I think, it describes word a

but you have wa...
I think that if for "abc" power of set will be (1 * 1 * 1) = 1, for "ab(c|d)" power will be (1 * 1 * 2) = 2, than for (a0) power of set will be 1 * 0 = 0

But why power of the empty set is equal to 0? I think, it is equal to 1...

Some hints:
1) power of set (a0) is 0
2) By statement, "it means (if there is '*') <symbol>0|<symbol>1|…|<symbol>n|… (arbitrarily many times) where <symbol>i means <symbol><symbol>…<symbol> (i times) and

<symbol>0 means the set consisting of one empty word
",
  so power of set (0)* is 1, and set (a)* is inifnite

Edited by author 23.09.2007 17:00

Thanks

0 does not mean the set consisting of one empty word, but rather it means an empty set of words. Still, there is a way to obtain a set consisting of one empty word.

Edited by author 14.07.2008 18:49

Edited by author 14.07.2008 18:49