From: protonspring <mike@whiteley.org>
Date: Tue, 31 Mar 2020 21:08:55 +0000 (-0600)
Subject: remove KNPK endgame code
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=3cb1c6c3c6206c3c2a0d78ce1cb9820256efc96e;hp=3cb1c6c3c6206c3c2a0d78ce1cb9820256efc96e

remove KNPK endgame code

In more than 100k local KNPK games, there is no discernible difference between master and master with this endgame removed: master:42971, patch:42973, draws: 3969. Removal does not seem to regress in normal games.

STC
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 46390 W: 8998 L: 8884 D: 28508
Ptnml(0-2): 707, 5274, 11163, 5300, 751
https://tests.stockfishchess.org/tests/view/5e83b18ee42a5c3b3ca2ef02

LTC
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 44768 W: 5863 L: 5814 D: 33091
Ptnml(0-2): 251, 3918, 14028, 3905, 282
https://tests.stockfishchess.org/tests/view/5e84a82a4411759d9d0984f4

In tests with a book of endgames that can convert into KNPK, no significant difference can be seen either

```
TC 1.0+0.01
Score of patch vs master: 6131 - 6188 - 27681  [0.499] 40000
Elo difference: -0.5 +/- 1.9, LOS: 30.4 %, DrawRatio: 69.2 %

TC 2.0+0.02
Score of patch vs master: 5740 - 5741 - 28519 [0.500] 40000
Elo difference: -0.0 +/- 1.8, LOS: 49.6 %, DrawRatio: 71.3 %
``

closes https://github.com/official-stockfish/Stockfish/pull/2611

Bench 4512059
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