Currently, we do not consider pawns passed if there is another pawn of
the same color in front of them. It appears that this condition is not
necessary. The idea is that the doubled pawns are likely to be weak and
one of them will be likely captured anyway. On the other hand, if we do
somehow manage to promote a pawn, then the pawn behind it becomes passed
as well. In any case, the end result is we end up with an extra
potentially passed pawn. The current evaluation for passed pawns already
handles this case by also scaling down this effect.
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 28291 W: 6287 L: 6178 D: 15826
http://tests.stockfishchess.org/tests/view/5b6c4b960ebc5902bdb9f256
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 30717 W: 5256 L: 5151 D: 20310
http://tests.stockfishchess.org/tests/view/5b6c82980ebc5902bdb9f863
Bench: 4938285
This tweak excludes files D and E from the KingFlank bitboard when our
king is on the A or H files respectively. As far as I can tell, this
affects two things: the calculation for CloseEnemies and PawnlessFlank.
Aside from filtering out slightly less relevant attacks in the flank,
I suspect this helps with king prophylaxis, avoiding attacks and moving
towards the center when the pawns start to come off.
STC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 56755 W: 12881 L: 12489 D: 31385
http://tests.stockfishchess.org/tests/view/5b58a94c0ebc5902bdb88c72
LTC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 130205 W: 22536 L: 21957 D: 85712
http://tests.stockfishchess.org/tests/view/5b58b7580ebc5902bdb89029
How to continue: Tweaking the two bonuses mentioned might give some
gain, although as far as I can tell, CloseEnemies is very sensitive to
even small changes.
Closes https://github.com/official-stockfish/Stockfish/pull/1705
Bench: 5026009
There seems to be some strange interaction between Overload and Connectivity.
Overload encourages us to not have too many defended and attacked pieces,
as this may expose us to various tactics. This feels somewhat like it is in
conflict with Connectivity, where pieces are defended preemptively.
Here I take the "pick one or the other" approach and just remove connectivity,
while strengthening the effect of Overload to compensate. The reasoning is that
if we defend our pieces preemptively, then it does get attacked, we want to do
something about it so we don't get penalized by Overload. On the other
hand, if it doesn't get attacked, then there's no need to defend it.
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 27734 W: 6174 L: 6064 D: 15496
http://tests.stockfishchess.org/tests/view/5b5073bd0ebc5902bdb7ba5c
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 51606 W: 8897 L: 8827 D: 33882
http://tests.stockfishchess.org/tests/view/5b50aa900ebc5902bdb7bf29
Bench: 4658006
After some recent big tuning session, the values for King Protector were
simplified to only be used on minor pieces. This patch tries to further
simplify by just using a single value, since current S(6,5) and S(5,6)
are close to each other. The value S(6,6) ended up passing, although
S(5,5) was also tried and failed STC.
STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 14261 W: 3288 L: 3151 D: 7822
http://tests.stockfishchess.org/tests/view/5b4ccdf50ebc5902bdb77f65
LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 19606 W: 3396 L: 3273 D: 12937
http://tests.stockfishchess.org/tests/view/5b4ce4280ebc5902bdb7803b
Bench: 5448998
