P. D. Magnus’s forall x has been around for over a decade, and because it’s open, people can use it as a starting point for derivative versions with different features.
The new edition of forall x will be posted soon. Anybody who has used the book before will find the changes so small as to make almost no difference, but I wanted to discuss what I did beyond correcting typos. First, I’ve changed the formatting a bit. Second, I’ve changed the notation for substitution instances in proofs (again). Third, I’ve changed the license to be even more permissive.
It’s been over a decade since I released the first edition of the open access logic textbook forall x. It’s been a few years since my last update, because it’s been a few years since I last taught logic.
A number of people have made their own editions of forall x over the years, but 2017 was a breakout year: Continue reading “A big year, forall x”