@palladin: thanks! vlepontas to notation sto kefalaio 19 tou Harper, katalhgw sto symperasma oti prepei na diavasw ta prwta 18 kefalaia gia arxh 🙂

@stathissideris: Nai thelei kapoia eksikiosi me inductive definitions kai Gentzen style natural deduction.

https://gist.github.com/mfikes/844a9e6659a30eaf44dcb9170ebc739d ενδιαφερον!