the white king found a square where it wouldn't be in check. Ethereal exchanged a pair of rooks and the game ended in a tablebase win on move 92.
Featured game: Stockfish - Leela
game 24
The game stared with a 20-ply book in the Queen's Indian, Fianchetto variation. The engines played out a 24-ply PV agreement from the start, evals did not change a lot. On move 23 Leela went a pawn up at the cost of allowing Stockfish to create an advanced passer in the center. Stockfish saw this as a blunder immediately, Leela thought it was perfectly safe.
Stockfish's move 26 surprised Leela, Stockfish gave a bishop but pushed its passer. Leela thought for over 5 minutes and its eval jumped. The passer could not be stopped and Leela lost a rook for it. The exchanges continued and the game reached a RB vs BN position.
The endgame was very long and slow. Leela tried to keep its pawns for as long as it could, and capture a white pawn when it lost one. By move 58 the engines were down to one pawn each. Leela's eval was only a little over 1 at this point, compared to nearly 15 for Stockfish.
Stockfish prevented the advance of the black pawn, it took 20 moves to get its pawn to the 5th rank. Leela chose to support its pawn with the king, this allowed Stockfish to trap the black king, queen its pawn and mate.
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