How to find the FIRST set

E→TE’
E’→+TE’|ε
T→FT’
T’→*FT’|ε
F→(E)|i

$The$
method ofobtaining the$F$$I$$R$$S$$T$ set isas follows:
1.$X\in VT$ (terminal symbol set)
$FIRST(X)=X$ (ie: the FIRST set of the terminator is still itself).

2、$X\in VN$ (the set of non-terminal symbols)
(1) If$X\to a\dots$ , Then a join$FIRST\left(X\right)$ ; if there is$X\to \epsilon$ , then ε is added to$FIRST\left(X\right)$ (a is the first terminal symbol X can be introduced).
(2) If X→Y..., and Y∈VN, thenFIRST (Y) FIRST(Y)All non-ε elements in$F$$I$$R$$S$$T$$($$Y$$)$ are added to$FIRST\left(X\right)$；
（3） 若有$X\to {AND}_1{AND}_2{AND}_3\dots {AND}_K$,且${AND}_i\in VN$ ,$e\in FIRST(Yj)$ ，则$FIRST(Y_i)\; The$ non-ε element in themiddle isadded to$FIRST\left(X\right)$ ; if all$FIRST\left(Yj\right)$ all contain$\epsilon$， 则$\epsilon$加入$FIRST(X)。$