正则表达式的例子 Σ={a,b} L(ab)=fa,bg L(ab(ab)=aa, ab, ba, bb) L(a)=s, a, aa, aaa, aaaa (ab )=e, a, b, aa, ab, ba, bb, aaa, aab L(aa b)=fa, b ab, aab, aaab,.)正则表达式的例子 • Σ={a,b} • L(a|b) = {a,b} • L((a|b)(a|b)) = {aa,ab,ba,bb} • L(a*) = {ε,a,aa,aaa,aaaa,……} • L((a|b)*) = {ε,a,b,aa,ab,ba,bb, aaa,aab,……} • L(a|a*b) = {a,b,ab,aab,aaab,…}