Mixed Chaining

• For this case, and quite often in other moderately complex cases, you want to use mixed chaining.
• You want to use forward chaining, and backward chaining and see where they meet.
• If in each case you have two possible moves, and you have to make ten moves, how many cases do you have to explore?
• 2+4+8+16+...+512+1024.
• This works for both forward and backward chaining.
• However, if you interleave you only have to try
• 2+4+8+16+32+2+4+8+16+32
• If however, in the forward case there are 10 possibilitities, and in the backward only 2, you want to use backward chaining. The reverse is also true.
• The forward direction is called fan-out, and backward fan-in.