1.将以下文法消除左递归，分析符号串 i*i+i 。
并分别求FIRST集、FOLLOW集，和SELECT集
E -> E+T | T
T -> T*F | F
F -> (E) | i
FIRST集
FIRST(TE')={（，i }
FIRST(+TE')={ + }
FIRST(ε)={ ε }
FIRST(FT')={（，i }
FIRST(*FT')={ * }
FIRST((E))={（ }
FIRST((E)|i)={ i }
FOLLOW集
FOLLOW(E)={#，）}
FOLLOW(E')={ ）}
FOLLOW(T)={ + }
FOLLOW(T')={ + }
FOLLOW(F)={ * }
SELECT集
SELECT(E->TE')={（，i }
SELECT(E'->+TE')={ + }
SELECT(E'->ε)={ ）}
SELECT(T->FT')={（，i }
SELECT(T'->*FT')={ * }
SELECT(T'->ε)={ + }
SELECT(F->(E))={（ }
SELECT(F->i)={ i }
分析符号串 i*i+i
2.P101练习7（2）（3）文法改写，并分别求FIRST集、FOLLOW集，和SELECT集
(2) A->aABe|a
B->Bb|d
提取左公因子：A->aA' A'->ABe|ε
消除左递归：B->dB' B'->bB'|ε
1、 FIRST集：
First(aA') = {a}
First(ABe) = {A}
First(ε) = {ε}
First(dB') = {d}
First(bB') = {b}
First(ε) = {ε}
2、 FOLLOW集：
Follow(A) = {Be}
Follow(A') = {#}
Follow(B) = {e}
Follow(B') = {#}
3、 SELECT集：
Select(A->aA') = First(aA') = {a}
Select(A'->ABe) = First(ABe) = {A}
Select(A'->ε) = First(ε) = {ε}∪Follow(A') = {#}
Select(B->dB') = First(dB') = {d}
Select(B'->bB') = First(bB') = {b}
Select(B'->ε) = First(ε) = {ε}∪Follow(B') = {#}
(3) S->Aa|b
A->SB
B->ab
将A->SB代入S->Aa|b可得：S->SBa|b
消除左递归：S->bS' S'->BaS'|ε B->ab
2、 FIRST集：
First(SBa) = {S}
First(b) = {b}
First(bS') = {b}
First(BaS') = {B}
First(ε) = {ε}
First(ab) = {a}
2、 FOLLOW集：
Follow(S) = {B}
Follow(S') = {#}
Follow(B) = {a}
3、SELECT集：
Select(S->SBa) = First(SBa) = {S}
Select(S->b) = First(b) = {b}
Select(S->bS') = First(bS') = {b}
Select(S'->BaS') = First(BaS') = {B}
Select(S->ε) = First(ε) = {ε}∪Follow(S') = {#}
Select(B->ab) = First(ab) = {a}
课堂练习：
求以下文法的FIRST集、FOLLOW集和SELECT集。
（1）S->Ap
A->a |ε
A->cA
A->aA
FIRST集:
FIRST(Ap)→{a,c,p}
FIRST(a)→{a}
FIRST(ε)→{ε}
FIRST(cA)→{c}
FIRST(aA)→{a}
FOLLOW集:
FOLLOW(S)→{#}
FOLLOW(A)→{p}
SELECT集：
SELECT(S→Ap)={a,c,p}
SELECT(A→a)={a}
SELECT(A→ε)={p}
SELECT(A→cA)={c}
SELECT(A→aA)={a}
S->Ap
S->Bq
A->a
A->cA
B->b
B->dB
（2）S->Ap
S->Bq
A->a
A->cA
B->b
B->dB
FIRST集:
FIRST(a)→{a}
FIRST(b)→{b}
FIRST(cA)→{c}
FIRST(dB)→{d}
FIRST(Bq)→{b,d}
FIRST(Ap)→{a,c}
FOLLOW集:
FOLLOW(S)→{#}
FOLLOW(A)→{p}
FOLLOW(B)→{q}
SELECT集：
SELECT(S->Ap)={a,c}
SELECT(S->Bq)={b,d}
SELECT(A->a)={a}
SELECT(A->cA)={c}
SELECT(B->b)={b}
SELECT(B->dB)={d}