Season 22 premier division, after RR2

 Standings after RR2

There is a clear divide between the top 3 and the bottom 5 in the table. The 3 leaders drew all their head to head matches and won 14/15 games against the bottom 5 as white. KomodoDragon is the only engine to win a game as black, a double win against ScorpioNN. Leela is in 3rd place since it lost as black against rofChade, after winning as white.

Within the bottom 5 ScorpioNN has 2 game pair wins and no loss, all other engines have at least one win and one loss against another bottom 5 engine. Stoofvlees is disappointing so far with 2 game pair losses and no game pair wins (two white wins against rofChade). 

The book openings have a high bias in favor of white, as a result the results after one RR depend on the opponents each engine faces as white. For example, Stockfish has only one game as white against a bottom 5 engine in the first RR, while Leela and KomodoDragon have 3.

Interesting games

game 1, ScorpioNN - rofChade: ScorpioNN exposed the black king, then gave a rook for a bishop and pushed a pawn to h6. rofChade gave the material back but the threat to its king was too great. ScorpioNN used its advantage to reduce to a rook ending 3 pawns up and win. It waited until it had 3 queens before mating.

game 2, KomodoDragon - SlowChess: After a few pawn and minor piece exchanges evals started to increase. The black pawn structure was weak, KomodoDragon captured a pawn and the remaining 4 pawns were isolated. KomodoDragon reduced to a queen ending, then used checks to capture another pawn and create an advanced passer. SlowChess couldn't prevent a queening and mate followed.

game 4, Leela - Igel: Leela captured a pawn in the opening, Igel did not castle its king. There was only one minor piece exchange in the first 30 moves, evals started to increase when more pieces were exchanged. The game reached a RB vs RB position on move 41, Leela still a pawn up with connected passers on the queen side. Leela pushed a passer to the 6th rank, then captured another pawn and created a passer on the king side. Igel could not stop 3 white passers, Leela gained material and won.

game 5, rofChade - Igel: rofChade went a pawn up and its eval jumped. The game reached a QRB vs QRN position, rofChade placed its bishop on d5 and when Igel exchanged it with its knight a white pawn became a passer. The engines reduced to a queen ending, eval were high but progress was slow as the queens danced on the board. rofChade needed more than 30 moves to promote a pawn, followed by mate.

game 7, SlowChess - Stoofvlees: Stoofvlees was confident it was holding, but somewhere around move 30 it made mistakes. After Stoofvlees moved without thinking SlowChess' eval jumped. Two moves later Stoofvlees spent 9 minutes thinking and its eval jumped as well. The game reached a QRB vs QRB position, SlowChess had an advanced passer on the 6th rank. After exchanging bishops SlowChess pushed the passer to the 7th rank and Stoofvlees had to block with its queen. SlowChess gave a pawn and exposed the black king, after exchanging rooks it was able to force Stoofvlees to move the black queen and promote its passer. Stoofvlees delayed using checks but couldn't avoid mate.

game 8, ScorpioNN - KomodoDragon: See featured game below.

game 9, KomodoDragon - rofChade: Evals started to increase after rofChade moved its queen forward, it found a safe spot on the queen side but KomodoDragon shifted its focus to the king side. KomodoDragon pushed pawns forward and moved its pieces to the king side, rofChade gave a knight for a pawn to avoid exposing its king. After exchanging queens the attack stopped, KomodoDragon slowly exchanged pieces until only RB vs R remained. The engines traded pawns and the game ended in a tablebase position with one last white pawn on the board.

game 11, Leela - SlowChess: The white queen came forward and captured a pawn. Leela gave a bishop but was 4 pawns up with connected passers on the queen side. After exchanging queens evals started to jump, SlowChess had trouble defending against the passers while keeping its pieces and pawns safe. Leela gained material and the game reached a RN vs BBN position with white 5 pawns up. Leela queened twice and mate followed.

game 14, SlowChess - Igel: The engines castled in opposite directions, Igel gave a pawn and all files on the queen side were semi-opened facing the white king. However, evals increased as SlowChess captured a second pawn and its king was never in danger. The game reached a RRB vs RRN position, SlowChess pushed two passers on the queen side. After exchanging a pair of rooks Igel lost the knight for a passer, the game ended in a tablebase win.

game 17, Stoofvlees - rofChade: The black queen captured a pawn on the queen side and Stoofvlees pushed pawns on the king side. rofChade gave a rook for a bishop to avoid having a strong passer on the 6th rank. rofChade captured the passer and the game reached a RB vs NN position. Stoofvlees gradually captured all the black pawns, the game ended in a tablebase win.

game 20, Stockfish - SlowChess: SlowChess pushed pawns on the queen side facing the white king. The engines played out a long PV agreement which led to a RBN vs RRB position. Stockish was two pawns up with a queen side passer, evals increased as Stockfish gradually improved its position. Stockfish created a passer in the center and reduced to a B vs R ending. SlowChess captured one passer but lost its rook for the other, game over.

game 21, rofChade - SlowChess: The engines castled in opposite directions, evals gradually increased even though rofChade gave a pawn. It slowly took control of the center before regaining the pawn. rofChade created a passer and reduced to a double rook ending. SlowChess captured the passer but rofChade doubled rooks on the 7th rank, then it went two pawns up and exchanged a pair of rooks. The game ended in a tablebase win.

game 23, KomodoDragon - Igel: The engines castled in opposite directions, evals gradually increased from the start. KomodoDragon ignored the black pawns moving forward on the queen side, it gave a pawn and opened the g file. The threat of a king side attack forced Igel to defend, KomodoDragon regained the pawn and exchanged pieces. The black pawns were all isolated, KomodoDragon captured 3 before exchanging queens leaving only RB vs RN. Igel couldn't stop the white passers and the game ended in a tablebase win. 

game 25, Leela - rofChade: The engines exchanged pieces and Leela went up a pawn. The game reached a QB vs QB position, the white queen was active and the black king was more exposed to attacks. It took some time but Leela managed to capture a second pawn before exchanging queens. The bishops were of the same color, Leela queened a pawn to win.

game 26, Igel - Stoofvlees: The game reached a RR vs BBN imbalance. Stoofvlees thought it was safe when it grabbed a pawn without thinking, it saw the danger immediately on the next move. Igel opened the center with a rook for bishop exchange, it started to attack the black king in a QR vs QBN position. The black king ran to the center, Igel gained material in the process and this led to mate.

Standings after RR1: KomodoDragon +4, Leela +3, Stockfish +1, ScorpioNN 0, Stoofvlees -1, rofChade SlowChess -2,  Igel -3. The openings are highly biased towards white, the results so far are affected by the number of white games each engines played. The top 3 engines beat the bottom 5 engines in 7/8 games when playing white, and drew all head to head games. Stockfish had only one game in white against the bottom 5, it may close the gap in the reverse games. KomodoDragon leads after 3 wins as white and an unexpected win as black. The games within the bottom 5 engines are more mixed. Only ScorpioNN is without loss against the bottom 5 with one win, the other engines have at least one win and one loss.

game 31, Stockfish - Stoofvlees: Stoofvlees gave a pawn and opened the center, Stockfish's eval jumped. Then Stoofvlees gave a second pawn and Stockfish reacted with another eval jump. Stoofvlees then offered a knight but never expected Stockfish to take. For a short while Stoofvlees thought it had some counter attack on the white king, but Stockfish soon showed there was no attack. After a few exchanges Stockfish attacked and mated.

game 36, KomodoDragon - ScorpioNN: KomodoDragon had an eval advantage from the start in a closed position. The first exchange was on move 25, the queen side opened a little and KomodoDragon went up a pawn. ScorpioNN regained the pawn a few moves later, however it was not careful with its king's safety and evals started to jump. KomodoDragon opened the position with a knight sacrifice and then attacked the black king. KomodoDragon used the attack to equalize material and reduce to a double rook ending. KomodoDragon had the initiative, it captured a pawn and exchanged a pair of rooks, leading to a tablebase win. A double win for KomodoDragon in this opening.

game 40, Stockfish - Igel: The game reached a QRB vs QRB position, evals were not increasing and it seemed Igel was holding on. Suddenly Stockfish's eval jumped as it exchanged bishops, it used a mate threat to capture a pawn. After exchanging queens Stockfish captured the black pawns until there were none left, the game ended in a tablebase win.

game 41, Stockfish - rofChade: Stockfish castled long though it had almost no pawn support on the queen side. When rofChade tried to attack evals started to increase, Stockfish used pieces to protect its king and opened a file on the king side. Stockfish maneuvered its knight to e6, then gave a pawn to open a second file and threaten the black king. rofChade preferred to trade RR for Q, but then it had to deal with passers on the queen side. Stockfish captured a rook for a passer, the game reached a QBN vs RBB position. The material advantage secured another queening, game over.

game 42, Igel - SlowChess: There were many early exchanges and for a long while the engines mainly shuffled. Evals started to increase gradually from around move 40, Igel slowly increased the pressure on the unprotected black pawns. After exchanging a pair of rooks Igel managed to capture a pawn on move 61, then reduced to a QN vs QN position with connected passers on the queen side and another passer on the king side. SlowChess tried to delay with checks but eventually Igel queened and won. There were two white wins in this opening.

game 43, Leela - ScorpioNN: The engines castled in opposite directions and slowly exchanged pieces. Evals increased when ScorpioNN tried to attack on the queen side and moved its queen forward. Leela opened the g file and threatened the black king. ScorpioNN lost a bishop and Leela reduced to a RN vs R position. Leela created an unstoppable passer and won.

game 45, rofChade - Stoofvlees: Stoofvlees moved without thinking and captured a free knight, it missed rofChade's response on move 22. Evals immediately jumped as rofChade created connected passers in the center on the 6th and 7th ranks. rofChade gave a rook and gained two knights for one passer. Stoofvlees tried to counter with an attack on the white king but was not strong enough. It blocked the other passer with a rook, but eventually rofChade managed to mate on the back rank. There were two white wins in this opening.

game 47, ScorpioNN - Igel: The game reached a RB vs RN position. ScorpioNN had a significant eval advantage, there was a black pawn on e4 that could have been taken but ScorpioNN kept waiting for the right moment. It finally took after 30 moves of shuffling, but after Igel exchanged rooks evals dropped. The game ended in a tablebase draw. Was it a missed win for ScorpioNN?

game 50, Stockfish - ScorpioNN: Evals gradually increased from the start. Stockfish focused on the black e6 pawn while ScorpioNN pushed pawns on the queen side facing the white king. Stockfish captured the black e pawn, and used open files to threaten the black king. ScorpioNN had to lose material and the game reached a QB vs RB position, mate was inevitable.

game 52, Leela - Stoofvlees: Stoofvlees blundered on move 25, this time after thinking for over a minute. Leela's eval jumped as it targeted the black pieces. Stoofvlees had to protect its pieces and Leela attacked the black king, mate came quickly. 

game 53, rofChade - Leela: rofChade went up a pawn early, evals increased very slowly for a long time. The engines gradually exchanged pieces, by move 56 only QR vs QR remained. The black king was vulnerable to attacks, eventually rofChade gave the pawn back temporarily but won it back while attacking. Leela only delayed the mate but couldn't avoid it. There were two white wins in this opening.

game 54, Stoofvlees - Igel: The game reached a QR vs QB position and evals started to increase. Igel was a pawn up with connected passers but the black king was exposed. Stoofvlees pinned the black bishop on the back rank, evals were high but Stoofvlees couldn't find a way to win. It gave a pawn and exchanged queens, the game ended in a tablebase draw. Surely a missed win for Stoofvlees.

game 56, ScorpioNN - SlowChess: ScorpioNN gave a pawn early, then pushed the black pieces back with its pawns. Evals jumped after ScorpioNN gave another pawn and traded N for R. The game reached a RRB vs RNB position, evals were high but progress was slow. It took more than 20 moves for ScorpioNN to capture a pawn and create a passer. After a second pawn became a passer ScorpioNN exchanged a pair of rooks. SlowChess captured one passer but lost its bishop, the game ended in a tablebase win. 

Featured game: ScorpioNN - KomodoDragon
Premier division, game 8
Link to game on TCEC

ScorpioNN had an eval advantage from the start, the center was blocked and there were very few exchanges. On move 32 the pawns stopped moving with the queen side blocked as well. The engines shuffled for a long time, ScorpioNN would not lower its eval below 1. It pushed the h pawn with 2 moves left on the 50-move counter, its eval dropped but it avoided an immediate draw.

KomodoDragon thought this was a mistake, evals became negative and quickly increased with both engines blitzing. Most of the white pieces were on the open king side, KomodoDragon gave a knight for a pawn on the queen side and created a passer on the 2nd rank. 

ScorpioNN tried to counter with an attack on the black king, it was not strong enough and there was not enough time to arrange the pieces. KomodoDragon removed the rook blocking its passer and eventually queened it. 

The material advantage was sufficient for a quick win. An unexpected win by black, ScorpioNN should have taken the 50-move draw.