Final standings,stage 1b:
Qualifiers are: Stockfish, Nirvana, Jonny, Fire, Naum, Chiron, Andscacs and Vajolet2. Like in stage 1a the final qualifiers were determined in the last round, Critter missing out on the very last match. Stockfish won the stage but it was a very close race. Crashes made an impact on qualification: without the extra points Naum and Andscacs would have had 9.5, same as Vajolet2 and Critter.
The final draw rate for stage 1b is 33/120 (27.5%). Almost identical to stage 1a.
Some of the game highlights:
Jonny was very confident it had a big advantage playing black against Naum with evals getting high very early in the game. Jonny had a pawn advantage in the RN vs RB endgame with a 4 against 2 pawns situation on the king side. It took a while but this was enough for a win. Will Jonny win the stage? It still has to face Nirvana.
Fire and Vajolet2 had a long struggle on the queen side, where Fire had a 3-2 pawn advantage, later reduced to 2-1. Fire came out ahead with two passed pawns and a big eval advantage. Vajolet2 was forced to lose material, reaching a BN vs B ending, 3-4 pawns on the king side. The game was adjudicated before there was any material change, but with black's pawns being targets for white's bishop. A huge result for the qualification of both engines, but nothing is determined yet.
Gaviota held the pawn line against Andscacs for almost 60 moves, but the position deteriorated quickly after Andscacs exchanged a rook for a knight and created a hole in the line.
Stockfish had a strong king side attack that forced Critter to lose a knight, leading to a winning RN vs R endgame. Stockfish winning the stage is almost certain.
Jonny had an eval advantage over Critter for 40 moves, with a significant advantage in space. When the position opened up a little it was suddenly Critter who was up on eval, but with only RB vs RN left a draw was more probable. The game ended with mutual queenings and a perpetual check.
Andscacs was hoping to be the first engine to beat Stockfish this Season. It held an eval advantage right from the opening for over 30 moves. Despite opposite castling the game remained relatively calm with no serious threats on either side. Eventually the evals dropped back to zero and a draw was reached. Jonny may still tie for first place, and Andscacs is still not qualified for sure, last game against Critter may be the decider.
Vajolet2 beat the Baron without too much trouble. It is still 9th but is not out of the race yet.
Chiron had a significant eval advantage over Fire, but as the game progressed with less and less material on the board it turned out that Chiron was two pawns up in an opposite bishop ending. The position became static, black not moving and white unable to move a pawn without losing it. And then for no reason Chiron crashed!! So sad... The last round is going to be tense.
Naum - Nirvana was one of those long and boring draws, this time in a BB vs BN ending. Naum waited 70 moves to lower its eval long enough for adjudication.
Jellyfish - Naum seemed to be heading for a draw. Surprisingly, Naum was not able to get a significant advantage and the pieces were being taken off the board until on move 50 only N vs N was left, Naum with an extra pawn. But Jellyfish blundered in the ending allowing Naum to win. This secures Naum's qualification.
Fire beat Arasan with ease, securing its qualification as well.
Chiron also qualified after beating the Baron in a rook ending playing black.
Now with only two more qualification spots, it was down to Vajolet2, Critter and Andscacs. Gaviota playing against Vajolet2 exchanged a rook for a knight and pawns early in the game, but when the position opened Vajolet2's rooks were a big advantage. Gaviota was forced to lose more material and lost the game. Vajolet2 was now tied with Andscacs and 0.5 points ahead of Critter with better SB.
Stockfish demolished Firefly as expected, and won the stage.
Critter - Andscacs was the last game of the stage. Critter needed a win to qualify ahead of Vajolet2, but Andscacs had other plans. Both evals reached zero on move 25, and from there it was a long boring game waiting for the pawn moves to stop long enough for adjudication. Vajolet2 and Andscacs are the qualifiers, Critter 9th on SB.
Featured game: Nirvana - Jonny
Stage 1b, round 15
Link to game on TCEC
Jonny was co-leader with Nirvana 0.5 points behind before their last match of the stage. Stockfish was going to win for sure so Jonny needed a win to stay at the top. The game reached a QRR vs QRR position at move 21 with evals close to zero. The most likely outcome was a draw, Jonny finishing second. After 40 moves the position was:
White could alternate pressure on the a6 and e6 pawns, the black queen confined to the king side too far to help with the a6 defense. Nirvana had a small advantage, and perhaps Jonny's defense was not perfect, allowing Nirvana to win the a pawn.
The b pawn now became a passer. Nirvana managed to advance the pawn slowly, keeping an eye on the black queen to avoid checks. Eventually Jonny had to block with the rook to avoid queening, and Nirvana could set up a winning position.
In the end it was Nirvana who came in second, Jonny only third. Both had a great first stage, we'll see in the next stage how much skill and luck were involved.