Syntax and Semantics for FOL material has become too technical

Based on my experience teaching with the Fall 2017 version of Sets, Logic, Computation I think the material on syntax and semantics for FOL has become inaccessible to students with a single prior formal logic course like those in our Phil 379. Many of those students have no experience at all with formal models, but recent changes to the text have focused on adding to the body of proved theorems and providing technical scaffolding for material needed in more advanced logic classes. I'm not sure how to thread the needle here for the needs of these students versus what is needed in these sections for students in graduate logic classes. But you asked me to file it Richard, so here it is.

Start by reviewing the textbook's syntax and semantics for FOL material and compare it with the Fall 2017 version mentioned in the issue. The issue does not name files or tests; done requires an agreed revision that is accessible to students with one prior logic course while retaining material needed for graduate logic classes.