作业2解答-编译原理作业答案(共2页).doc

精选优质文档-倾情为你奉上2.1 设字母表A=a，符号串x=aaa，写出下列符号串及其长度：x0,xx,x5以及A+.x0=(aaa)0= | x0|=0 xx=aaaaaa |xx|=6x5=aaaaaaaaaaaaaaa | x5|=15A+ =A1 A2 . A n =a,aa,aaa,aaaa,aaaaa A* = A0 A1 A2 . A n =,a,aa,aaa,aaaa,aaaaa 2.2 令=a，b，c，又令x=abc，y=b，z=aab，写出如下符号串及它们的长度：xy，xyz，（xy）3xy=abcb |xy|=4xyz=abcbaab |xyz|=7(xy)3=(abcb)3 =abcbabcbabcb | (xy)3 |=122.3 设有文法GS：S=SS*|SS+|a，写出符号串aa+a*规范推导，并构造语法树。S=SS*=Sa*=SS+a*=Sa+a*=aa+a*