Season 21 premier division, final results

Final standings

Stockfish and Leela will play in the season 21 superfinal. In the last DRR Stockfish won 6/7 game pairs while Leela managed only 5. Leela beat Stockfish in a game pair once in the division, the only game pair loss for Stockfish, while Leela did not lose a single game pair. The reason Stockfish won the division is that it beat KomodoDragon 3 times, while Leela only managed 4 drawn game pairs.

Igel and Ethereal are relegated to league 1. Ethereal was clearly headed for relegation. Igel may have dreamed of surviving, but after it lost to ScorpioNN for the 3rd time it couldn't recover. Both Igel and Ethereal played in league 1 this season, and both were not strong enough to stay in the premier division.

AllieStein had a miserable score of -5 in the last DRR, including losses to Stoofvlees, Igel and Ethereal. For 3 DRRs it tried to keep up with 4th place Stoofvlees, in the end it was closer to 6th place ScorpioNN.

In the last DRR the top4 engines beat the bottom4 engines in 15/16 game pairs without loss, an incredible achievment, better that all the 3 DRRs before.

Interesting games 

game 169, Stockfish - AllieStein: AllieStein pushed pawns on the king side and its king was left with little pawn support. Stockfish created a central passer, there were many exchanges and Stockfish's eval increased despite giving a rook for a bishop. The game reached a RN vs RR position, Stockfish pushed its passer to the 7th rank and AllieStein's eval finally reacted. Stockfish pushed 3 passers on the king side, AllieStein saw it was lost. It gave a rook and was mated quickly.

game 170, KomodoDragon - Igel: Evals started over 1 and they increased while the engines cleared most of the queen side pawns and concentrated on the king side. The black king was threatened, KomodoDragon gave a rook for a knight and opened the king side with its queen. Igel quickly exchanged queens after KomodoDragon captured two pawns.The black king was still in danger, Igel was forced to give a rook for a knight to avoid mate. The game reached a RN vs RN position, KomodoDragon was 3 pawns up. It took 20 more moves to reach a tablebase win.

game 171, Leela - Ethereal: The center was blocked and most pawns were on the board, evals increased slowly. Ethereal was forced to move a rook and couldn't castle, Leela gave a pawn and knight for the rook. Leela then opened a file on the queen side and doubled its queen and rook there. After exchanging rooks only QRN vs QBN remained, in a series of exchanges Ethereal reduced to a QN vs Q position with connected black passers. Ethereal didn't have time to turn its passers into real threats. Leela captured a pawn and created a passer, then captured one of the black passers. Ethereal couldn't prevent a white queening, game over.

game 172, Stoofvlees - ScorpioNN: ScorpioNN moved a rook forward and grabbed a pawn on the queen side. Stoofvlees reacted on the king side and drove the black king to the center. ScorpioNN made a mistake in a complicated position with all the major pieces in the center of the board. The result was a series of exchanges that left only QB vs Q. ScorpioNN offered its queen and was mated.

game 176, Stockfish - KomodoDragon: The center was blocked and the queen side was open, evals around 1. On move 20 the engines started a long shuffle, Stockfish thought KomodoDragon's move 54 was a mistake and its eval jumped over 2. Stockfish created a passer in the center, and after exchanging queens went up a pawn and created a passer on the queen side. KomodoDragon captured the queen side passer and another pawn, by then Stockfish had a rook on the back rank. Stockfish captured a bishop and reduced to a RBN vs RN position. The black king was in a mating net, game over.

game 179, Stoofvlees - Igel: Evals were below 1 for a while, Stoofvlees' eval jumped with all the black pieces on the queen side. Stoofvlees gave a knight for a pawn and created an advanced central passer. Igel gave a bishop to capture the passer and Stoofvlees reduced to a RB vs RB position a pawn up with connected passers on the queen side. Igel couldn't stop both passers and had to lose a piece, the game reached a tablebase win.

game 180, ScorpioNN - Ethereal: Evals started around 1 and slowly increased, all the pieces were on the board and the engines opened files on the queen side. Evals were over 4 when ScorpioNN captured a rook for a knight on move 41. For a long while the engines exchanged pieces and shuffled and evals went down a little. On move 80 the game reached a RB vs BB position and evals climbed again. On move 90 there was only one white pawn left in a 7-man position. ScorpioNN did not blunder and managed to convert the win.

game 183, Stockfish - Stoofvlees: Stoofvlees seemed to be holding until move 35 with most pieces on the board, despite being two pawns down. Stoofvlees captured a pawn and exposed its king to attack, Stockfish's eval jumped over 2.  Stockfish gave a rook for two minors and attacked the black king, Stoofvlees reduced to a QBN vs QR position. Stoofvlees played almost automatically for 11 moves, its eval close to 0 while Stockfish already saw mate. Stoofvlees stopped to think and its eval jumped over 8, too late.

game 185, Leela - AllieStein: The engines castled in opposite directions, Leela's eval jumped after it took over the open h file with a rook. After it doubled rooks on the open file AllieStein gave its queen to capture one of the rooks. AllieStein had connected passers on the king side but they were not strong enough. Leela started to chase the black king and mate came quickly.

game 190, Stockfish - Ethereal: The engines castled in opposite directions, evals were around 1 without much change after the start. After a few minor piece exchanges evals slowly increased, the black DS bishiop was trapped on the king side. The engines gradually exchanged pieces until only BN vs BN remained, Ethereal was out of moves and Stockfish started to capture pawns. The game reached an opposite color bishop ending, Stockfish had enough pawns to win.

game 191, KomodoDragon - ScorpioNN: KomodoDragon's eval jumped over 2 on move 36, it gave a pawn and opened the king side. ScorpioNN only realized what was happening 3 moves later, when KomodoDragon broke through the center and offered a rook that couldn't be accepted. KomodoDragon moved the rook to the back rank, all the white pieces were involved in the attack and the black king was stuck in the center. KomodoDragon used the attack to capture pawns on the queen side, it created an unstoppable passer and promoted to a queen. ScorpioNN gave up and got mated quickly.

game 192, Leela - Stoofvlees: Stoofvlees ignored the danger to its king and tried to capture a rook for a knight. Leela's eval jumped over 6 as it ignored the knight and attacked the black king. Stoofvlees saw the danger 4 moves too late, it was a rook up but its king was in the center of the board. Leela chased the king, gaining material until it mated.

game 193, Stoofvlees - AllieStein: There were no exchanges until move 23, evals were around 1 and the engines opened the king side a little. Evals increased slowly at first, AllieStein played defensively while Stoofvlees arranged its pieces on the king side. Evals started to jump and Stoofvlees gave a rook for a knight and captured two king side black pawns. The engines reduced to a QN vs QR position, with a white passer in the center and the black king exposed. AllieStein had no escape, it lost material and was mated.

Scores after RR7:  Stockfish +17, Leela +15, KomodoDragon +9, Stoofvlees 0, AllieStein -5, ScorpioNN -7, Igel -11, Ethereal -18. At this stage the standings seem to be stable. Leela has a small chance of finishing first. AllieStein dropped away from Stoofvlees and is closer to ScorpioNN at this point.

game 202, Stoofvlees - Ethereal: The engines started a series of exchanges on move 19, resulting in a RRB vs RRN position. Stoofvlees went a pawn up before Ethereal exchanged a pair of rooks. Ethereal regained the pawn but Stoofvlees pushed a passer to the 7th rank and Ethereal gave the knight to stop it. The game continued for 20 moves and ended in a tablebase win.

game 203, Leela - Igel: Leela offered a knight on the king side, but Igel refused to take and expose its king. Leela increased the pressure on the king side and evals increased. Leela captured a rook for a bishop, then Igel finally accepted the knight and a R vs BN imbalance. Leela captured a knight and reduced to a RN vs BN position, after exchanging knights Leela had enough pawns to win

game 209, Ethereal - AllieStein: The white queen moved forward early, AllieStein gave a rook for a knight. The engines gradually exchanged pieces while evals increased, the white queen found a safe way back. Ethereal gave the material back in a series of exchanges that reduced to a QR vs QR position. The black king was exposed to attack, Ethereal chased it and captured pawns in the process. It was 3 pawns up when AllieStein gave up its pieces and was mated. First game pair win for Ethereal.

game 210, ScorpioNN - Igel: Evals were around 1 from the start, there were almost no exchanges and one open file in the center. Igel moved its queen forward and exchanged queens, ScorpioNN went a pawn up and evals slowly increased. The pieces were exchanged until the game reached a knight ending on move 58. ScorpioNN needed 20 more moves to convert the win.

game 214, KomodoDragon - Stoofvlees: See featured game below.

game 215, Stockfish - ScorpioNN: Evals were around 1 and the engines castled in opposite directions. ScorpioNN concentrated forces on the queen side, it tried to push pawns and open files. Stockfish exchanged minor pieces and created a central passer while evals increased. The white king hid behind a black pawn and Stockfish pushed the passer to the 7th rank. The white king remained safe, eventually ScorpioNN lost a bishop for the passer, it gave up its queen and got mated.

game 216, Igel - Ethereal: The engines castled in opposite directions, Igel pushed pawns on the king side and exposed the black king. Evals were over 2 on move 18, they increased for a while but then started to drift down. It seemed Ethereal stopped Igel's attack and Igel had to change its plan. On move 50 evals started to increase again, both engines were down to two pawns. After exchanging queens Igel pushed a passer to the 7th rank in a RBN vs RBN position. Ethereal started to lose material and the game ended in a tablebase win.

game 217, Igel - AllieStein: The engines castled in opposite directions, evals were over 1 and slowly increased as the engines exchanged minor pieces. Evals were over 3 when the king side started to open, a series of exchanges reduced to a QR vs QR position. Igel had a passer on the 7th rank and the black king was exposed, AllieStein couldn't hold and got mated.

game 222, Leela - ScorpioNN: Evals stayed under 1 as the engines slowly exchanged pieces. The game reached a QRB vs QRN position on move 52, then the rooks were exchanged. On move 77 the pawns stopped moving and the engines shuffled for 30 moves. Evals started increasing very slowly, ScorpioNN probably made small mistakes and Leela took over. Leela pushed a pawn to the 7th rank, and gave the bishop to promote to a queen. Mate came after ScorpioNN ran out of checks.

game 223, KomodoDragon - Ethereal: Evals started around 1 and increased a little, there were very few exchanges and the engines played behind their pawn lines. The first piece exchange was on move 30, then KomodoDragon pushed a pawn on the king side and evals started to increase. After some shuffling KomodoDragon captured a pawn on the queen side and created a passer, Ethereal was careful not to open the king side. KomodoDragon opened the g file on move 47 with winning evals, Ethereal countered by pushing a central passer to promotion. The engines reduced to a QNN vs QR position, after exchanging queens KomodoDragon had enough pawns to force a win.

game 224, Stockfish - Igel: The engines mostly shuffled from move 18, evals were under 1 until move 40. Igel saw an opportunity to grab two pawns, Stockfish's eval jumped over 3. It sacrificed a knight and opened the king side, attacking the black king. A series of exchanges reduced to a RR vs RB position. Stockfish captured pawns and gave a rook for a bishop to reach a wining rook ending two pawns up.

Featured game: KomodoDragon - Stoofvlees
Premier division, game 214
Link to game on TCEC

Evals started around 1 and didn't change for a while. KomodoDragon pushed pawns on the king side and castled long. The center was blocked and the king side partially open. Stoofvlees tried to weaken the white center pawns, KomodoDragon's eval jumped over 2 when it broke through the center with its queen and captured two pawns.

Stoofvlees thought it had a significant counter attack on the white king and its eval stayed low. It realized it was in trouble only 10 moves later, spending very little time thinking on these moves. KomodoDragon was up a piece and the black king was under pressure.

The white king was exposed but Stoofvlees did not have time to attack. It managed to get a little material back and exchange a few pieces. KomodoDragon was two pawns up with a queen side passer and the black king was not out of danger.

The black king faced a queen and two knights without pawn support. Stoofvlees moved its rook forward and attacked the white king. In desperation the black queen moved away from the king and threatened mate, this was all KomodoDragon needed to get the black king in a mating net and win.