Note 0.1: see this meta post.
Note 0.2: In re the answer, not sure if the following is relevant, but: I'm not a n00b. I'm just a bad player. Haven't played in awhile, so I'm just reviewing/revising the stuff. In fact, I think it's my non-n00bish ness that enables me to question Josh Waitzkin's claims. As it turns out, some of my answers are better or equal to Josh's. See here and here. I'm not saying I deserve praise for the effort of thinking, looking it up and even typing up the results of the engine here. I just really don't think I should've gotten unsolicited advice about using an engine. Again, see this meta post.
Taken from: Josh Waitzkin Chessmaster Strategy Section 7 - the mastery quiz.
Position: Black to move. (See here on chess.com)
[Event ""] [Site "?"] [Date "????.??.??"] [Round "?"] [White " "] [Black " "] [Result "*"] [SetUp "1"] [FEN "2b5/p5n1/1pBk3p/1P6/1K3p2/5P1N/6P1/8 b - - 0 1"]
Here's what happened:
Josh says trade bishop for knight and then do a5 check.
My answer is to do a5 check, but Josh says it is 'not quite right' to do a5 check 1st.
I checked this on the chess.com engine, which says both my answer and Josh's are 'best' moves (but technically the evaluation is slightly higher for Josh's answer).
Question 1: Is there a difference if I do check before the trade?
Question 2: Josh says a5 check is wrong ('not quite right' or something). So, Josh is wrong to say a5 check is wrong?
Note 2.1: There was a deleted comment by Hauke Reddmann saying White could possibly take e.p. and give up the bishop and do Nxf4. So there could be a knight and bishop (vs knight) ending (instead of knight vs bishop ending). Therefore, this a5 check is actually not as forcing as bishop takes knight, which definitely forces the trade or something.
- Note 2.1.1: This was converted into an answer.