Let S and T be language over Σ = {a, b} represented by the regular expressions…

2000

Let S and T be language over Σ = {a, b} represented by the regular expressions (a + b*)* and (a + b)*, respectively. Which of the following is true?

  1. A.

    S ⊂ T

  2. B.

    T ⊂ S

  3. C.

    S = T

  4. D.

    S ∩ T = ∅

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Correct answer: C

The regular expression (a + b)* generates all possible strings over the alphabet {a, b}, representing Σ*. Similarly, (a + b*)* generates all strings in Σ* because it includes 'a' and allows any number of 'b's. Thus, both languages S and T are equivalent.

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