minimax algorithm

[mo reina]

i'm having some problems tracing the minimax algorithm here... can anyone help me with a really simple walkthrough? particularly how the nodes are rated, i'm not quite sure how that's done. i tried setting SLDB to (declaim (optimize (debug 3))) and putting a (break) statement in the get-ratings function so that i could inspect the stack and step through but it would always result in a stack overflow so no cigar.