"Here are the most important details regarding my selection of the 50 opening lines for the TCEC 15 superfinal:
- The selection of this set has been done in the period August-October 2018; it was finalized in November 2018 and hasn't been changed anymore
- All important openings will be played
- The chosen lines typically have a length between 2 moves and 15 moves
- The starting position has returned to the superfinal, it will be line #39
- Average move length is 6.76 (comparable to the 6.68 from the TCEC 14 superfinal)
- There are sharp lines in the set, as well as positional lines, more complex lines, lines with opposite castling ("SALC", i.e. short and long castling), dubious lines and gambits
- Some lines are borrowed from previous superfinals, they can be the same, somewhat shorter, or longer if necessary
- The complexity of a position is one of my main selection criteria, i.e. most pieces are still on the board and there should be a lot of play left, with a reasonable chance for a decisive result
- In each line one side typically has an advantage, so each engine gets the chance to push for a win, while in the return game it has to defend the weaker side
- I have avoided positions that could lead to many exchanges and/or have a high draw rate, as well as positions with symmetrical pawn structures and positions that could lead to easy wins for the side with an advantage
ECO code distribution
ECO A: 15 lines
ECO B: 14 lines
ECO C: 11 lines
ECO D: 3 lines
ECO E: 7 lines
The reason there are less lines selected with ECO codes D and E, is because many lines in these sections are "too easy" for the current top programs and I consider them too drawish. Especially with a very long time control and with strong TCEC hardware.
All lines have undergone a quick check with Stockfish, Komodo and Houdini, which means around 5 minutes on a Ryzen 1700X system (16 threads) for each engine on each position. The sole purpose of this quick check is to make sure:
1) that there are no easy draws available (f.e. 0.00 scores and/or move repetitions)
2) that there will be no mass exchanges
Please note that the quick check cannot predict how the game will continue, or which engine 'likes' the position. The quick check is also not a tool to let engines pick opening lines. The only reason to do this quick check is to avoid quick draws right out of the opening.
The TCEC 14 superfinal saw only 19 wins. This was slightly below my minimum goal of 20 wins. Of course I hope that in the TCEC 15 superfinal we will reach at least this minimum of 20 wins. In any case, remember that in each line anything can happen! Wild lines can turn quickly into liquidations to a drawn ending, more quiet lines can suddenly explode into exciting games. While my selection method is destined to get as many games in the 2nd category, there is surely no guarantee this will happen.
Previous superfinals saw long strings of draws, but also lots of wins in a short period of time. This is normal in long matches between top engines and I am sure we will see this in the TCEC 15 superfinal, too.
Last but not least: have fun!
For me, TCEC is currently the most interesting chess engine tournament around. Once again it was a challenging but interesting job to pick the positions for this superfinal edition. I hope you enjoy the games and we will see lots of exciting chess!"