COMPUTER SCIENCE AND ENGINEERING
THEORY OF COMPUTATION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
b*a*
|
|
|
(a*b*)*
|
|
|
(a*b*)*
|
|
|
a*b*
|
Detailed explanation-1: -So, a+b means [ab] or a|b, thus (a+b)* means any string of length 0 or more, containing any number of a s and b s in any order. Likewise, (a*b*)* also means any string of length 0 or more, containing any number of a s and b s in any order. The two expressions are different ways of expressing the same language.
Detailed explanation-2: -Regular expressions are equal if and only if they correspond to the same language. Thus for example ( a + b )* = ( a*b* )*, because they both represent the language of all strings over the alphabet a, b.
Detailed explanation-3: -We say that two regular expressions R and S are equivalent if they describe the same language. In other words, if L(R) = L(S) for two regular expressions R and S then R = S. Examples.
Detailed explanation-4: -It is equivalent to the Nd regular expression pattern, which includes the standard decimal digits 0-9 as well as the decimal digits of a number of other character sets. If ECMAScript-compliant behavior is specified, ịs equivalent to [0-9].