Re: RR*=R* ?

On Mar 27, 4:21 pm, "Ravi" <ra.ravi....@xxxxxxxxx> wrote:
The text books on regular expressions show that:
RR*=R*

What I feel is that
RR*=R(є + R + R^2 + R^3 ... )
=R + R^2 + R^3 + R^4 ...
=R+
=R* - {є}

How come RR*=R* is true?

R+ is NOT equal to R* -{e}.
Take R={e,a}
R* = {e,a,a^2, ... }
R+ = {e,a,a^2,... }
Both are equal :)

In essence R* = R+ iff {e} is present in the set.

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