Variations on a Proof by Smullyan
Two weeks ago, I gave a rather hurried explaination of formalizing a
seemingly straightforward proof of the existence and uniqueness of Boolean
valuations as given in Raymond M. Smullyan's First-Order Logic. This
week we'll explore the proof and variations thereof in more detail.
Various issues will arise: interpreting an informal argument for
formalization, specifications and extractions vs. explicit witnesses, etc.
We hope to conclude with an elegant solution using very dependent function