Wrong function.
Equivalences as conjunctions of implications.
No-repetition ruleset.
Are these moves equal?
Define the no-repetition variant of E.
Better MAKE-VARIABLE (as generic function).
Is this a generalization?
Is this a universal generalization?
Is this an existential generalization?
More concise implementation of EQUAL-FORMULAS?.
How to deal with atoms and generalizations at the propositional level.
D and E, in a first-order way.
Use EQUAL-FORMULAS? as a test.

We don't have perfect indexing yet.
Instantiation, gathering terms and variables.
Terms in moves and symbolic attacks.
Terms in a dialogue.
Don't shy away from FOL.