- Fully accessible HTML version and SCORM packages using BookML (issue 23). This required many changes under the hood; see the blog post on technical details.
- Proofs now label premises by PR and assumptions by AS (helps with accessibility, and makes textbook match Carnap's conventions more closely).
- New chapter 13 (Limitations of TFL) based in part on section 12.5 of F21 edition.
- New chapter 35 (Properties of relations)
- Removed confusing sketch of soundness proof from chapter 22 (issue 66)
- Moved section 30.4 (Satisfaction of formulas) to section 32.2 (Expressibility) and expanded it.
- Added solutions to problems in chapters 7 and 29 (Ambiguity)
- Added explanation on quantifier restriction at end of section 25.4 (issue 57)
- Added material to section 27.3 on vacuous quantification, revised definitions of substitution to substitute only free occurrences of variables, and added section 36.6 to explain what can go wrong if you're not careful with substitution (issue 77)
- Revisions to section 4.2 to bring it in line with the terminology of chapter 3.
- Added brief discussion of asymmetric use of “and” in section 5.2
- Many minor revisons, fixed typos, and fixed formatting
- Add chapter 45 on chains of equivalences
- Add discussion of “only” and “except” to chapter
- Lots of spelling, grammar fixes
- Notes for instructors in Preface
- some behind-the-scenes reorganization of the files (e.g, it now
uses a stock
fitch.sty,forallxyyc-style.stywith just the formatting stuff separate fromforallxyyc.styso the latter can be used in beamer slides) - renamed “expressively adequate” to “functionally complete”
- incorporated some changes from the Cambridge version
- moved chapter “Sentences of FOL” to before the “Definite descriptions” chapter
- added two chapters on ambiguity (7, 28)
- added “only” to section 23.1
- split the chapter on normal forms and functional completeness into two
- corrected some typos
- New cover design by Mark Lyall.
- Rewritten/revised chapters 1–3, avoiding modality when defining validity and instead talk about “cases” (the way JC Beall and Shay Logan do in their book, Logic: The Basics).
- Changed the syntax of FOL: formulas are now F(x, y) instead of Fxy. This can be customized in forallxyyc-local.sty, though.
- Changed some terminology: “logical consistency” is now “satisfiability” (and cognates), “logical truths” are now “validities”.
- Sentence letters now allowed in FOL formulas.
- Reiteration is now a basic rule, so that proofs can be in normal form.
- Chapter 28 now defines satisfaction of a formula by an object, so that truth conditions for quantifiers can be stated more cleanly.
- New chapters 16, 33 on strategies for constructing proofs.
- Added three chapters on modal logic (natural deduction proof system and Kripke semantics). They are based on A Modal Logic Primer by Rob Trueman (University of York), which he was generous enough to share. I’ve changed his proof system to use Fitch’s modal rules. It covers the basics of K, T, S4, and S5.
- Added a chapter on soundness for TFL proofs, from Tim Button’s Metatheory.
- Corrected various errors and added various clarifications.