Q: Projective space $Proj$ We let $S$ be a graded algebra. 
I have a 2 questions regarding the Proj construction. 


*

*It seems to me that we do not know what $O_{Proj S}Proj(S))$ is ?

*How is the map $S_0 \rightarrow \Gamma(Proj S, O_{Proj(S)})$ induced? 

