Question

In my grammars – Computer theory class I am trying to create a regular expression in alphabetical order(a-z)

l = {a, b, x, y, z, i, o, u, e, c}

This is what i have come up with using the kleene closure

aeiou(x*, y*, z*, i*, o*, u* e*) 

With the kleene close * thats zero or more so that should force abceioxyz?

We have not been learning this type of form

[^abc]

am i on the right track?

Answer 1

As far as I understand, you want to capture strings with the following format:

• The string contains any number of a‘s, afterwards any number of b‘s, then any number of c‘s, and so on…

Let’s consider a derived example: We want all strings consisting of 0 and 1 and that has all 0‘s before 1‘s: Therefore, we can simply write 0*1*. Now try to adapt the pattern for more complex alphabets.