Stockfish and Leela will play in the season 15 superfinal, a rematch of the previous superfinal. Ethereal and Fire are relegated to division 1.
The final RR did not change the engine ranking, and the top and bottom of the table were already obvious. There was one interesting result, Leela beat Stockfish in their final game of the division. This may indicate that this season Leela will be the superfinal champion.
The four engines in the middle were close during the whole division. Komodo finished ahead of the rest by a small margin, all four engines had similar strength. Of the 36 games these 4 engines played each other only 4 were decisive, including a crash by KomodoMCTS. AllieStein started this season as a newcomer NN engine in division 4, getting to the premier division and staying there is a great achievment. KomodoMCTS solved most of its stabillity issues of last season, if it continues to improve it may become better than its older relative Komodo.
The superfinal will start in about two weeks, I will be on a break until then. TCEC continues with the cup event that will start tomorrow.
A few interesting games
Houdini - Fire: Houdini had a space advantage, it pushed its king side pawns forward, leaving its king with no support and threatening the black king. Fire switched its king and rook back after castling, so the king would have an escape route. Houdini's eval increased as it played on both sides, pushing the black pieces back. Fire gave a pawn but couldn't stop Houdini's attack. Houdini won more material and the game was adjudicated with mate in the PV.
AllieStein - Houdini: AllieStein's eval increased quickly as it opened the king side and exposed the black king. Houdini hid its king behind a white pawn and the game reached a QRB vs QRB position on move 32. The engines exchanged queens and AllieStein went two pawns ahead. AllieStein's eval peaked over 6, the engines just shuffled and AllieStein couldn't find the win. The game continued to move 153 and ended in a tablebase draw.
Stockfish - KomodoMCTS: Stockfish's eval increased quickly from the start as it pushed pawns on the king side. The black pieces were stranded on the queen side, Stockfish gave a knight to open the king side on move 25 with both evals over 6. The black king had to run and KomodoMCTS lost its queen, the game was adjudicated in a QB vs RN position.
Komodo - Fire: On move 30 most pieces were on the board, Fire had a passer on the e file and Komodo had a pawn majority and a potential passer on the c-d files. Evals increased gradually as the engines exchanged pieces, on move 44 only QRB vs QRN remained. White's passer on d6 was more advanced and more supported, the black king was exposed to attack. Fire tried to counterattack, Komodo was careful not to allow a perpetual check and the game was adjudicated in a winning QB vs Q position. Two wins for Komodo in this opening.
Leela - AllieStein: Evals were over 1 from the start, there were many early exchanges and only RRN vs RRN remained on move 17. Leela gave a rook for a knight and two pawns and created a queen side passer. Leela pushed the passer to the 7th rank with eval over 2, AllieStein countered with checks and it seemed it was holding. Then on move 60 evals jumped as AllieStein miscalculated and stopped the checks at the wrong moment. Leela lost the queen side passer but reduced to a N vs R ending with 3 connected passers in the center. AllieStein realized it was losing, and as we have seen before in this division it just gave away the rook and lost immediately.
Stockfish - Fire: Stockfish's eval climbed after the start, reaching over 1.5 with all the pieces on the board. The center was blocked and Stockfish controlled an open file on the king side. The first pieces were exchanged on move 36, Stockfish created an advanced passer on the king side and its eval jumped over 2.5. Evals increased quickly, Stockfish exchanged BN for R and Fire created a passer on the queen side. Stockfish trapped a knight and then captured it, the game was adjudicated with Fire losing more material.
Leela - Stockfish: see featured game below. Leela wins the 6th and last head-to-head game against Stockfish.
Featured game: Leela - Stockfish
Premier division, game 161
Link to game on TCEC
Leela had an eval over 1 from the start, the engines only exchanged a pair of knights, both played behind their pawn lines. The center was blocked early, and Leela's eval jumped over 2 after the blocking the king side as well.
Stockfish's pawns on the queen side limited the movement of the black pieces. Leela shifted its pieces to the queen side and its eval increased quickly, Stockfish's also increased but more slowly. On move 35 the engines exchanged pawns for the first time, Leela was confident it was winning.
The queen side opened up and Leela's major pieces controlled the open files. Stockfish tried to challenge the white king safety but Leela closed the gap with a bishop. Evals kept jumping higher, though material was equal. Only on move 51 Leela went up a pawn, creating a potential passer on the queen side.
Leela concentrated on exchanging pieces, the game reached a RBN vs RBN position on move 60. The black central pawns became defenseless and Leela exchanged knights and went 3 pawns up.
This was an easy endgame, the game was adjudicated 15 moves later.