Question

Which one of the following languages over the alphabet {0,1} is described by the regular expression

(0+1)* 0 (0+1)* 0 (0+1)* ?

a.The set of all strings that begin and end with either 0 or 1

b.The set of all strings containing at most two zeros

c.The set of all strings containing at least two zeros.

d.The set of all strings containing the substring 00

Answer 1

Option C is correct because in the given regular expression (0+1)* 0(0+1)* 0 (0+1)* the underlined two zeros will definitely be written.

Option A is incorrect because the given regular expression cannot yield 01 which is essential to satisfy option A.

Option B is incorrect because the given expression can generate 000 which rules out the possibility of B being correct.

Option D is incorrect because the given expression can also produce 11010 which does not include the substring 00.