# regular expression with kleene closure [duplicate]

my question is if my regular expression R is 1* that means the language accepted is {^,1,11,111,1111...}

in that case i don't understand the meaning what (R*)* means

• @Steven thanks i got it..! – big hero Jun 29 '19 at 0:18
• Essentially $1^*$ means "any word consisting of any (finite) number of ones". If R is a RE and L(R) is its language, then R^* is "any word consisting of the concatenation of any (finite) number of words in L(R)". For example if $R = a+b$ then $R^*$ contains the word "abba" as it is the concatenation of "a", "b", "b", and "a", all of which are in $L(R) = \{a, b\}$. Going back to your case, you have $R = 1^*$ so $R^* = (1^*)^*$ is "any word obtained by concatenating any (finite) number of words containing only ones"... a convoluted way to say "any word containing only ones". – Steven Jun 29 '19 at 0:21
• Oh.. I see you edited your comment. Glad the other thread helped. – Steven Jun 29 '19 at 0:21