Page 25, line 10.
"Take (P, Q) \in \mathcal{R}" should be "Take (P, R) \in \mathcal{R}"

Page 48: in the first rule, "$Q \in \mathcal{P}$" should be "$P \in \mathcal{P}$"
[thanks to Paul He]

Page 75: The solution to exercise 2.10.10 is not reported in Appendix A, as
erroneously indicated.

Page 216 (solution to Esercise 4.3.6): "C_1 -b> D" should be "C_1 -c> D".

Thanks to Paul He