Recent question:

> http://chess.stackexchange.com/questions/17192/how-are-the-scores-decided-in-chess

It has been argued that PV scores for Stockfish (the engine being used by chess.com) can be interpreted as something like:

> +1.0 is a pawn advantage for White. -0.5 is a half-pawn advantage for Black. 

**Is that correct?** The weights and parameters in Stockfish are either manually calibrated or tuned by something like the [SPSA optimiser][1]. We only care if the optimization can give the engine gradients to a local optimum solution.

The objective function is to maximise the playing strength. Maximising playing strength has nothing to do with making sure "+1.0 is a pawn advantage for White". In fact, we should be able to **scale** all all the PV scores by a constant. As long as the engine makes the same move, the **magnitude** of the scores shouldn't matter.

This is consistent to the minimax algorithm, where both players **only care** how to minimize/maximise the evaluation. Again, there are **no efforts** to make the PV scores human-interpretable.

To me, the PV scores are only important **relatively**, not **absolutely**. For instance, we should be able to say "+2.0 is about two-times advantage for White than a position with +1.0 for White.", but that **shouldn't** have anything to do with pawns. Similarly, if I modify the source code and scale the outputs by a factor of 10. I can still say: "+20.0 is about two-times advantage for White than a position with +10.0 for White". We **shouldn't** be able to connect the scores to pawns, knights, bishops etc.

I haven't seen anybody in the Stockfish development team spent any efforts to make the outputs interpretable. To me, the scores have no direct interpretation to chess.

Should I call all answers in the question **technically** incorrect?



  [1]: https://chessprogramming.wikispaces.com/SPSA