[gurchik]

Sorry if I misunderstood but it sounds like you're saying engines aren't programmed to make random mistakes in order to lower playing strength, but this is how Stockfish works. Lowering the calculation depth and calculation time is used to reduce difficulty, but in addition to those it is programmed to make mistakes:

> Internally, MultiPV is enabled, and with a certain probability depending on the Skill Level a weaker move will be played.

Within the constraints of the depth and calculation times it determines the best move, but depending on MultiPV it will deliberately not play that move and play an inferior one instead.

[thom]

This still doesn’t mean that engines can’t be made to play weaker moves without making deliberate mistakes, which is the only point I was making.