Multiple choice

Consider the set $ \sum^* $ of all strings over the alphabet $ \sum $ = {0, 1}. $ \sum^* $ with the concatenation operator for strings

  1. does not form a group

  2. forms a non-commutative group

  3. does not have a right identity element
  4. forms a group if the empty string is removed from $\sum^*$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let p denote the set of all non -empty strings of letters from M Where, M = { $\alpha , \beta , \gamma $ } We have P = { $\alpha , \beta , \gamma ,\alpha ,\alpha ,\alpha ,\pi ,\alpha ,\gamma ,........\alpha ,\alpha ,\alpha ,\alpha ,\alpha ,\beta ....$ }

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