Season 16 superfinal games 51-60

After 60 games Stockfish leads 9-3 with 48 draws. Stockfish increases its lead to 6 points and it is probably going to win the match. AllieStein had a chance to win a game, it had a huge eval advantage but failed to convert the win.


There were a few exchanges after the start of game 51 and the engines started to shuffle early. After almost 50 moves there were several exchanges and the queen side opened. The engines slowly exchanged pieces until reaching an opposite color bishop ending and the game was adjudicated. In game 52 Stockfish pushed pawns on the king side and its king was quite exposed. After a series of exchanges the game reached a QR vs QB position on move 34, black two pawns up. After a while the pawns stabilized and Stockfish's eval came down to 0. Both kings were exposed and both engines could give checks, the game ended in a check repetition close to the 50-move draw.

There were many exchanges after the start of game 53 and only RBN vs RBN were left on move 23. Stockfish's eval came down to 0, AllieStein's eval remained too high for the draw rule for a long time. The engines slowly exchanged pieces and pawns until reaching a rook ending, the game ended in a tablebase draw on move 106. There were no exchanges at the start of game 54, AllieStein pushed pawns on the king side, it had more space for its pieces and its eval turned negative. The engines exchanged pawns on the king side and then mainly shuffled, Stockfish went a pawn up and its eval was close to 0 yet AllieStein's eval was around 1.5 (negative). AllieStein avoided a 50 move draw, the engines started to exchange pieces and open the position. AllieStein gave a rook for a knight, its bishop pair threatened the white king and evals jumped again. The game reached an unusual QN vs RBB position, AllieStein had an advanced passer that cost Stockfish its knight. At this stage AllieStein's eval was over 6, it peaked close to 8, yet incredibly Stockfish's queen seemed to be holding the defense by itself. One bishop was pinned and AllieStein could get no more than checks. Evals slowly came down, AllieStein lost its last pawn to avoid a 50-move draw. AllieStein continued to play but it lost its chance (if there was one). The game ended in a tablebase draw on move 242.

In game 55 the engines castled in opposite directions, Stockfish's eval was 0 almost from the start. Stockfish opened the queen side and placed its major pieces facing the white king. AllieStein opened the king side and defended its king. A series of exchanges led to a R vs BN imbalance and a QR vs QBN position on move 43. After exchanging queens only two white pawns remained in a 7-man position, AllieStein played on until a tablebase draw.

In game 56 Stockfish castled long and AllieStein pushed its queen side pawns. Evals jumped when AllieStein sacrificed a knight and opened the queen side. Many black pieces and pawns were facing the white king yet Stockfish was confident it could hold off an attack and its eval increased over 2.

Stockfish opened the b file and exchanged a pair of rooks, AllieStein doubled queen and rook in the open file. The black attack looked very dangerous yet Stockfish calmly played on the king side. For a while it seemed AllieStein was not sure how to proceed and evals slowly drifted down. Then AllieStein let go of a pawn in the center and evals jumped again.

Stockfish pushed its pawn to d7 to add a constant threat on the back rank. Then it gave a rook for a knight and pawn and exchanged all bishops. Only QNN vs QR remained, most of AllieStein's attack was over. It was no longer a piece behind but Stockfish still had a material advantage.

AllieStein removed the pawn on d7, Stockfish added two connected passers in the center to the passer on the king side. The white knights controlled the black pawns on the king side and AllieStein realized it had no hope, the game was soon adjudicated.

In game 57 AllieStein pushed two pawns to the 6th rank early, its eval went over 1. Stockfish exchanged queens and its eval dropped to 0, AllieStein's eval climbed over 1.5 and the engines started to shuffle. AllieStein avoided a 50-move draw, after a long series of exchanges only RN vs RB remained with pawns only on the king side. AllieStein was a pawn up but it was a doubled pawn and the king side pawns could not advance. AllieStein's eval kept the game alive, it ended in a tablebase draw on move 175. In game 58 queens were off early and AlllieStein was a pawn up. Stockfish concentrated on the queen side, the engines exchanged pieces and pawns until all the pawns on the queen side were gone and material was equal. The game reached a RBN vs RNN position and the engines started to shuffle, evals were close to 0 and the game was adjudicated quickly.

AllieStein's eval increased over 1 after the start of game 59. Both engines were in no hurry to attack, AllieStein gave a rook for a bishop and pawn, then created a passer in the center. The game reached a QRN vs QRR position, AllieStein's eval was over 1.5 and Stockfish's eval came down to 0. After some shuffling the engines exchanged a pair of rooks and AllieStein's eval came down as well. Both kings were exposed and the engines could give checks, the game ended in a check repetition.

In game 60 AllieStein pushed a pawn to a3 while the white king was on the other side, evals were over 1. Stockfish opened a file in the center and pushed two pawns on the queen side. After several exchanges Stockfish was a pawn up with a passer on the 6th rank.

Stockfish pushed the passer to the 7th rank where AllieStein blocked it with a rook. After exchanging the remaining minor pieces and pawns on the queen side the focus of the game became the white passer. One black rook could not move, AllieStein's only hope was a counterattack on the white king.

For a while there was no progress, then Stockfish offered a pawn on the king side. AllieStein accepted and evals jumped immediately. With the second black rook out of the way Stockfish could now move its rook to the 7th rank.

AllieStein's queen had to protect the b8 rook, Stockfish moved its rook forward and now it could also threaten the black king. AllieStein couldn't defend against all the threats and the game was soon adjudicated.

Season 16 superfinal games 41-50

After 50 games Stockfish leads 7-3 with 40 draws. Stockfish extends its lead to 4 points at the half-way point after two game pair wins. In both games there was a sudden eval jump after a mistake by AllieStein, but not after a no-think instamove, just not evaluating the reply correctly.

There was a change in the running parameters of AllieStein (hash and treesize) starting from game 45. These parameters should have been changed from the start of the superfinal but were not by mistake. It is not clear what effect this paramter change will have, I have not observed a change in AlllieStein's performance, and it lost game 46.

Games 41-42 started with a 20-ply book sequence in the Neo-Gruenfeld defense, Goglidze attack variation, where the engines castled in opposite directions. In game 41 AllieStein pushed a pawn on the king side, it removed all the black pawns there and reached the 7th rank. Stockfish hid its king behind the white pawn and attacked on the queen side. The white king was exposed, Stockfish sacrificed a knight and chased the king. AllieStein gave the material back, the game reached a QRN vs QRN position on move 34. The game was almost adjudicated before the engines exchanged queens and Stockfish got rid of the white passer. AlllieStein went two pawns up but Stockfish was sure it was fine, the 50-move rule forced AllieStein to give a pawn back and the game ended in a tablebase draw on move 167.

In game 42 both engines were more focused on defense and both kings were relatively safe. Evals remained around 1 as the engines exchanges many pieces. AllieStein tried to attack the queen side, evals came down as the black pieces moved forward leaving their king less defended. AllieStein completely missed Stockfish's move 37, though it thought more than 3 minutes.

Evals immediately jumped as Stockfish opened a file on the king side. AllieStein gave a rook for a knight to lower the risk to its king. The game reached a QR vs QB position, both kings were exposed, evals were around 4.

Stockfish cleared the queen side pawns, then started to give checks. The white major pieces threatened a back rank mate, Stockfish only had to be careful not to allow a perpetual check draw on the other side.

Stockfish captured a pawn and created passers on the king side, these together with the mate threat were enough for a win.

Games 43-44 started in the Two Knights defense, Polerio defense variation. White was a pawn up and black had a development advantage. In game 43 Stockfish's eval was 0 almost throughout the game. Stockfish regained the pawn, after exchanging queens AllieStein castled long. Neither engine attacked, the game reached a RRB vs RRN position on move 35. Stockfish had a king side passer, AllieStein had a pawn majority on the queen side. AllieStein thought it had an advantage for a short while, after exchanging a pair of rooks and several pawns evals came down again. The engines played almost 50 moves of a 7-man position before ending in a tablebase draw. In game 44 Stockfish kept its king in the center, its eval came down to 0 quickly while AllieStein's eval turned negative. AllieStein had the initiative though Stockfish was a pawn up, the engines reduced to a QRB vs QRN position. AllieStein pushed a passer to the 2nd rank, Stockfish blocked it and then gave a rook for a knight, created passers of its own and exposed the black king. After exchanging queens the engines continued the B vs R ending for 30 more moves before reaching a tablebase draw.

In game 45 AllieStein pushed its pawns forward and did not castle, it had a space advantage and eval around 0.5, Stockfish's eval was 0. The white king walked to the king side while AllieStein pushed its king side pawns. AllieStein sacrificed a knight and exposed the black king, with the white queen and two advancing passers attacking. The white king was alone, Stockfish moved its queen forward and found a perpetual check draw after a rook sacrifice.

In game 46 both engines waited a while before castling, and the f file was open by the time both engines castled short. Stockfish's eval remained mostly under 1, the engines exchanged most pieces and pawns. By move 32 only QRN vs QRB remained with 3 pawns each.

Stockfish pushed the e pawn one square forward and slowly arranged its pieces so it could push it further to the 7th rank. AllieStein delayed as much as it could but could not stop the pawn from reaching e7. Stockfish's eval increased to around 2, its next plan was to force the black rook out of the queening square. AllieStein's hope was to counter with an attack on the white king. Stockfish thought AllieStein's 44th move was a mistake and AllieStein immediately agreed, both evals jumped.

Nothing could stop the knight move to c7, the black rook had to move and AllieStein lost its bishop after Stockfish queened the pawn. The extra piece was enough for a win, the game was adjudicated a few moves later.

There were almost no exchanges at the start of game 47, AllieStein's eval was over 1. AllieStein pushed pawns on the queen side and drove the black pieces back. The engines opened the queen side and exchanged a pair of knights, AllieStein's eval jumped to around 2 and Stockfish's eval jumped over 1. However, after AllieStein opened the king side and sacrificed a knight for pawns Stockfish's eval dropped back to 0. The game reached a RB vs RBN position, AllieStein was 2 pawns up with 3 connected passers. Stockfish was confident it could hold, indeed the game continued for 60 moves until AllieStein lowered its eval. The game ended in a tablebase draw. In game 48 again there were only a few exchanges and the engines played behind the pawn lines. AllieStein controlled an open file on the queen side, it gave a rook for a bishop and managed to move its queen forward to the white back ranks. This only led to an exchange of queens and a RRB vs RBN position. The game ended in a check repetition.

Stockfish's eval was 0 almost throughout game 49. After a series of exchanges only RBN vs RBN remained on move 27. AllieStein had a pawn majority on the king side, and it managed to create a passer out of this. Stockfish defended easily, evals remained low and the game ended in a tablebase draw. In game 50 the engines gradually exchanged pieces and pawns and evals came down to 0. On move 39 the game reached a rook ending, AllieStein's eval turned negative and it took a long time until its eval came back down. The game ended in a tablebase draw after 118 moves.

Season 16 superfinal games 31-40

After 40 games Stockfish leads 5-3 with 32 draws. The gap between the engines stays 2 points. AllieStein lost another game due to a judgment error made without proper consideration. Its win shows that AllieStein can sometimes understand a long term advantage better than Stockfish.


Games 31-32 started with a 24-ply book sequence, with white a rook up and a knight trapped in the corner, and the black king uncastled after moving. In game 31 Stockfish captured the knight and pushed pawns on the king side facing the white king. Its eval dropped to 0 as it opened the king side, the two black knights gave checks and AllieStein avoided a repetition. To get its king out of trouble AllieStein gave two pawns, Stockfish sacrificed a rook to finish the game in a check repetition.

In game 32 both engines did not castle. AllieStein pushed pawns on the king side and the white king walked to the queen side. After capturing the white knight in the corner AllieStein planned in its PV to capture the pawns on the king side. The plan included a knight sacrifice and allowing Stockfish to push a passer on the queen side. AllieStein went ahead with this and Stockfish played along. The engines' PVs disagreed on move 32, AllieStein made its move with 3 seconds thinking time.

Stockfish's eval jumped over 1.5 and climbed fast. AllieStein bet the game on the value of the three advanced passers in the center. Stockfish's advanced passer together with mate threats and attacks on pieces forced AllieStein to defend. AllieStein only realized it was in trouble on move 39.

After exchanging queens Stockfish captured one of the passers. The threat of the black central pawns was smaller, Stockfish could block them with its bishops. The extra rook was enough for a win, the game was adjudicated a few moves later.

AllieStein started game 33 with an eval under 1. The white king walked to the queen side, AllieStein's eval increased over 2 while Stockfish's eval remained low. AllieStein tried to press on the queen side but nothing came out of it, Stockfish's eval dropped to 0. The queen side pressure was released after several exchanges, Stockfish then gave a rook for a bishop and used a queen and knight combination to threaten the white king. The game reached a QRN vs QBN position and ended in a perpetual check draw. In game 34 Stockfish castled long, its eval went over 1. AllieStein had a bishop pair but in a closed position the two white knights were more useful. The pawn lines stabilized and the engines started to shuffle. Stockfish avoided a 50-move draw and its eval came down. The engines reduced to a N vs B ending and the game ended in a tablebase draw.

The engines castled in opposite directions in game 35. AllieStein's eval increased over 3 as the engines started to exchange pieces, its eval peaked around 4. The game reached a RN vs RB position with white a pawn up. Stockfish's eval came down to 0 and the engines started to shuffle. AllieStein created passers on the queen side and Stockfish had a passer on the king side. Stockfish gave its bishop to stop a white passer, AllieStein gave a rook to stop a black passer, the remaining N vs R ending was a draw. In game 36 AllieStein kept its king uncastled, Stockfish's eval was a little over 1 and did not increase. AllieStein opened the king side and the white king walked back to the center, Stockfish went up a pawn but its eval came down to 0. After a long series of exchanges only RRN vs RRB remained, Stockfish ended the game with a check repetition.

Evals were low from the start of game 37. AllieStein gave two pawns but had a bishop pair, the game reached a RBB vs RNN position on move 22. In the next 35 moves the engines exchanged a pair of pawns, AllieStein captured a black passer and then the engines reduced to a B vs N ending. The game should have ended by the draw rule on move 44, the game eventually ended on move 90. In game 38 Stockfish pushed pawns on the king side and its king became exposed. AllieStein's eval turned negative, it tried to press on the king side but Stockfish kept the files closed. The game reached a rook ending on move 48. Black's extra pawn was not enough, the game was adjudicated 25 moves later.

Games 39-40 started with a 20-ply book sequence in the Frence defense, Boleslavsky variation, where the engines castled in opposite directions. In game 39 AllieStein pushed a pawn to h6, a thorn pawn, its eval over 1.5. Stockfish pushed pawns on the queen side, it was surprised when AllieStein remained passive. Stockfish captured on b2 and the white king hid behind the pawn, AllieStein's eval jumped over 2.5.

AllieStein's eval climbed quickly, the black DS bishop was blocked and the white knight on d6 was a threat for the black pieces. The engines exchanged queens and Stockfish could no longer threaten the white king. Stockfish opened the long diagonal to find space for its bishop and to protect the b2 pawn, the only safe square it found was in the corner.

AllieStein soon captured the two black pawns on the b file. The trapped bishop could not get out of the corner, and the other black bishop on d5 was blocking the white rooks from attacking the back ranks.

AllieStein used its knight to drive the d5 bishop away and the rooks came forward. AllieStein captured a third pawn, the game was adjudicated 10 moves later.

There were many exchanges after the start of game 40, only RRN vs RRB remained on move 27. The pawn lines stabilized and the engines shuffled for a while as evals slowly came down. Stockfish moved both its rooks to the 7th rank and the game ended in a 3-fold repetition.

Season 16 superfinal games 21-30

After 30 games Stockfish leads 4-2 with 24 draws. AllieStein lost another game with a blunder caused by ignoring a winning move by the opponent, as well as not thinking long enough before making a move. It immediately came back with a win, this time showing a better understanding of the position than Stockfish.

The engines castled in opposite directions in the book sequence of games 21-22. AllieStein started game 21 with an eval over 1 and it stayed at that level for a long time. Stockfish pushed pawns on the queen side and opened files facing the white king. After several exchanges only RRB vs RRB remained on move 25, white had a pawn majority on the queen side. AllieStein managed to create a queen side passer, other than that the engines mainly shuffled. The game was adjudicated when AllieStein lowered its eval. AllieStein pushed pawns on the queen side in game 22, this time the engines locked pawns and kept the queen side closed. Stockfish pushed pawns on the king side but couldn't open files there either. The engines mainly shuffled, after the last knight was off Stockfish captured a pawn but could not improve. The game ended in a 50-move draw.

There were no exchanges after the start in game 23, the first exchange occured on move 22. The engines continued to play mostly behind the pawn lines, on move 39 the last knights were exchanged and evals were close to 0. The engines gradually exchanged pieces and pawns, on move 58 only QRB vs QRB remained, white had 2 pawns and black had 1. The engines mostly shuffled and gave checks, the game ended in a 50-move draw. In game 24 there were again no exchanges. The pawns in the center and the queen side were locked, Stockfish's eval gradually increased until it was over 1.5 but its plan was not clear. On move 37 the first pawn was taken, AllieStein pushed a pawn to the 2nd rank while Stockfish gave a knight for pawns and opened the king side, evals dropped to 0. AllieStein traded RB for Q, its king was exposed and the game ended in a check repetition.

In game 25 AllieStein kept its king uncastled, its eval slowly climbed over 1 while Stockfish's eval dropped to 0. The engines opened the king side and the black king was exposed, after many exchanges only QR vs QR remained with AllieStein a pawn up. The white king was also vulnerable and Stockfish started giving checks. Eventually the engines exchanged queens and the game was adjudicated.

Game 26 started similarly, Stockfish kept its king uncastled and pushed pawns on the king side. On move 20 AllieStein captured a knight after thinking less than a second, this opened the h file and Stockfish's eval jumped over 2.

The king side opened and the black king was exposed. AllieStein continued to follow its PV, it totally missed Stockfish's move 25, seeing the mate threat too late.

Stockfish captured the black queen and the game ended in mate on the board a few moves later. A game pair win for Stockfish.

AllieStein's eval started over 1 in game 27 and slowly increased. Stockfish opened a file in the center, most pieces stayed on the board and neither engine seemed ready to attack. The main difference between the engines was that AllieStein had a bishop pair and Stockfish had a knight pair.

The engines shuffled for a while and exchanged all rooks through the open file. AllieStein's eval jumped over 3, after exchanging queens the game reached a BB vs NN position. Stockfish continued to be calm with an eval below 1.

Stockfish's eval started to increase. It allowed AllieStein to capture a pawn on the king side and in return trapped a bishop in the corner. AllieStein's eval shot up and after arranging its pieces it exchanged the trapped bishop with a black knight.

The white king advanced and Stockfish couldn't protect the pawns on both sides. AllieStein captured a second pawn and the game was adjudicated a few moves later.

In game 28 evals started below 1 and gradually came down. Both central files opened, this time AllieStein kept one bishop. The engines used the open files to exchange a pair of rooks and queens as well. The engines continued to exchange pieces until only B vs N remained. AllieStein's eval turned negative but it had no real advantage. The game ended in a 50-move draw. AllieStein comes right back with a game pair win.

Games 29-30 started with a 20-ply book in the QGD opening, Rubinstein variation, with the kings castled in opposite directions. In game 29 there was a long series of exchanges and most pieces were gone. By move 28 only Q vs QB remained, white 3 pawns up for the bishop. AllieStein pushed pawns forward, it captured the bishop and allowed Stockfish to draw with check repetition. In game 30 AllieStein gave a pawn and opened the queen side, the pieces stayed on the board longer. AllieStein regained the pawn and the engines exchanged pieces until reaching a QRN va QRN position, evals coming down to 0. The black king was exposed and Stockfish gave checks, the game should have been stopped twice by the draw rule but the engines played on. The game ended with a check repetition draw.

Season 16 superfinal games 11-20

After 20 games Stockfish leads 3-1 with 16 draws. AllieStein's losses came from two blunders, where it realized its mistake almost immediately. It needs to improve its analysis to avoid these mistakes.


AllieStein had an eval over 1 at the start of game 11. There were very few exchanges, the engines played behind their pawn lines and AllieStein had a space advantage. Stockfish gave a pawn and opened a file on the queen side, evals came down and after a series of exchanges only QN vs QB remained. The queens were exchanged and the engines continued to play 40 more moves before adjudication.

In game 12 there were again almost no exchanges after the start. Evals started below 1 and were more or less stable. AllieStein pushed pawns on the king side, this added space for its pieces while weakening its king. A pawn exchange opened the king side, evals were low.

Stockfish's eval jumped over 2 and AllieStein's eval jumped a move later. The black queen became trapped in front of the pawns and Stockfish traded a rook and a bishop for it. The advancing black pawns looked dangerous but evals were over 5.

AllieStein continued to fight, it pushed one pawn all the way to promotion and gained some material for it. However it was only temporary, Stockfish reduced to a QN vs RBN position with 3 queen side passers and the game was adjudicated.

In game 13 Stockfish walked with its king to the king side without castling. The center was blocked, AllieStein kept its king uncastled, its eval increased over 2 and Stockfish's eval went over 1. The queen side opened, AllieStein pushed pawns on the king side. Stockfish placed its pieces in a defensive structure, after a few exchanges only QBB vs QBN remained and the engines started to shuffle. AllieStein couldn't break the fortress, the game ended on move 137 in a 50-move draw.

In game 14 AllieStein let Stockfish capture two pawns on the king side while it captured two pawns on the queen side. Stockfish eventually castled its king, away from most black pieces. AllieStein kept its king exposed in the center, evals came slowly down.

Stockfish opened files in the center and on the king side, evals came down to 0. All the major pieces were active and the kings were exposed, there was always the possibility of a perpetual check draw. AllieStein was sure Stockfish was about to capture the c3 pawn, it thought 2 seconds and missed Stockfish's reaction with eval over 5.

Analysis shows that if AllieStein takes the bishop on c5 with its pawn it loses the e4 rook and the game reaches a RR vs RN losing endgame. Taking with the queen is mate in 3, running with the king leads to losing the queen and a quick mate. AllieStein chose to block the check with its knight, and after a few exchanges the game was adjudicated as Stockfish was about to capture a rook. A huge blunder by AllieStein.

Both kings remained uncastled in game 15. AllieStein pushed pawns on the king side, it gave two pawns and opened the king side leaving its king exposed. After many exchanges only QBN vs QBB remained, AllieStein got one pawn back and attacked the black king. Stockfish sacrificed a bishop and starting giving checks. There were a few more exchanges but in the end AllieStein couldn't escape the checks and the game was adjudicated on move 104. In game 16 Stockfish pushed pawns on the king side and kept its king uncastled, while AllieStein castled its king. The engines gradually exchanged pieces ane evals were low, Stockfish went a pawn up and created a queen side passer. For a short while evals jumped over 2 but it was a false alarm. AllieStein threatened the exposed white king using the back ranks, the engines reduced to QN vs QB position and Stockfish gave checks until adjudication.

In game 17 there were almost no exchanges after the start. Then in a long series of exchanges almost all the pieces were removed and RNN vs RBN remained on move 30. Stockfish had a queen side passer, it pushed it to the 2nd rank but there AllieStein captured it. The engines exchanged a pair of knights and started to shuffle. Eventually the rooks were exchanged and the game ended in a tablebase draw. Stockfish started game 18 with an eval around 1 that slowly increased. Again there were no exchanges after the start and then a long series of exchanges, by move 33 queens were off and most queen side pawns as well. Evals were over 2 and still increasing. Stockfish managed to capture a bishop for pawns and the game reached a RB vs R position. Stockfish's eval was over 3 yet AllieStein found a fortress that Stockfish couldn't break. The white king stayed in the corner and the white pieces were not strong enough to capture a pawn or attack the black king. The game ended in a 50-move draw.

Game 19 was a miniature that ended in a repetition draw on move 16 after less than 30 minutes. In game 20 there were no exchanges after the start, on move 27 Stockfish opened a file in the center and then captured a rook for a bishop. Evals stayed below 1, AllieStein blocked the open file and the pawns stabilized. On move 42 the last knights were exchanged and the engines started to shuffle. Stockfish's eval was over 1 but it could make no progress, the game ended in a 50-move draw.

Season 16 superfinal games 1-10

After 10 games the score is 1-1 with 8 draws. In the premier division Stockfish beat AllieStein 3-0. However AllieStein updated its net and it appears to be better in the superfinal. Hopefully Stockfish will be stable in the superfinal, I wouldn't want crashes to affect the outcome of the match.

Games 1-2 were played without a book start sequence. Game 1 was a French opening, Steinitz variation. Queens were off early and both engines did not castle. AllieStein went a pawn up and the engines started to shuffle in a closed position. The 50-move draw was avoided twice before the engines lowered their evals for adjudication by the draw rule on move 137. Game 2 was a Semi-Slav defense. The engines opened files on the queen side and exchanged most pieces, only QB vs QN were left on move 24. After exchanging queens AllieStein's eval turned negative, the endgame was stopped by a 50-move draw.

Games 3-4 were a King's Indian defense. In game 3 AllieStein broke the diagonal pawn lines and allowed Stockfish to create a passer in the center. The engines mostly shuffled from move 19, evals increased as AllieStein had more space and Stockfish's king was vulnerable.



AllieStein used the open long diagonal for a constant mate threat, then pushed the a pawn forward to the 6th rank. The black pieces were forced to defend passively. 



AllieStein attacked on the king side, Stockfish gave a rook for a bishop and exchanged pieces until only RR vs RN remained.



The material advantage and passer on the 7th rank were enough for a win. First blood in the superfinal for AllieStein.

In game 4 Stockfish kept the diagonal pawn lines and this allowed AllieStein to create pressure on the king side, its eval turned negative. AllieStein opened the king side, Stockfish countered on the queen side and gave a rook for a bishop. after many exchanges the game reached a QBN vs QR position, the king side attack was mostly over and the white king escaped to the center. The game ended in a perpetual check draw. AllieStein wins the first game pair.

Games 5-6 started with a 19-ply book sequence in the Sicilian, Paulsen variation. In game 5
the engines castled in opposite directions, AllileStein pushed pawns on the king side and thought it had an advantage. Stockfish surprised with a rook sacrifice that opened the queen side, forcing a quick perpetual check draw.

Game 6 started similarly, Stockfish pushed a pawn to h6 and caused the long diagonal to open, weakening the black king. AllieStein countered on the queen side but was not able to break Stockfish's defense or to force a perpetual check draw. Stockfish moved a bishop to g7 in front of the black king, its eval increased over 2.

Stockfish opened the f file and threatened immediate mate. AllieStein's pieces were far on the other side, Stockfish traded its queen for a rook and bishop, removing the last defenders. Only RRB vs QR remained, Stockfish's eval jumped over 14.

Black had to use all its pieces to avoid mate on f8. Stockfish created a passer on the queen side and the game was adjudicated, PVs showed that after exchanging all pieces on f8 black can't stop the passer. Stockfish wins a game pair and equalizes.

Queens were off early in game 7 and Stockfish kept its king in the center. After a series of exchanges only RR vs RBN remained, most of the pawns were gone and both kings were exposed. AllieStein's eval stayed over 1.5 for a long time, it created a king side passer and managed to push it forward while Stockfish captured the remaining white pawns. AllieStein sacrificed its rooks and queened the pawn, this led to a drawn Q vs RB ending. In game 8 AlllieStein castled its king and the position remained closed. Evals came down to 0 after files were opened on both sides, the game reached a RN vs RB position and ended in a tablebase draw.

Games 9-10 were a King's Gambit Accepted variant. There were many exchanges after the start of game 9, evals came down to 0 and the game reached a rook ending on move 31. AllieStein thought it had a small advantage, the game continued for 40 moves until it lowered its eval for adjudication by the draw rule. In game 10 the pieces stayed on the board longer, both kings were uncastled in the center and queens were off early. Stockfish's eval was 0, AllieStein thought it had an advantage. The game reached a RBN vs RBN position on move 42, a N vs B ending on move 61, and ended in a tablebase draw.

Season 16 premier division final results

Final crosstable

Stockfish and AllieStein qualify for the superfinal. Stockfish survived without crashing a third time and even finished first. Leela finished third and will not defend its title, despite it being the only undefeated engine and the only engine to beat Stockfish in the division (not through a crash).

The fact that Stockfish was not disqualified means that KomodoMCTS and ScorpioNN are relegated to league 1 next season. ScorpioNN and Stoofvlees started season 16 in the qualification league, both reached the premier division but only Stoofvlees managed to stay in the division for next season.

Leela fans will be disappointed that Leela did not qualify for the superfinal. For AllieStein this will be a first superfinal appearance, in only its second TCEC season. Stockfish is still a top engine despite the NN revolution. In the premier division Stockfish beat AllieStein 3 times. In the superfinal Stockfish will fix its bug and AllieStein will have a new version, I hope to see a competitive match.

A few interesting games

The leaders' scores with 7 games left are: AllieStein +9, Stockfish +8, Leela +6. Stockfish still has 2 crashes, one of those was a gift to AllieStein. Leela is without a loss but needs wins to close the gap.

ScorpioNN - Leela: The game reached a QRR vs QRR position with most pawns on the board. After some suffling the engines exchanged queens, then ScorpioNN blundered and allowed Leela to capture two pawns and create passers on the queen side. ScorpioNN had a king side passer, both engines lost a rook to remove a passer and this left a winning rook ending for Leela. Leela won this opening from both sides.

Houdini - AllieStein: AllieStein had a pawn majority on the queen side and evals turned negative. AllieStein's eval increased quickly after the majority became a supported passer on the 3rd rank. The engines gradually exchanged pieces until only RB vs RN remained, AllieStein lost the queen side passer but was a pawn up with a central passer. AllieStein took its time and didn't push the pawns. The engines shuffled a lot, Houdini lost patience and pushed a pawn. AllieStein captured the pawn and went back to shuffling. The game was finally adjudicated on move 180. A double win for AllieStein in this opening.

ScorpioNN - Stockfish: ScorpioNN gave a rook for a knight early, the position was static and the engines started to shuffle. At move 104 Stockfish's eval jumped over 2 (negative), ScorpioNN blundered with seconds left on its clock. Within a few moves Stockfish reduced to a QB vs QR position, its eval over 13. ScorpioNN gave its queen for a rook to stop mate on the back ranks, a win for Stockfish.

Leela - Komodo: Leela gave a pawn on the queen side and evals started to increase. Komodo sacrificed a bishop for pawns and opened the king side, then gave a knight and exchanged queens. The game reached an unusual RBNN vs RN position with black 4 pawns up. Leela was very patient and Komodo's eval increased slowly. It took Leela 30 moves to capture 3 pawns, and another 30 moves for evals to be high enough for adjudication.

Stoofvlees - AllieStein: Stoofvlees had an eval advantage from the start. The engines mainly shuffled behind their pawn lines. Stoofvlees opened the center and tried to attack the black king, it forgot that its own king was exposed and AllieStein's eval suddenly jumped over 7 (negative). AllieStein's attack was lethal and Stoofvlees lost its queen to defend its king. The game was adjudicated a few moves later. Another double win for AllieStein.

Only 4 games left, the top of the table is: AllieStein +11, Stockfish +9, Leela +8. Leela is only 0.5 points behind, Stockfish and Leela drew their game, AllieStein with two more double wins is leading comfortably.

Stockfish - AllieStein: see featured game below.

Leela - Houdini: Leela opened a file on the king side and the black king ran to the center. Evals gradually increased as the engines exchanged pieces. Houdini went a pawn up and the game reached a RN vs RN position, evals were close to 2. Leela's rook was on the 7th rank and it had an advanced passer, Houdini was able to stop the passer but by then Leela was two pawns up. The game went on for 35 more moves before adjudication.

Only 2 games left, the top of the table is: AllieStein +10, Stockfish +10, Leela +9. AllieStein lost to Stockfish for the third time in the division, the race for the superfinal is wide open. Leela and AllieStein drew their game, the remaining opponents of the leaders are lower ranked engines.

Houdini - Stockfish: Houdini's queen captured two pawns on the queen side, Stockfish gave a rook for a bishop and the game became wild. Both kings were exposed and uncastled, Stockfish lost another knight but Houdini had a trapped rook and its king was in danger. Houdini gave the material back and the game reached a QRB vs QRB position, Houdini was two pawns up but Stockfish's king was safe and this was a huge advantage. It took Stockfish 30 moves to capture 4 pawns while chasing the white king, enough for a win. Stockfish won both games in this opening.

Final scores: Stockfish +11, AllieStein +10, Leela +9. Both Leela and AllieStein drew their last two games, Stockfish survived to the end and even finished first despite having two crashes.

Featured game: Stockfish - AllieStein
Premier division, game 158
Link to game on TCEC

Stockfish had an eval advantage from the start. The engines castled in opposite directions, Stockfish pushed pawns on the king side facing the black king. AllieStein countered with pawns on the queen side and then sacrificed a knight to expose the white king. Stockfish's eval increased over 1.5.

Stockfish opened the king side and pushed a pawn to the 7th rank. AllieStein opened a file on the queen side and threatened mate, however Stockfish was not intimidated and its eval jumped over 9.

Stockfish gave a knight to defend its king, but its king side attack put AllieStein's king in real danger. AllieStein lost material so its king could escape, and Stockfish queened its passer. 

Stockfish had two queens attacking, the game ended with mate on the board a few moves later.