Consider the following position with white to move. What is the best move?
White clearly has a significant advantage. In fact, this position is a win for white.
Any move by white still results in a position that is a win for white. So what is the best move? Some will point out that white can mate in two starting with either Ra3, Rb3, Rd3, Re3, Rf3, or Rg3.
But why is Rd3, for example, better than Kf3? Refer back to Part 1 in this series regarding time, energy, and efficiency for the answer! I now propose the following decision rule:
1.2 If multiple moves lead to forced mate, then make a move that leads to the shortest forced mate. If your opponent can force mate, then make a move that requires the longest forced mate.
If we agree to this rule, then we know that the best move is one of the above rook moves. We won’t get too pedantic about which move is best. We’ll pick 1. Rd3.
Now black only has one move – there is no decision to be made. So black responds with 1. … Kh1. Then white plays 2. Rh3# based on Rule 1.1 (although Rule 1.2 also applies)