ChessBrain and Xiphos promote to division 2, Senpai and Wasp are relegated to division 4.
ChessBrain dominated the division, a big improvement compared to season 11 where it finished 7th in division 3. The fact that it is written in Visual Basic is also a little bizzare. Xiphos was also a surprise, it started in division 4 as a new engine and finished second behind Ethereal. In division 3 it also finished 2nd, but Ethereal only 4th two points behind.
Pedone crashed once in the fourth double round, and there was some concern about its stability after it had two crashes in season 11. However Pedone managed to finish all of its remaining games and to be a real candidate in the promotion race.
The race for 2nd place was exciting, there were 4 candidates with a good chance of promotion in the final rounds: Xiphos, Pedone, Ethereal and Bobcat. Xiphos was ahead, but it had to play ChessBrain in the last round and it lost its head to head games to both Pedone and Ethereal, so it couldn't afford a tiebreak. In the end it was Xiphos' better scores against the lower ranked engines that gave it the advantage, and the surprising win against ChessBrain sealed its promotion.
The TCEC website is being updated, with a new GUI being tested. I'm not sure I'm going to like the new version, it still doesn't have the full functionality of the current GUI but that is work in progress, Having the two sites running it is clear that the new GUI is much faster, the current GUI lags by 10s of seconds. We'll have to get used to the new I suppose, can't stop progress.
Division 2 will start soon, probably a day or two break judging by the previous divisions. ChessBrain and Xiphos will be joined by Hannibal, Nirvana, Texel, Arasan, Fritz and Vajolet. I expect another exciting race for promotion. Can Xiphos promote a third time, or will it be relegated back to division 3?
Final 3 rounds, fight for second place:
The standings at the start of round 12 were: Xiphos 14, Pedone, Ethereal, Bobcat 12.5.
Bobcat managed 0.5/2 points from its double game against ChessBrain. The first game reached a RN vs RN position on move 26, Bobcat held as black. In the reverse ChessBrain attacked with a pawn storm on the king side, Bobcat's position collapsed and the game was quickly over.
Pedone with a big 1.5/2 over Xiphos. The first game ended in a draw. The second game reached a RN vs RB position on move 31 with evals close to 0, then Pedone in black won a pawn and reduced to a rook ending, its eval jumping over 2. Xiphos sacrificed pawns to get a passer to the 7th rank, this cost Pedone its rook. However the 4 king side passers were stronger than the remaining white rook. With this win Pedone improves its chances, closing the gap to only half a point.
Ethereal with two draws against Senpai, only 1/2 points. A missed chance for Ethereal.
After round 12 the standings were: Xiphos 14.5, Pedone 14, Ethereal 13.5, Bobcat 13
Xiphos beat Bobcat with 1.5/2. In the first game Xiphos as black had a bishop pair and a better pawn structure, it outplayed Bobcat slowly. The black king found a safe square behind a white pawn, Xiphos captured a pawn and created an unstoppable passer. The second game reached a QB vs QB position on move 31, Bobcat had a central passer and an eval advantage but Xiphos held the draw. Bobcat is out of the race.
Pedone and Ethereal needed wins to get closer to Xiphos. The first game was a 20 move miniature that ended in a perpetual check. The second game reached a RN vs RN position on move 24, Pedone used its tablebase knowledge to reduce to a RN vs R draw. A disappointing result for both engines.
Going into the final round the standings are: Xiphos 16, Pedone 15, Ethereal 14.5
Xiphos had ChessBrain as its last opponent. Xiphos as black had a pawn advantage and a central passer, ChessBrain defended well and held the draw. In the reverse game ChessBrain attacked on the king side, but was not effective. Xiphos had a central passer that had to be watched, at the right moment Xiphos started a series of exchanges that led to a Q vs RB ending. Xiphos was two pawns up and winning. A surprise result, only the 2nd loss for ChessBrain in the division, Xiphos clinches the second promotion spot.
The remaining Ethereal and Pedone games were less interesting now that the race was over. Ethereal drew twice against Bobcat. Pedone lost as black against Nemorino, and then won as white.