why start operating of empty language equal empty element?

Question

i am learning about compilation , analyse lexical and such things .

in something named rational expression ! it's something like regular expression there is a rule i can't understand it , i find it illogical ! the rule said that the start operating of empty language is the empty element .

Answer 1

It is not the "start setting" but the star operation applied to the empty set. The result is indeed the set $\{\epsilon\}$. Look at the definition of the Kleene star in wikipedia for more details.