Season 17 league 2, final results

Final crosstable

After removing Wasp games (crashed out) the scores are: Fire +16, DefenChess +13, RubiChess +7, Vajolet +5, Pedone +3, Nemorino Winter 0, PeSTO Gull -1, Texel -2, Minic Demolito -4, iCE -8, Igel -9, Pirarucu -15, Wasp DQ.

Fire, DefenChess, RubiChess and Vajolet advance to league 1.The race for 4th place was only determined in the last round. Fire returns to league 1 with the previous AB version, DefenChess advances for the second time this season.

Minic, Demolito, iCE, Igel, Pirarucu and Wasp relegate out of league 2. Five engines that advanced from qualification go back down, Wasp crashed out. Minic crashed in a won position against Nemorino, without this crash both would have had the same score as Texel, not sure which engine would have relegated then. Winter and PeSTO managed to stay in league 2 after advancing from qualification. Gull survived another season, perhaps the next one will be its last. 

The 4 promoting engines are planned to join KomodoMCTS, Laser, Ethereal, Xiphos, Chiron, Andscacs, Fizbo, ChessBrain, Booot, rofChafe and Arasan in league 1. According to the current season 17 engine page Jonny needs a stable update to play in the league. Other engines may fail testing, as we have seen in league 2. More engines may yet promote from league 2, the list will be finalized in a few days.

The GPU league 1 is getting closer and there has been no update about the GPU hardware planned for this season, or the candidate engines.

Notable games

Game 138, DefenChess - Vajolet: Vajolet gave a knight for pawns and attacked the white king. DefenChess defended its exposed king and slowly reduced to a RBN vs RB position, then advanced passers forced Vajolet to give its bishop and the game was over.
Game 149, RubiChess - Pirarucu: Pirarucu's king was exposed in the center, and its king side pieces were stuck. RubiChess gave material and attacked, winning in 22 moves.
Game 152, Vajolet - Nemorino: Vajolet gave a knight to open the queen side and expose the black king. Nemorino tried to give back material, the game reduced to a QR vs QBN position. Advancing passers and the exposed king were enough to give Vajolet the win.
Game 157, Pirarucu - Wasp: The game reached an unusual QB vs RNN imbalance, white with no pawns to black's six. The white pieces were very strong and Wasp gave material to reduce to a QR vs RBN with 5 pawns. Pirarucu used mating threats to capture the knight and was strong enough to win. Too bad Wasp already crashed out and this first win for Pirarucu will not be part of the final score.
Game 159, PeSTO - Demolito: Demolito gave a rook for a bishop and opened the position, PeSTO's king was exposed but it had an advancd passer. PeSTO gave its queen and promoted the pawn, it used back-rank threats to capture a piece and win.

Scores after 20 rounds: Fire +11, DefenChess +9, RubiChess +7, Pedone +6, Vajolet +5, Nemorino +1, PeSTO 0, Winter Gull -1, Texel -2, iCE Minic -4, Demolito -5, Igel -9, Pirarucu -13, Wasp DQ. Wasp crashed for the third time and is disqualified, all its games are ignored. The top 5 engines are in the race for 4 promotion spots. Three of the bottom 6 engines still have a chance of surviving,

Game 180, Demolito - Igel: Demolito gave two knights for a rook and its major pieces were less effective with many pawns on the board. Igel pushed pawns on the king side, Demolito gave material to try to stop them, enough for a black win.
Game 184, Texel - Pedone: Texel was up a pawn in a RB vs RN position. It gradually improved its position and then captured two more pawns for the win. Pedone's first loss in the league.

Scores after 24 rounds: Fire +13, DefenChess +10, RubiChess +7, Pedone Vajolet +5, Nemorino +1, Winter 0, PeSTO Gull Texel -1, Minic -4, iCE Demolito -6, Igel -9, Pirarucu -13, Wasp DQ. Pedone and Vajolet are tied in 4th place after Pedone lost its first game. At the bottom Demolito and iCE are 2.5 points away from survival, Minic still has a small chance but will lose tiebreaks due to its early crash. Only 6 rounds to go.

Game 197, Demolito - Nemorino: Demolito was up a rook for a bishop and Nemorino's bishop pair was not enough as compensation. Demolito created a passer in a RN vs BB position, Nemorino had to lose material to stop it.
Game 198, Gull - Vajolet: Gull played better in a RBB vs RBN position, it used a pawn majority on the queen side to queen a pawn while Vajolet captured a bishop and the remaining 5 pawns. Gull stopped the black pawns to win.
Game 213, Fire - Vajolet: The game reached a RBN vs RBN position, Fire's eval increased very slowly. It took more than 50 moves to capture a pawn, another 20 moves to reduce to a winning RB vs RN ending two pawns up.
Game 214, Demolito - Pedone: Demolito went up a pawn with an advanced passer early in the game. While Pedone focused on blocking the passer Demolito developed a deadly attack on the black king. Just before the game was adjudicated Pedone crashed.

Scores after 27 rounds: Fire +14, DefenChess +11, RubiChess +7, Pedone +5, Vajolet +3, PeSTO Nemorino 0, Winter Gull Texel -1, Minic -3, Demolito -4, iCE -7, Igel -9, Pirarucu -14, Wasp DQ. Three rounds to go. Vajolet is a point away from 4th place Pedone, still with a chance to promote, and with a tiebreak advantage after Pedone crashed. Minic and Demolito improved their chances of survival, but since they both have games against Wasp effectively they only have two games left to close the gap. iCE has only a theoretical chance of survival at this stage.

Game 220, Pedone - Fire: Fire went a pawn up late in the game in a QRN vs QRN position. After a long shuffle Fire exchanged queens, it took 30 more moves to reduce to a winning knight ending.

After round 28 Pedone (+4) is only 0.5 points ahead of Vajolet (+3). There is no change at the bottom of the table, Demolito had a material advantage against Texel but couldn't convert. 

Game 225, Igel - Minic: Igel gave a knight for 4 pawns and created 2 advanced passers. Minic was busy trying to stop the passers, it captured one but lost material to stop the other and the game was over.
Game 227, iCE - Nemorino: iCE was better in a QRR vs QRR position, it reduced to a rook ending a pawn up and reached a tablebase win. First win for iCE in the league.
Game 229, Winter - Pedone: Winter was up a rook for a knight, its king exposed in the center was Pedone's compensation. Winter gave the material back and reduced to a RB vs RB position with white a pawn up. After exchanging rooks the extra pawn was enough for a win.

After round 29 Vajolet (+4) overtakes Pedone (+3), the last round will determine which of them will finish 4th. The situation at the bottom is: Winter 0, PeSTO Nemorino Gull -1, Texel -2, Minic Demolito -4. Demolito's last game is against Wasp so it cannot escape relegation. Minic needs a win to reach Texel, and only if Texel crashes does Minic have a chance in the tiebreak (not sure what happens then, it is very close).

In round 30 Minic drew and relegated, Pedone drew and lost the chance to promote, then Vajolet won and increased the gap to a point.

Season 17 league 2 statistics

A summary statistics table of previous stages and seasons. 

Draw rate, wins


Final draw rate was 56.3%.


Game termination

The three most common game termination causes were:


34.2% - TCEC win rule
30% - TCEC draw rule
21.7% - SyzygyTB


There were 6 crashes in the stage: Wasp crashed 3 times and was disqualified, Minic, Pirarucu and Pedone each crashed once.

Moves per game


Median= 58.8
Average= 63.8

There were 23 games longer than 100 moves, the longest was 141 moves (PeSTO - Igel, game 87, and Minic - RubiChess, game 201, both draws).

Time per game (hours)
 
Median= 1:01
Average= 1:01

Openings

There were 6-move book openings in this stage chosen by Cato. The first letter of the ECO codes was distributed as follows:


The engines had less freedom to choose the opening variant, 84.2% of the game pairs repeated the same ECO code twice, and 76.7% repeated the same opening variant. In all but one of the game pairs the ECO first letter was repeated twice.

Reverse pairs, wins


Reverse pairs, same moves 



Pairs of reverse games diverged very quickly, 39.2% diverged immediately out of book, 73.3% of the pairs diverged at most after 1 move. The longest repeated sequence of moves was 14 plys (Igel - iCE games 90 and 210, Two knights defence, two draws)

Season 17 league 2, after 15 rounds

Before the start of league 2 chess22k and Fritz crashed in testing, apparently they are not compatible with the new hardware. As a result two more engines from the qualification league were promoted to replace them, Minic and PeSTO.

The plan is to have 6 relegations and 4 promotions in League 2, there may be changes after league 1 testing.

Scores after 15 rounds
Fire +8, DefenChess +6, Pedone +5, Vajolet RubiChess +3, Nemorino +2, Winter 0, Texel Wasp Minic Gull -1, Demolito -2, PeSTO iCE -3, Igel -7, Pirarucu -8.

At the top of the table Fire, DefenChess and Pedone are without loss, all have a good chance of promoting to league 1. Fire returned to its AB version after its NN version failed miserably in season 16, which led it to league 2. Fire AB played in the premier division for many seasons, it is likely to stay in league 1 after promotion. The newcomer DefenChess continues its success in this league. There are at least 3 contenders for the 4th promotion spot, though recall that Nemorino got a free point from a crash in a losing position against Minic.

The last 5 engines in the table played in the qualification league. Igel and Pirarucu are surely on their way back down, the other engines may still avoid relegation. Gull is facing relegation like in season 16, in which case it will stop playing in TCEC because it is "abandon-ware".

Wasp crashed twice so far and is in serious danger of disqualification. Minic crashed once in round 3, but has been stable since.

Notable games

Game 5, Texel - PeSTO: 13 move miniature, 3-fold repetition.
Game 12, PeSTO - RubiChess: The game reached a RRB vs Q position, black with connected passers, one on the 2nd rank. Evals were 0, but RubiChess' play was not accurate. PeSTO used the bishop to stop the white passers, and its rooks slowly took over the game, it took 40 moves for the engines to agree PeSTO winning.
Game 17, Nemorino - Minic: Minic surprised - after qualifying 7th - when the game reached a RB vs RB position with black a pawn up. It then surprised again when it crashed just before securing the win.
Game 50, Texel - Vajolet: Vajolet gave a rook for a knight and pawns early in the game, but its passers were not strong enough. Texel reduced to a RB vs BB ending, gradually captured pawns and improved its position until the game was adjudicated.
Game 64, Pedone - Texel: Pedone outplayed Texel in a RB vs RB ending. Evals started to increase from move 75, it took 20 moves to capture a pawn, the game lasted until move 119 after Pedone captured another pawn.
Game 81, RubiChess - Minic: In a queen ending Minic captured a pawn and then reduced to a winning king and pawns ending.
Game 86, Winter - DefenChess: The game reached a drawish-looking RB vs RN position, then DefenChess found a winning path that Winter overlooked, reducing to a rook ending two pawns up.
Game 93, Vajolet - Fire: Fire was better in a RR vs BNN imbalance which turned into a QR vs QBN position. Fire went two pawns up and exchanged queens, enough for a win.
Game 102, PeSTO - Nemorino: Nemorino doubled rooks on the h file and PeSTO kept the file closed while playing on the queen side. PeSTO trapped the black king and then opened the h file for a knight. Nemorino's attack was weak while PeSTO's back-rank threat was enough to win material and the game.
Game 109, Pedone - Winter: Winter's king side rook was trapped and Pedone had a strong knight on the 6th rank. Winter freed its rook while Pedone created an advanced queen side passer. Winter gave 3 pawns to get a passer to the 2nd rank, Pedone traded passers and the remaining pieces to get a winning king and pawns ending.
Game 110, Texel - Fire: Texel gave a bishop and attacked the black king, driving it to the queen side and capturing 3 pawns. Fire stabilized the position and pushed a passer to the 2nd rank, together with the extra piece this was enough to win.