Season 22 league 4

Final standings

Berserk, Weiss, Bit-Genie and Drofa advance to league 3. Berserk had an remarkable first RR with 10 wins and a draw, it was obviously the best engine in the league. Weiss was second at the half point and kept its position with a good +9 score. Bit-Genie, Drofa and Chiron fought to get in the top 4. Bit-Genie finished 3rd after beating the other two engines in their head to head matches. Drofa and Chiron were close until the end, Drofa had an unexpected loss to Amoeba but Chiron missed its opportunity to catch up and Drofa qualified in the final round.

Berserk and Bit-Genie advance for the second time this season. Judging by Berserk's scores it appears league 4 was weaker than the qualification league, but keep in mind that there were no opening books in the qualification league so it is difficult to compare. The other two qualifiers, Chiron and Zahak, stop in league 4. 

The 4 qualifiers will join the following 8 engines in league 3:
played in season 21 league 2 - Seer, Arasan
played in season 21 league 3 - Wasp, Tucano, Koivisto, Marvin, pirarucu, Topple

There are only two qualifiers in league 3 and it is going to be tougher. In the swiss event Koivisto and Arasan were close to Berserk, Weiss and Drofa were close behind. It is unknown how they compare to Bit-Genie.

Interesting games

game 10, Chiron - Stash: Evals were close to 0, Stash had a strong passer yet its queen was almost trapped. The black king moved to the center, Stash was surprised by a pawn sacrifice by Chiron that was followed by an attack on the king, with evals jumping. Most pieces were exchanged and the game reached a queen ending. The queens were exchanged, both engines queened again but Chiron was first and the black king was exposed. This was enough to get a two pawn lead and win.

game 12, Weiss - Monolith: Monolith gave a rook for a bishop early, it thought that the exposed white king in the center compensated for the material. Weiss gradually exchanged pieces, its king was not threatened and it castled eventually. The game reached a R vs N ending and Weiss had enough pawns to win.

game 20, Berserk - MrBob: The game reached a RRB vs RRN position, Berserk had an eval advantage but evals did not change for a long time. On move 68 MrBob deserted the back rank and a white rook immediately took over. After exchanging rooks the white king came forward, the black pieces were too far to help. Material was equal but Berserk used the threat on the black king to promote a passer and win.

game 31, Zahak - Berserk: The game reached a BNN vs RBN position, white was two pawns up with 3 connected passers on the queen side. Zahak started to push a passer forward but (negative) evals increased. Berserk reduced to a N vs R ending, the white passer was unprotected too far ahead and was captured. The last black pawn became a passer on the king side, Zahak lost its knight to stop it giving Berserk the win.

game 41, Drofa - Bit-Genie: The game reached a RR vs RB position, black a pawn up with two connected passers. Drofa was not accurate enough, Bit-Genie was able to push its passers safely forward. Drofa lost a rook for one passer, Bit-Genie queened the other passer to win.

game 42, Berserk - Chiron: Evals slowly increased in a closed position with only a few exchanges. On move 43 Chiron gave a rook for a bishop to keep the queen side closed. After a while Berserk opened the king side and reduced to a RR vs RN position. The white rooks were strong, Berserk went 3 pawns up to win. 

game 44, Bit-Genie - Berserk: Berserk opened the center with a rook sacrifice. The white king was exposed, Berserk had a strong knight on d3, and the white pieces were misplaced, balancing the material advantage that Bit-Genie had. However, Bit-Genie was not careful enough, Berserk (negative) evals jumped and it created connected passers. Bit-Genie lost material to stop the passers, the game reached an opposite color bishops ending with Berserk two pawns up. The black king managed to protect its pawns, the remaining white pawns were vulnerable. The game ended in a tablebase win for Berserk.

game 52, Drofa - Monolith: The position was closed with almost all pawns on the board, evals started to increase after move 43. The position opened up and the engines exchanged pieces until only QN vs QN remained, material was equal but Drofa had a queen side passer. Monolith could not block the passer, eventually Monolith queened and won.

game 53, Berserk - Weiss: The game reached a QBN vs QR position on move 43 after both engines queened a pawn. Berserk had a queen side passer that slowly moved forward, Weiss blocked with its rook when the passer was on the 7th rank. Weiss had passers on the king side that slowly moved forward, somehow Berserk found the right moves to stop the passers and eventually force the black rook to move. The game reached a 7-man QBN vs QP position, a win for white.

game 55, Zahak - Bit-Genie: Zahak had a small eval advantage after the start, evals turned negative after Zahak missed a strong attack by the black pieces on the long diagonal. Many exchanges followed and when the dust cleared only BB vs RB remained. It was a long endgame, Zahak defended with its bishops, but after almost 40 moves Bit-Genie captured a bishop and then mated.

game 66, Bit-Genie - Weiss: Weiss was a pawn up early, Bit-Genie tried to threaten the black king on the queen side but nothing came out of it. Evals turned negative though Bit-Genie regained the pawn. Weiss gave a bisיop and attacked the white king, it regained the material and the game reached a QRB vs QRB position. Weiss used the exposed white king to eventually reduce to a winning queen ending two pawns up.

Standings after RR1: Berserk +10, Weiss +4, Drofa +3, Bit-Genie +2, Chiron +1,  Zahak MrBob -1, Monolith Stash -2, Cheng -3, Amoeba -5, Nirvana -6. Berserk with a remarkable score of 10.5/11, no doubt it will finish first. The 3 remaining spots for advancing are more contested, the 4 engines with a positive score are the probable candidates. Amoeba and Nirvana are at the bottom with no wins and losing half of their games.

game 67, Zahak - Weiss: There were almost no exchanges, evals were close to 0 and the first piece exchange was on move 42. On move 49 Zahak missed Weiss' move, and it lost a knight for 2 pawns. Weiss attacked the white king and gained material, mate came quickly.

game 88, Cheng - Bit-Genie: Bit-Genie didn't see its king was in danger, evals jumped as Cheng attacked on the king side. The center was blocked and most of the black pieces were too far to help. After some preparation Cheng reduced to a Q vs R ending and won. 

game 96, Berserk - Drofa: Drofa moved its queen to the queen side, Berserk saw an opportunity to attack the king side. Drofa exchanged pieces but still Berserk was a pawn up in a RRB vs RRN position. Eventually Berserk reduced ro a rook ending and captured a second pawn to win. 

Standings with 6 rounds to go: Berserk +13, Weiss +7, Drofa Bit-Genie +3, Chiron +2,  Zahak 0, MrBob -1, Monolith -2, Stash -3, Cheng -5, Amoeba -8, Nirvana -9. Berserk and Weiss will qualify, the race for 4th place is very close between Drofa, Bit-Genie and Chiron. Bit-Genie was hit by its unexpected loss to Cheng. 

game 97, Berserk - Zahak: Zahak was up a pawn early, but it had a trapped bishop on the queen side and its king side rook could not develop. Berserk regained the pawn and the game reached a RBB vs RBN position. Berserk forced a bishop for knight exchange, removing the only effective black piece. The engines reduced to a rook ending, Berserk went 4 pawns up to win. 

game 99, MrBob - Bit-Genie: MrBob crashed on the opening move, giving Bit-Genie a free point. 

game 110, Berserk - Bit-Genie: The black queen was on the queen side from the start. After blocking the center Berserk waited for the right moment to open the king side. It went a pawn up, created a passer and captured a bishop. Bit-Genie countered by attacking the white king with its queen, but it was too weak and too late. Berserk exchanged queens and created a second passer, mate followed.

Race for 4th place with 3 rounds to go: Drofa Bit-Genie +3, Chiron +2. No change in the scores. The direct matches between Drofa and both Chiron and Bit-Genie were draws. Chiron held against Berserk, Drofa held against Weiss, Bit-Genie lost to Berserk and got a free point from a crash against MrBob.  Drofa has the easiest remaining games so its chances are greatest to qualify. The direct match between Bit-Genie and Chiron may decide their final standings, if the game is not drawn.

game 118, Monolith - Drofa: Drofa had a promising eval advantage in a QRB vs QRB position, it allowed a queen exchange at the wrong time and allowed Monolith to hold. Drofa ended the game in a KBP vs K ending, not realizing this was a draw with a flank pawn and the wrong colored bishop.

game 120, Bit-Genie - Chiron: Evals increased as the engines played mostly behind their pawn lines. Chiron had a bishop that was very passive and almost trapped, after exchanging all rooks Bit-Genie went 2 pawns up and reduced to a N vs B ending. The black bishop found space but it had no targets. Bit-Genie queened a pawn and won.

In round 20 Bit-Genie beat Chiron, Bit-Genie moves to 3rd place while Chiron is probably out of the race. Drofa only managed a draw against Monolith and it is in 4th place. Standings with 2 rounds to go: Bit-Genie +4, Drofa +3, Chiron +1. 

game 121, Bit-Genie - Zahak: There were no exchanges until move 20, the engines castled in opposite directions. Evals increased as Bit-Genie went a pawn up and opened the king side. The engines reduced to a QRB vs QRB position and Bit-Genie captured a second pawn. After exchanging queens the white passers secured a win for Bit-Genie.

game 124, Drofa - Amoeba: Amoeba castled long after the g file opened, the black king was much safer than the white king. Drofa pushed a pawn to a6 and tried to attack on the queen side, it was not careful enough while Amoeba doubled rooks on the g file. Amoeba used a mating threat to capture two pawns, then reduced to a rook ending. The game ended in a tablebase win.

In round 21 Bit-Genie secured 3rd place with a win. Drofa lost to Amoeba (!) while Chiron held against Weiss, Chiron is only 0.5 points behind in the race for 4th place. Standings before the last round: Bit-Genie +5, Drofa +2, Chiron +1. 

In the last round Drofa only managed a draw against Stash. Chiron still could tie the score but its last game against Monolith was a draw, Drofa finishes in 4th place.