[mlyle]

> in fact if you plug it into an engine, it shows an equal evaluation

I don't think this is true, and engine evals aren't everything.

Two positions can have equal evaluations, but one can be trivial to play optimally and the other can be tricky and have a 10 move long sequence of "only moves" that are really hard to calculate. The latter is a much worse move, if you are not a chess engine.

[billforsternz]

Your last paragraph is the nicest capsule description of this very important and yet widely misunderstood computer chess concept I've seen. Thanks! I'm going to use this (probably poorly paraphrased due to my failing memory:).

[h3half]

I've often seen this described as the "sharpness" of a position

[janalsncm]

That’s reasonable, but the question we really want to know is how difficult it will be to equalize, which is a measure of both the number of equalizing moves and how difficult it is to find them. If the only moves are obvious, it’s not as bad as you might originally think.

In other words the correct calculation of subjective difficulty is a dot product, not simply a count of the number of equalizing moves.

[mlyle]

Yah, I'm not saying that a way to figure out the "difficulty of position" is to simply count the number of "only moves" or a volatility measure. There's sometimes a sequence of obvious trades to make, and that's hardly a difficult position.

It's hard to capture "obvious". One metric is how far you need to look down the eval tree to know a move is good, but even that is flawed.

[janalsncm]

Yes, it would be hard to avoid stepping into the scope of psychology to truly answer the question, because what might be easy for you might not be for me, even if we had equal elo ratings. (Trivial example, we might have equal elos but I try out a new opening you normally play.) You can probably learn a function to give a reasonable estimate though.

[mlyle]

I prefer something kind of objective rather than looking at player strengths. The "depth needed to search to pick equal move" is my best answer, maybe revised to be "and isn't found with a couple of simple heuristics" to clean it up some.

[sa46]

Is there a chess metric that combines centipawns with a complexity metric?

[fsckboy]

you are replying to a comment that says "he miscalculated an equal position further down the line" and your point of objection is that he miscalculated an equal position further down the line?

still your move

[mlyle]

You've not understood what is said.

If on move 29, you choose a move that is slightly worse but leave yourself in an extremely difficult position for you but an easy one for the other guy...

And then only on move 40 does the eval extremely diverge...

In my opinion, your real blunder was on move 29, not 40. Just because an engine could hold a position doesn't make it a reasonable move.

[fsckboy]

but that says nothing about what Fisher was thinking, so while your opinion is valid, it's not more valid than the comment you replied to, especially when your comment mimics the structure of his comment in the way I pointed out.

[mlyle]

Fisher had said that he was seeking to complicate the game-- which is something that black wants to do, in general-- add uncertainty for both sides.

In practice, the move only added uncertainty for black. White faced easy choices, and black difficult ones.

I didn't disagree that Fisher thought the move was safe and miscalculated. Indeed, he didn't even miscalculate badly-- engines think they can hold the position.

I'm asserting that the move fails because it made the subsequent game more complicated for Fisher without imposing an equal penalty on his opponent. It made a bad miscalculation almost inevitable.

[dmurray]

> Fisher had said that he was seeking to complicate the game-- which is something that black wants to do, in general-- add uncertainty for both sides.

This is not something Black wants to do in matchplay chess in general. Usually he would be happy with a sterile draw and hope to take advantage of having an extra white in the remaining games.

Fischer, on the other hand, liked to play for a win in every game. And IIRC this match gave the defending champion draw odds, so the challenger had more incentive than normal to take risks, even in game 1.

Still, I generally agree with the analysis of Kasparov etc in this position. Fischer didn't miss the game continuation and he didn't assess the piece-down position as offering Black his share of winning chances. He more likely missed that after Bxh2 g3 h5 Ke2 h4 Kf3 h3 Kg4 Bg1 Kxh3 Bxf2 Bd2! White still traps the bishop.