Error at page 83-84: Chapter 2.3, Exercise 41

[MetallicCrimson]

Small typo, but in the 1st part of the proof, the second row: ∼p by premise (c) should be ∼t by premise (c).

[spamegg1]

Thanks! Piling up a few typos and mistakes for now, to make a fix/release. I'll do it around New Year's!