|notyetagm: Position after 21 ... ♗e6xd5! 22 e5-e6
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The idea of 22 e5-e6 is to prevent Black from supporting the <PINNED> Black d5-bishop with 22 ... e7-e6. Allowing 22 ... e7-e6 would give
the Black d5-bishop a secure <FOUNDATION PAWN>.
This great example shows you how important the concept of the <FOUNDATION PAWN> is when it comes to <PINNED PIECES>. If the <PINNED> piece can be defended by a pawn (<FOUNDATION PAWN>) and not be attacked by a pawn, then it is almost impossible to exploit the <PINNED> piece as a <TARGET>; however, the <PINNED> piece can still be exploited as not being a <DEFENDER> (as 22 e5-e6 shows).
Also notice the importance of <TEMPO FOR DOUBLING>, as in the brilliant miniature Ivanchuk vs Anand, 2007. If White could play two moves in a row after ... Be6xd5!, then e5-e6 (<NO FOUNDATION PAWN>) and Qe2-d2 (doubling on d-file) would win the Black d5-bishop. So this means that White would need to double on the d-file <WITH TEMPO>, i.e., 23 ♕e2-d2 would need to threaten something -other- than the Black d5-bishop; since he cannot, the Blackd d5-bishop is safe.