COMPUTER SCIENCE AND ENGINEERING
COMPILER DESIGN
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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zero or more occurrences of a and b
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zero or more occurrences of a or b
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one or more occurrences of a and b
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letter a followed by zero or more occurrences of b
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Detailed explanation-1: -Save this answer. Show activity on this post. In normal regular expression grammar, (a+b)* means zero or more of any sequence that start with a, then have zero or more a, then a b .
Detailed explanation-2: -The * is an occurrence indicator representing zero or more occurrences. Together, [1-9][0-9]* matches any numbers without a leading zero. | represents the OR operator; which is used to include the number 0 . This expression matches “ 0 “ and “ 123 “; but does not match “ 000 “ and “ 0123 “ (but see below).
Detailed explanation-3: -Solution: As we know, any number of a’s means a* any number of b’s means b*, any number of c’s means c*. Since as given in problem statement, b’s appear after a’s and c’s appear after b’s. So the regular expression could be: R = a* b* c*