Key:
Transgressive (Diverse): A tree that minimizes the maximum number of questions asked. Attempts to ask about as many distinct letters as possible.
Transgressive (Homogeneous): A tree that minimizes the maximum number of questions asked. Attempts to ask about as few distinct letters as possible both throughout the tree and for the nth question across all branches for all n.
Commutative: A tree that minimizes the total number of letters asked about across all branches. The same letter must appear for the nth question on each branch.
Progressive: A tree that minimizes the maximum number of incorrect guesses, the average number of incorrect guesses per answer, and the lateness of incorrect guesses. Also attempts to be homogeneous (as above).
Frontloaded Progressive: A tree that minimizes the number of incorrect guesses following the first correct guess and secondarily the maximum and average number of incorrect guesses per answer. Also attempts to be homogeneous (as above).