STS(v11.0) King Activity.010

A continuation of the discussion started here:
jomega's Blog • Strategic Test Suite (STS): The EPD file's best and alternate best moves. • lichess.org

Another interesting position for which Stockfish 14 failed to find the best move in the 3 second (depth 24) test. Stockfish did find one of the alternate best moves.

As a puzzle, this position is interesting because it is not a "Black to play and win.", but instead a puzzle about finding the best defense.

The position belongs to the STS category Activity of the King. According to the web page sites.google.com/site/strategictestsuite/activity-of-the-king, this category covers the following. [The person quoted is Swaminathan Natarajan.]

These tests cover all king movements prior to or after the castling. Idea of this is to test whether it's appropriate to bring the king forward for the battle, or to move the king to a more defensive square. I accepted king moves which were made in late middle game to early endgame. Especially moves where king can be used as
\* an active defender,
\* an aggressive attacker with respect to assisting pawns,
\* a space restrictor,
\* a blockader.

My study on this position is here:

The Human Perspective

Black's backward e-pawn on the half-open e-file is his main issue. His pieces are also cramped. The e-pawn can be defended in several ways, however some of these give Black a very passive position. The intended solution to move the Black King to f7 has a mainline variation that gets rid of the weak e-pawn and increases the scope of his Queen Bishop (or exchanges it). A human would prefer that solution to sitting in a passive position.

Stockfish's Perspective

Stockfish wants to pick either 1...Re8 or 1...Nd8 because both of those evaluate to 0.0 while 1...Ke7 evaluates as a minuscule plus for White. At the end of the mainline variation for 1...Ke7, in the study, Stockfish calculates the score as 0.18/30. This is always the Stockfish perspective - pick the move that gives the best score. Getting Stockfish to chose 1...Ke7 would be difficult because Stockfish has no concept that sitting in a passive position can be a 'bad idea'. It is not always a 'bad idea'; so how would you differentiate the cases?

EPD Changes Needed

None.

Links

\- The Strategic Test Suite \(STS\) home page\.
https://sites.google.com/site/strategictestsuite/
\- The STS\-rating code\.
https://github.com/fsmosca/STS-Rating