Season 20 league 2

Final standings

Nemorino and Defenchess advance to league 1, Wasp and Minic are relegated to league 3.

The league was more or less divided into two sections, the top 6 engines had a chance of qualifying and the bottom 4 engines tried to avoid relegation. Both races were close and were decided only in the last few rounds. In the end tiebreaks were needed in both races. Both pairs of tied engines, Defenchess/Vajolet and Seer/Minic, drew their direct encounters. Therefore r-mobility was used as a the second tiebreak.

The tiebreak decision for Defenchess was interesting and a little disturbing. In game 50 Defenchess played Arasan and the game reached a 7-man drawn bishop vs pawns position. Both engines had high evals and played on until a 50-move draw. When Arasan saw the draw is unavoidable it played random moves, and the final position was a win for white if you ignore the 50-move rule. As it is the r-mobility uses 7-man tables to adjudicate and ignores the 50-move rule in tablebase positions, therefore Defenchess was granted an r-mobility win for this draw. This unusual score was enough for Defenchess to beat Vajolet in the tiebreak decision, according to my calculations Vajolet would have advanced otherwise.

The two qualifiers join the following engines in league 1, which will be an 8-engine 2DRR event:
relegated from premier division season 19: Ethereal (Fire does not play in this season)
played in league 1 season 19: Slowchess, Xiphos, RubiChess, rofChade, Igel

Interesting games

Game 6, Fritz - Defenchess: Fritz pushed the h pawn forward on the open h file facing the black king. Defenchess let the pawn reach the 7th rank but kept the king side closed and its king safe. Meanwhile Defenchess captured a pawn and had a pawn majority on the queen side. After many exchanges the game reached a RB vs RB ending, Defenchess had a an unstoppable passer that ensured the win.

Game 10: Pedone - Vajolet: There were almost no exchanges after the start and the engines seemed to be shuffling, then Pedone sacrificed a bishop and attacked on the king side. Most of the black pieces were stranded on the queen side and Vajolet's king was soon in a mating net. 

Game 17, Seer - Defenchess: Seer gave two pawns and attacked the uncastled black king. Defenchess had to give material to stop an advanced passer, the game reduced to a QB vs RBN position. Evals were high but Seer couldn't find a win. It started shuffling in a Q vs R ending, draw after 50 moves.

Game 23, Arasan - Pedone: Arasan captured a bishop for pawns early in the game. Arasan arranged its pieces and then opened the king side. The attack on the black king was deadly, Pedone had to lose material, this led to a Q vs N ending and a win for Arasan.

Game 24, Defenchess - Winter: Winter gave a pawn and created an advanced passer on the queen side. Defenchess blocked the passer, opened the king side and attacked the black king. Defenchess won some material and reduced to a R vs B ending, getting back in time to stop the passer. The game ended in a tablebase win for white.

Game 27, Winter - Nemorino: Winter was up a rook for 3 pawns while Nemorino had a passer on the 2nd rank. Winter may have missed a win due to lack of tablebase support, the game reduced to a tablebase draw with both engines about to queen a pawn.

Game 28, Pedone - Defenchess: Pedone gave a pawn early and created a hole in the pawn wall on the queen side. Much later the white queen advanced through this hole supported by knights, while the white rooks pressed on the king side. Pedone attacked patiently from both sides, by move 90 most of the pawns were gone. Defenchess was forced to trade its queen for a rook to avoid mate, the game was over 15 moves later.

Game 38, Vajolet - Nemorino: Nemorino created a passer on the queen side, then slowly exchanged pieces and pushed the passer forward. Vajolet lost a few pawns while preventing the passer from advancing, The game reached a RB vs RN position with black 3 pawns up, enough for a win. 

Game 45, Winter - Pedone: Winter gave material for a strong attack on the black king. After many exchanges the attack was over in a RBN vs RN position. Pedone was two pawns up, but Winter used the still vulnerable black king to capture the knight and win.

Scores after 9 rounds:  Nemorino +3, Pedone Vajolet +2, Defenchess Winter +1, Fritz +0, Seer Minic Arasan -2, Wasp -3. Races are very tight at the top and at the bottom. In general the engines with positive scores performed well against engines with negative scores, so this divide will probably continue to hold.

Game 46, Fritz - Pedone: Pedone tried to attack on the queen side without success, the game reached a RN vs RB position. Fritz captured a pawn and had connected passers on the king side, while Pedone had a passer on the queen side. Fritz gave its rook to stop the black passer, but Pedone could not stop a white promotion. Pedone lost its rook to prevent a second queening, game over.

Game 49, Nemorino - Minic: Minic seemed to have an advantage in a QBB vs QRN position with both evals over (negative) 3. However it chose to reduce to a drawn queen ending with a pawn up.

Game 52, Arasan - Nemorino: Arasan doubled rooks on the open g file with the black king in the corner on move 19. Not a lot happened and it seemed that Nemorino would hold, even after it gave a rook for a bishop and pawn. The position opened up, Arasan walked its king to safety. Only after move 85 Arasan's threats became effective and it reduced to a winning Q vs R ending.

Game 55, Vajolet - Pedone: Pedone opened the king side and attacked the white king. Vajolet stopped the attack and the game reached a RB vs RB position, Pedone with a pawn up and an advanced passer. Vajolet had to block the passer, Pedone used its rook to capture another pawn and create a second passer, enough for a win.

Game 60, Nemorino - Defenchess: Nemorino had a passer on the queen side, it gave a rook for a bishop and pushed the passer to the 7th rank. Defenchess couldn't get rid of the passer, Eventually it lost a rook for it. The material advantage gave Nemorino the win.

Game 64, Minic - Pedone: Minic was up a rook for a knight early in the game. Minic created a passer on the king side , then after some shuffling reduced to a RR vs RN position. Minic used its strong rooks to slowly capture all the black pawns, Pedone lost its rook for a second passer and mate followed soon. 

Game 69, Winter - Defenchess: Defenchess opened the king side, then gave its queen for a knight. The white king was in danger and Winter gave material back, the attack ended with Defenchess up a piece. The black rooks and bishops were strong on the open board, Defenchess gained more material and was up a rook before tablebase adjudication.

Game 73, Defenchess - Pedone: Pedone made the wrong move and found its king under attack with all its major pieces too far away. One black rook could not return on time and Pedone gave it for a bishop. Defenchess reduced to a winning R vs B ending.

Scores after 15 rounds: Nemorino +5, Vajolet +4, Defenchess +2, Pedone Winter Fritz +1, Arasan -2, Minic -3, Seer -4, Wasp -5. Nemorino and Vajolet opened a small gap at the top, though nothing is decided yet at the top or at the bottom of the table. Only 3 rounds to go.

All draws in round 16, no change in the scores and only 2 rounds left. Nemorino is close to qualification and Arasan is close to being safe.

Game 81, Winter - Fritz: Winter sacrificed a knight for pawns and opened the position. The game reached a RB vs RBN position. Winter had 3 connected passers in the center and Fritz lost a piece for each passer, game over.

Game 83, Nemorino - Vajolet: Nemorino gave a rook for a bishop and pawn and exposed the black king. After many exchanges the game reached a RBN vs RN position, black 2 pawns up. It took Nemorino another 30 moves of slow improvement to win.

Scores after 17 rounds: Nemorino +6, Vajolet Defenchess +3, Winter +2, Pedone +1, Fritz +0, Arasan -1, Minic Seer -4, Wasp -6. Nemorino is sure to qualify, the last round will determine 2nd place. Same goes for the two engines to be relegated. The top 3 and bottom 3 engines play each other in the last round, even draws could be important.

Game 90, Pedone - Winter: Winter's development was slow and its king moved without castling. Pedone attacked quickly, it opened the center and exposed the black king. Winter gave material but that only delayed the mate.

Nemorino, Vajolet and Defenchess beat Wasp, Seer and Minic respectively. Nemorino qualifies and Wasp is relegated, there are ties between Vajolet and Defenchess and between Minic and Seer. In both cases the head-to-head scores are also tied, so r-mobility is used. As a result Defenchess is the second qualifier and Minic is the second engine relegated.