Tuesday, June 9, 2020

Season 18 premier division, after RR4

Crosstable after RR4

Stockfish leads the table, Leela is a point behind while Stoofvlees and AllieStein are still in the race. Stockfish had an outstanding RR3 with a +5 score, including wins against Stoofvlees and AllieStein. This was enough for the lead though it drew all the games in RR4. Leela continues to accumulate wins at a slower pace. Stoofvlees led after RR2 but had only one win since then to compensate for its loss and it dropped to 3rd.

At the bottom Fire and rofChade are on their way back to league 1, it is mostly a question which will finish last. Ethereal and Komodo are stable in the middle of the table, Ethereal is still without a win in the division.

There were 10 decisive games in RR3, of which 5 were Stockfish wins. There were a few more games with winning chances, at least one missed win by AllieStein. RR4 was less interesting with only 3 decisive games, all Fire losses.

Interesting games
Game 57, Leela - rofChade: rofChade was a pawn up with a queen side passer on the 2nd rank that Leela blocked with a rook. Leela exposed the black king and regained the pawn, evals stayed low and the engines shuffled for a while. Leela thought rofChade's move 50 was a blunder, within a few moves Leela captured the black passer and the black defense collapsed. The engines exchanged pieces and reduced to a RBN vs RBN position, Leela was 3 pawns up when the game was adjudicated.
Game 58, Stockfish - Fire: Stockfish had an eval advantage close to 1 after the start, Fire seemed to be holding as the engines slowly exchanged pieces. On move 35 the game reached a QRN vs QRB position and Stockfish's eval jumped over 2. The queens were exchanged and the engines started to capture pawns, Stockfish's eval climbing fast. On move 55 Stockfish went a pawn up, there were only a few pawns left and Stockfish seemed to have an unstoppable passer. Fire gave its last pawn in desperation and the game was adjudicated.
Game 59, AllieStein - Ethereal: AllieStein had a promising QRB vs QRB position with a passer on the 7th rank. Ethereal found a way to exchange pieces and get rid of the passer, the game reached a B vs pawns ending. Ethereal was 2 pawns up, all its pawns out of the bishop's reach. AllieStein wouldn't lower its eval, the game ended in a 50-move draw.
Game 61, rofChade - Stoofvlees: Stoofvlees sacrificed a bishop for pawns, but its attack on the white king wasn't strong enough. The engines reduced to a NN vs R position and the game ended in a tablebase draw.
Game 63, Fire - AllieStein: AllieStein missed a win in this game. Fire was two pawns up in a B vs BN position, with advanced connected passers on the 6th and 7th ranks. AllieStein probably made a wrong choice on move 47, its knight had to protect a pawn and its king blocked the passers, while the black bishop's targets were protected by the white king. The engines shuffled, AllieStein prolonged the game with pawn moves until adjudication on move 171.
Game 65, Stockfish - rofChade: Stockfish had an eval advantage from the start. It pushed the king side pawns forward and didn't castle its king. rofChade moved its queen forward on the queen side and captured a pawn, Stockfish immediately attacked while the black queen was away. It gave a rook for a knight, opened the king side with its pawns and took advantage of the fact that the black queen side pieces were undeveloped. Stockfish used the king side attack to regain the material, and created connected passers. Together with a mate threat this was enough for a win. 
Game 67, Komodo - Fire: Fire was up a pawn early but Komodo pushed a pawn to h6 and trapped a black bishop in the corner. The engines exchanged pieces gradually until only RBB vs RBB were left on move 34. Komodo was effectively a bishop up, the game was adjudicated after a few moves. This is Komodo's first win in the division. 
Game 72, Stockfish - AllieStein: See featured game below. First decisive game in the top 4, first loss for AllieStein.
Game 73, AllieStein - rofChade: AllieStein had a strong central pawn and a space advantage. The pawn became a passer, and eventually rofChade gave a knight to get rid of it. The game reached a RBN vs RN position on move 54, evals were high but AllieStein played 30 more moves of slow progress before the game was adjudicated.
Game 74, Komodo - Stockfish: Stockfish had an eval advantage under 1 (negative) from the start, Komodo had two isolated pawns on the queen side. The engines mainly shuffled and evals stayed constant until move 40. A few piece exchanges later Komodo managed to connect its pawns while Stockfish had a bishop pair and a queen side passer. Stockfish's eval jumped to around 3 on move 60, it used its passer to reduce to a R vs BB ending. The bishop pair was stronger than the rook, the game was adjudicated before Stockfish started to capture pawns.
Game 78, Leela - Ethereal: All the pieces were on the board until move 29, evals increased slowly. Leela had two strong knights in the center, Ethereal gave a rook to take one out. The engines exchanged pieces until only RR vs RBN remained, white two pawns up. Ethereal created a passer but it wasn't strong enough, Leela moved the rooks to the back rank and managed to capture the black knight. A few moves later Leela went a pawn up and the game was adjudicated. 
Game 79, Stockfish - Stoofvlees: Stoofvlees castled long, Stockfish's eval jumped over 1 after it opened the queen side. The white queen and knight chased the black king to the center, then Stockfish's eval jumped again when Stoofvlees gave a rook for a knight. The black king moved forward as Stockfish closed in. Stoofvlees had a 21 minute long think on move 30, the first time it realized it was in trouble. However, Stoofvlees' eval didn't increase fast enough, the white rooks got involved and the game ended with mate on the board. First loss for Stoofvlees in the division.
Game 81, Komodo - rofChade: Komodo had an eval advantage from the start, it pushed the black pieces back and evals increased to around 2. rofChade gave a rook for a knight and pawn, the game reached a RB vs BN ending that was a win for white, though the game continued for 20 more moves.

Scores after RR3: Stockfish +7, Leela +4, Stoofvlees +3, AllieStein +2, Komodo -1, Ethereal -2, Fire -5,  rofChade -8. Stockfish takes the lead after a fantastic RR with 5 wins, including wins against Stoofvlees and AllieStein. Leela took advantage of the losses of its opponents to move up to 2nd place, after a solid +2 in the RR. Komodo had a positve score after it beat Fire and rofChade, it moves away from the relegation line. Fire and rofChade continue to lose games, probably both will relegate. The reverse games are next.
Game 91, AllieStein - Fire: AllieStein tried to sacrifice a bishop for pawns and to expose the black king, Fire refused to take back and accepted the pawn loss. AllieStein's eval jumped over 2, and it continued to increase quickly as the engines exchanged pieces. The game reached a knight ending, Fire continued to play another 30 moves before its eval was high enough for the win rule.
Game 98, Stoofvlees - Fire: Stoofvlees pushed pawns on the king side and its eval increased over 1. Fire tried to use open files on both sides but had no real threats. Stoofvlees placed a protected knight on f6, its eval increasing steadily. By move 39 Stoofvlees was a pawn up in a BNN vs BNN position, 10 moves later it was two pawns up in a BN vs NN ending. The game was adjudicated after Stoofvlees went 4 pawns up.
Game 112, Leela - Fire: The engines castled in opposite directions, evals started to increase when Leela pushed pawns on the king side facing the black king. Fire hid its king behind a white pawn and tried to counter on the queen side, but its attack was too weak. Fire gave a rook for a bishop and the game reached a RR vs RB ending. Leela was not in a hurry, the black bishop did not have pawn targets. There were several 2-fold repetitions, eventually Leela found the winning path by capturing pawns and pushing a passer.

Featured game: Stockfish - AllieStein
Premier division, game 72
Link to game on TCEC

Stockfish started with an eval advantage under 1, evals stayed relatively low after the opening. The f file was half open early, nevertheless AllieStein decided to castle short. Stockfish doubled its rooks on the f file and on move 22 it sacrificed both its rooks for BN and exposed the black king. Evals increased to around 1.

Stockfish attacked on the king side, AllieStein exchanged pieces and gave some of the material back to save its king. The game reached a QB vs QR position with white 3 pawns up, evals did not change a lot and it was still possible that AllieStein could hold. 

Stockfish's eval fluctuated wildly for a few moves, the black king was in the corner with the rook pinned. After a few moves with low evals Stockfish found an advantage again, AllieStein captured 2 pawns and chased the white king around while Stockfish's eval increased over 4. When the checks ran out AllieStein was in zugzwang, 

AllieStein started pushing pawns and Stockfish captured them. AllieStein finally realized it was losing when it was down to its last pawn. Stockfish pushed a passer to the 7th rank and the game was adjudicated. 

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