Regular Expressions?

[cdietschrun]

What does this mean?

"Considering the language L: strings over {a,b} such that they contain even number (including 0) of a's. Write a regular expression corresponding to L."

This is part of a practice exam for a final for a computing class. We worked with regular expressions in such a tiny amount that this Q confuses me. I'm aware of regular expressions like ( something ) ? | (something_else)* | (something_else_yet)+ meaning how many times they expect to see one of those..zero or more or 1 or more...

Can anyone shed light on this q?

 

[cdietschrun]

anyone?

 

[Pookymeister]

ah regular expressions.

I know a few :

:lol:#




i haven't done it in a while so dont know the format, but it's probably something like

B* | (AA)* | (ab*a)*

 

[cdietschrun]

Yea, that's about what I had...but I have an entire page to answer, and I have no idea why. I can't think of anything else.

Then the next page gives me this one:

"The following grammar generates regular expressions over the alphabet {a,b,c}:
R -> R + R | RR | R* | a | b | c
Draw two different parse trees that can match with the string A+b*C. On the parse tree, label the grammar rules that you choose with the matching subtrees."

...What?

 

[epobirs]

Use google to find some lengthy blathering articles on the subject. Then synthesize something seemingly original from those so as to avoid accusations of plagiarism.

Such as: http://www.regular-expressions.info/

 

[homeland]

did you try asking in yahoo answers? Thats how I got alot of my math problems answered.