When pawns are separated by more than three files, a sole knight is unable to stop them since it cannot achieve a relative blockade. In these situations the only viable drawing stratagem is “work distribution” – the knight takes care of one and the king of the other pawn. A very nice study on the theme was composed by N. Grigoriev in 1934. Despite the knight being boxed-in, White to move draws. The reason is that even so the knight serves the purpose since it makes Black use a couple of tempi. That is, prevents the advance of the h-pawn whilst giving the white king the time to take care of the passed b-pawn.
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