Season 19 premier division, after RR4

Standings after RR4

Stockfish and Leela lead the table, AllieStein is 2 points behind. It is still early, each engine has 28 more games to play, yet the current leaders will probably play in this season's superfinal.

There are 4 engines in danger of being relegated. Fire dropped to the bottom after it lost 3 games in this DRR. Komodo was a point behind after RR3 but pulled itself up and is still in the race.

Almost all the decisive games are between the top4 and the bottom4 engines. Stockfish is the only engine to beat another top4 engine (twice, AllieStein and Stoofvlees). There are two games in which a bottom4 engine beat Stoofvlees, in both cases the reverse was won by Stoofvlees.

So far the change in openings has not affected the draw rate which continues to be around 80%. There were fewer decisive games in the second DRR than in the first. This is not a complaint, I am fine with this draw rate.

Interesting games

Game 58, Leela - Fire: Leela had a better position with eval over 1, Fire had a defense line across the board that Leela could not penetrate. The engines started to shuffle on move 42, Leela avoided a 50-move draw by giving a rook for a bishop and creating a passer. The shuffling continued for 30 more moves and evals slowly came down, then Leela had enough support to push the passer forward and evals started to increase. Leela captured 2 pawns and exchanged queens, Fire was busy blocking the passer and Leela was able to capture a rook for a knight and reduce to a winning RN vs RN ending 2 pawns up. Did Fire blunder?

Game 60, Stoofvlees - Komodo: Komodo had a weak knight that was almost trapped on the queen side. Stoofvlees' eval was over 1.5, the engines shuffled and exchanged pieces slowly. On move 62 the black knight was fully trapped and protected by a bishop. Komodo gave a rook for a knight to save its knight, but the resulting RN vs BN ending was a win for Stoofvlees.

Game 65, Leela - ScorpioNN: ScorpioNN grabbed two pawns with a knight, while leaving its king alone and in danger. Leela increased the pressure on the king side, ScorpioNN gave the knight for a pawn and exchanged pieces. The game reached a RB vs R position, black 2 pawns up with connected passers. Leela exchanged rooks, the bishop blocked the black passers and Leela queened a pawn to win.

Game 66, AllieStein - Stockfish: AllieStein traded Q for RNN early, it thought it had an advantage but Stockfish was sure in its defense. The engines mostly shuffled until AllieStein's eval came down for the draw rule.

Game 68, Komodo - Ethereal: Komodo may have had a chance in a RB vs RB position, but once it allowed a rook exchange the game reached a drawn bishop ending. 

Game 71, Stockfish - Stoofvlees: See featured game below.

Game 73, AllieStein - ScorpioNN: AllieStein possibly missed a win around moves 35-40, ScorpioNN had its major pieces on the queen side and AllieStein could have opened the king side to attack the black king. Instead ScorpioNN sacrificed a rook to open the queen side and exposed the white king. AllieStein thought it was winning but it missed black's 43rd move which forced it to give back a knight. AllieStein's attack on the king side came too late and wasn't strong enough. The engines exchanged pieces and gave checks, the game ended in a tablebase draw.

Game 78, Stockfish - Ethereal: The king side was quiet and the kings were safe while the action was on the queen side. Stockfish's eval started to jump as the engines exchanged major pieces along open files, the game reached a BN vs BN position. Both engines had a passer on the queen side, Stockfish blocked the black pawn while pushing its own to the 7th rank. After forcing a bishop exchange Stockfish used two pawns and its knight to prevent the black king from approaching the passer, the white king was free to pick pawns on the other side for the win.

Game 79, Leela - Komodo: The engines shuffled from move 21, a few pawn moves extended the game past move 120 with low evals. It appeared that Komodo blundered, it captured a rook for a knight but its queen was trapped in the corner. Leela reduced to a rook ending and went two pawns up, enough for a win.

Scores after RR3: Stockfish +6, Leela +5, Stoofvlees AllieStein +1, Fire -2, Ethereal ScorpioNN -3, Komodo -5. Stockfish and Leela extend their lead, AllieStein and Stoofvlees are unable to keep up. Four engines fighting against relegation, Komodo is sinking.

Game 88, Komodo - Stoofvlees: Stoofvlees gave a pawn and attacked the king side. Komodo captured a second pawn and exposed the black king, Stoofvlees continued to make threats on the king side but Komodo was confident its king was safe. Komodo's eval jumped when its queen came forward and captured two more pawns using checks. Stoofvlees' attack became irrelevant when Komodo pushed a passer to the 7th rank, the game ended in mate on the board. Two white wins in this opening.

Game 90, Stoofvlees - Ethereal: A 13 move miniature, a 3-fold almost immediately after book.

Game 91, AllieStein - Fire: AllieStein's eval increased after the start, the game reached a RBB vs RBN position and its eval was over 2. AllieStein gave two pawns and created a king side passer. The black king was too far away to help, Fire had to block with its rook. The white bishop pair was very strong, AllieStein created a second passer in the center and pushed it forward to win.

Game 92, Leela - Stockfish: The game reached a RRB vs RBB position with black 2 pawns up. Leela'a eval was close to 1 but it couldn't break through the black pawn wall. After a lot of shuffling and a rook exchange the position opened and the game ended in a tablebase draw.

Game 107, Komodo - Leela: Leela traded Q for RBB, then used the exposed white king to force a draw.

Game 111, Leela - Ethereal: Ethereal traded a rook for a bishop and pawn early. Evals remained be around 1 for many moves, the engines exchanged pieces and the game reached a RBN vs BBN position. On move 62 the engines exchanged a pair of bishops and evals started to increase. Leela was down to one pawn, but with patient and accurate play it managed to convert the win.

Game 112, Stockfish - Fire: Stockfish started the game with an eval of 1, it pushed pawns on the queen side and got as far as a5 and b6. After a few exchanges Stockfish captured a pawn and created a pawn majority on the queen side, its eval was over 6 by then. There were a few shuffling moves and then Stockfish used a queen exchange to get a pawn to the 7th rank. Fire had to give a rook to stop the passer and the game was over.

Featured game: Stockfish - Stoofvlees
Premier division, game 71
Link to game on TCEC

Stockfish's eval steadily increased after the opening, it jumped over 3 after a file on the king side was opened. Most of the black pieces were far on the queen side and the black king was not safe. Stoofvlees chose to fight back, it traded RN for Q to stop Stockfish's threats and started a king side attack on the white king.

Stoofvlees continued to give material to open the king side and keep the attack going at all cost, it sacrificed a knight to remove a pawn and then gave a rook to remove one of the defending bishops. Stockfish kept calm even though it seemed its king was totally exposed with very few pieces defending it.

However, the white king always had a way to escape, Stoofvlees could not ignore the material difference and its eval increased as well. The game was adjudicated with Stockfish a full queen up and about to capture another piece.