Question

write a regular expression for the language containing a string in which 4th character from right end of the string is always 'b' over a,b
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Answer 1

Answer:

Sol

Write regular expressions for the following languages over the alphabet Σ = {a, b}:. (a) All strings that do not end with aa. ϵ + a + b ... (b) All strings that contain an even number of b's. a . ∗.