编译程序第一个工作阶段-词法分析(NFA和DFA转换)

上篇讲述确定有穷自动机和不确定有穷自动机，本篇讲述不确定有穷自动机和确定有穷自动机之间的转换。从百度文库中找到一个示例感觉很合适。

如图所示：

1．具有ε动作的NFA状态转换表

2．分别求ε-closure

ε-closure（I）就是状态集I中，任意状态S经过任意的 ε能到达的状态集合。

ε-closure(0) = {0,1,2,4,7}
ε-closure(1) = {1,2,4}
ε-closure(2) = {2}
ε-closure(3) = {1,2,3,4,6,7}
ε-closure(4) = {4}
ε-closure(5) = {1,2,4,5,6,7}
ε-closure(6) ={1,2,4,6,7}
ε-closure(7) = {7}
ε-closure(8) = {8}
ε-closure(9) = {9}

3．转换算法：

move（I，a）是从I中的某一状态经过一条a弧而到达的状态全体。

ε-closure(0) ={0,1,2,4,7} = A
ε-closure(move(A,a))=ε-closure({3,8})={1,2,3,4,6,7,8} = B
ε-closure(move(A,b))=ε-closure({5})={1,2,4,5,6,7} = C
ε-closure(move(B,a))=ε-closure({3,8}) = B
ε-closure(move(B,b))=ε-closure({5,9})={1,2,4,5,6,7,9} = D
ε-closure(move(C,a))=ε-closure({3,8}) = B
ε-closure(move(C,b))=ε-closure({5}) = C
ε-closure(move(D,a))=ε-closure({3,8}) = B
ε-closure(move(D,b))=ε-closure({5}) = C

4．DFA的转换表

5．状态转换图

本篇到这里，编译原理入门教程就到这里了。