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Twin Problem 6: Mate in 2 Moves

(White: Kh4, Qb6, Rb3, Bd6, Ng4, Ng7, a2, g2, Black: Kd5, Ra4, Ba7, b5.)

White to move and mate in 2

Now, replace white knight g4 with white bishop and move white pawn a2 to b2:

(White: Kh4, Qb6, Rb3, Bd6, Bg4, Ng7, b2, g2, Black: Kd5, Ra4, Ba7, b5.)

White to move and mate in 2

Solution