Hi guys. Gotta a CS exam coming up this sunday and I want to clarify the difference between bigO and theta notation. I know that bigO is the upperbound and it has a constant after which all running time will be below. I know that theta has an upper and lower bound for this running time, but I'm still a bit confused. Here are some questions:

1) Do big-oh and theta both represent the worstcase for the running time?

2) How do I know when to use theta? I know it is better to use but how do I know when I can use it? Could someone give a simple example of when to use theta?

thanks in advanced,

arh