ABSTRACT
In this chapter, we present a miniature version of the COACH program. Like CHEF, COACH tries to repair a failing plan, but in a very different way. Plan repair in CHEF is guided by the explanation of a plan failure. If the broccoli got soggy because it was cooked with the beef, then don't cook it with the beef! In COACH, the explanations are not adequate to suggest a repair that works. The bootleg run play fails because the defensive cornerback tackles the quarterback. Possible repairs, such as assigning a blocker to the cornerback, or running a different way, don't work. The cornerback is too far from any available blocker, and running another way would just cause the quarterback to be tackled by some other defensive man. The sweep play fails because the defensive cornerback tackles the halfback. Again, the available repairs for stopping a tackle don't work.
