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[主观题]
递归定义集合B如下:(1)( )∈B,(2)若x∈B,则(x)∈A,(3)若x,y∈B,则(xy)∈A,(4)只有有限次应用(1)~(3
递归定义集合B如下:(1)()∈B,(2)若x∈B,则(x)∈A,(3)若x,y∈B,则(xy)∈A,(4)只有有限次应用(1)~(3
递归定义集合B如下:
(1)()∈B,
(2)若x∈B,则(x)∈A,
(3)若x,y∈B,则(xy)∈A,
(4)只有有限次应用(1)~(3)得到的符号串属于B.
问下述符号出是不属于B.
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