user25328: Firstly, I am not suggesting that there is anything wrong the way engines are implemented at the moment, by analyzing only the current position regardless of time left by the players. This is great and it gives us a nearly perfect estimation of the position.
To the best of my knowledge, current engines do not take into account the time left by the players in a game when analyzing a position.
When I am watching an online transmission of a chess championship match, when the players get low on time it is very common for commentators to state "Ohh, I don't think <player> will find this move with only 10 seconds on the clock!", when there's only one move in the position that it is really hard to find (hence would require more thinking time that they do not have). Maybe I am on the minority here, but I think it would be interesting to have a separate evaluation by an engine that takes into account the time left.

My questions are: Is there such an evaluation out there? Are there any downsides when taking into account time or something that makes this calculation impossible to do?

user33645: Position evaluation by an engine is completely objective.  Put any 2 players in a given position and the eval is the same.  Once you add the clock into the equation the evaluation becomes different depending on who the player is.  The objective evaluation becomes a subjective evaluation which no longer has any concrete meaning.

user12873: Stockfish has 'wtime' and 'btime' options, that get it to calculate as if white and black only have such and such time left. However, in cases you're mentioning where human players only have a few seconds to find a move, even here Stockfish would most likely find the move under these wtime & btime constraints.

user15223: This is an exposition of BlueRaja - Danny Pflughoeft's answer, which is correct. Given the option between making 1) the objectively strongest move and 2) the one against which the best move is "really hard to find", would you really rather an engine make move #2?
Let's say you make move #2. If opponent doesn't find it, congrats, you win. If opponent does - then what? Did you just throw away your winning chances? Did you just go from losing to lost? If the answer to either of the above is "yes", not only should an engine not make that move, a human should not make that move either!
Example:
[FEN "3r2k1/2pqnpp1/1p5p/p2P4/P2p1rP1/2P1N3/1PQ2PP1/3RR1K1 w - - 0 1"]

1. g3 dxe3 2. gxf4 Qxg4+

This position is from Nepomniatchi-Carlsen, World Chess Championship 2021. It is dead equal - 0.00 eval according to Stockfish. Stockfish's main line begins with 1. Rxd4 and leads to a draw. However, Nepo played 1. g3. Now when a piece comes under attack, the first inclination is to move it. Accordingly, the first move Carlsen is likely to look at is 1...Rf6. Look a bit further though, and Black will notice that 1...dxe3 wins (since 2. gxf4? Qxg4+ followed by a rook lift is a decisive attack).
Would you really rather an engine play 1. g3 instead of 1. Rxd4? Phrased alternatively, would you rather get a sure draw, or a "maybe" win that is a guaranteed loss if opponent sees the key move? Think about it. Nobody - engine or human - should prefer the latter.
That said: engines do have a measure of how complex the current position is. If the engine believes it is stronger than its opponent, then it will try to steer the game towards more complex positions. Inferior opposition is more likely to blunder in those positions. That's how engines exploit their opponents.

user12629: I imagine someone could go through a bunch of GM games that have time information included and do some sort of statistical analysis to correlate time with win probability for a given evaluation. It could never be perfect, but neither are traditional engine evaluations or ratings or anything else you'd use to predict the outcome of a game.
But to make it reasonably accurate you'd also have to account for things like player strengths and material left on the board and known-drawn positions (a 0.0 evaluation coming out of a nonstandard opening and a 0.0 evaluation in an opposite-colored-bishops endgame with one pawn on each side are very different when it comes to win probability.) You'd probably want to check whether there's one narrow path to victory or multiple moves which could all do the job. You might also have to account for things like whether it's OTB or online; 10 seconds left to convert a won position when you have to physically hit a clock is way different from when you can use a mouse and can premove.
It's mostly a question of whether someone is willing to put forth the effort to do all of this. Exactly how badly do we want to know the odds of one imperfect human beating another in a given situation?

user52: Because engines find the best move by assuming best play, not by hoping their opponent makes an inferior move.
If you constructed an engine whose sole purpose was to beat a specific person/engine, then "likelihood to play a given bad move" could make sense as an evaluation parameter.  But otherwise it's a waste of time to calculate something that would ultimately lead to the engine playing weaker moves.

user4418: 
Why don't chess engines take into account the time left by each player?

For the simple reason that there is no way of knowing how to do that.
A few years ago a clubmate rated about 1800 playing in the British Universities blitz (3+2) championships reached a KNB v K endgame. He knew the endgame and so blitzed out the win. I have other clubmates rated 2100+ who don't know that endgame and would not be able to checkmate in such period of time. Give them 20 minutes on the clock and they still might not succeed. There have been cases of IMs failing to do this at regular time controls.
In short it is an impossible task.

25328: <p>Firstly, I am not suggesting that there is anything wrong the way engines are implemented at the moment, by analyzing only the current position regardless of time left by the players. This is great and it gives us a nearly perfect estimation of the position.</p>
<p>To the best of my knowledge, current engines do not take into account the time left by the players in a game when analyzing a position.</p>
<p>When I am watching an online transmission of a chess championship match, when the players get low on time it is very common for commentators to state &quot;Ohh, I don't think &lt;player&gt; will find this move with only 10 seconds on the clock!&quot;, when there's only one move in the position that it is really hard to find (hence would require more thinking time that they do not have). Maybe I am on the minority here, but I think it would be interesting to have a separate evaluation by an engine that takes into account the time left.</p>
<hr />
<p>My questions are: Is there such an evaluation out there? Are there any downsides when taking into account time or something that makes this calculation impossible to do?</p>
 33645: <p>Position evaluation by an engine is completely objective.  Put any 2 players in a given position and the eval is the same.  Once you add the clock into the equation the evaluation becomes different depending on who the player is.  The objective evaluation becomes a subjective evaluation which no longer has any concrete meaning.</p>
 12873: <p>Stockfish has 'wtime' and 'btime' options, that get it to calculate as if white and black only have such and such time left. However, in cases you're mentioning where human players only have a few seconds to find a move, even here Stockfish would most likely find the move under these wtime &amp; btime constraints.</p>
 15223: <p>This is an exposition of BlueRaja - Danny Pflughoeft's answer, which is correct. Given the option between making 1) the objectively strongest move and 2) the one against which the best move is &quot;really hard to find&quot;, would you really rather an engine make move #2?</p>
<p>Let's say you make move #2. If opponent doesn't find it, congrats, you win. If opponent does - then what? Did you just throw away your winning chances? Did you just go from losing to lost? If the answer to either of the above is &quot;yes&quot;, not only should an engine not make that move, a human should not make that move either!</p>
<p>Example:</p>
<pre><code>[FEN &quot;3r2k1/2pqnpp1/1p5p/p2P4/P2p1rP1/2P1N3/1PQ2PP1/3RR1K1 w - - 0 1&quot;]

1. g3 dxe3 2. gxf4 Qxg4+
</code></pre>
<p>This position is from Nepomniatchi-Carlsen, World Chess Championship 2021. It is dead equal - 0.00 eval according to Stockfish. Stockfish's main line begins with 1. Rxd4 and leads to a draw. However, Nepo played 1. g3. Now when a piece comes under attack, the first inclination is to move it. Accordingly, the first move Carlsen is likely to look at is 1...Rf6. Look a bit further though, and Black will notice that 1...dxe3 wins (since 2. gxf4? Qxg4+ followed by a rook lift is a decisive attack).</p>
<p><strong>Would you really rather an engine play 1. g3 instead of 1. Rxd4?</strong> Phrased alternatively, would you rather get a sure draw, or a &quot;maybe&quot; win that is a guaranteed loss if opponent sees the key move? Think about it. Nobody - engine or human - should prefer the latter.</p>
<p>That said: engines do have a measure of how complex the current position is. If the engine believes it is stronger than its opponent, then it will try to steer the game towards more complex positions. Inferior opposition is more likely to blunder in those positions. That's how engines exploit their opponents.</p>
 12629: <p>I imagine someone could go through a bunch of GM games that have time information included and do some sort of statistical analysis to correlate time with win probability for a given evaluation. It could never be perfect, but neither are traditional engine evaluations or ratings or anything else you'd use to predict the outcome of a game.</p>
<p>But to make it reasonably accurate you'd also have to account for things like player strengths and material left on the board and known-drawn positions (a 0.0 evaluation coming out of a nonstandard opening and a 0.0 evaluation in an opposite-colored-bishops endgame with one pawn on each side are very different when it comes to win probability.) You'd probably want to check whether there's one narrow path to victory or multiple moves which could all do the job. You might also have to account for things like whether it's OTB or online; 10 seconds left to convert a won position when you have to physically hit a clock is way different from when you can use a mouse and can premove.</p>
<p>It's mostly a question of whether someone is willing to put forth the effort to do all of this. Exactly how badly do we want to know the odds of one imperfect human beating another in a given situation?</p>
 52: <p>Because engines find the best move by assuming best play, not by hoping their opponent makes an inferior move.</p>
<p>If you constructed an engine whose sole purpose was to beat a specific person/engine, then &quot;likelihood to play a given bad move&quot; could make sense as an evaluation parameter.  But otherwise it's a waste of time to calculate something that would ultimately lead to the engine playing weaker moves.</p>
 4418: <blockquote>
<p>Why don't chess engines take into account the time left by each player?</p>
</blockquote>
<p>For the simple reason that there is no way of knowing how to do that.</p>
<p>A few years ago a clubmate rated about 1800 playing in the British Universities blitz (3+2) championships reached a KNB v K endgame. He knew the endgame and so blitzed out the win. I have other clubmates rated 2100+ who don't know that endgame and would not be able to checkmate in such period of time. Give them 20 minutes on the clock and they still might not succeed. There have been cases of IMs failing to do this at regular time controls.</p>
<p>In short it is an impossible task.</p>
