I read the book of titled "a mathematical introduction to logic" written by Enderton at pp.184-185.
i don't understand thm 30A's proof procedure. i understand proof's way intended that constructs some formula σ that it says itself can't be deduced from A. but i understand next procedure about def of relation R in proof : " ... and c is the value of G at some deduction from of α(S^b0)" (because the book says G means Godel number of deduction but i can't understand α(S^b0)'s means")
so then i can't understand what the proof say except proof's intention.
so i want to know what does R means and how a given proof procedure solves the theorem, i.e. why formula σ can be expressed that σ does not have deduction from A.
