Randomized and Approximate Algorithms 535
The certifi cate testing function, which is not given here, is chosen in such a way that it is fast and also the
probability of it missing to identify N as a composite is less than 1/2. We have given a primality test program
with a simple (but not very dependable) certifi cate routine in
primtest.c. It is able to reject Carmichael
numbers like 561, 1105, and 1729.
19.3 RANDOMIZED COMPLEXITY CLASSES
In this section we shall look at some randomized complexity classes: RP, co-RP, ZPP, and BPP. We begin with
a brief review of P and NP.
There is a good complexity resource on the web at http://www.complexityzoo.com/. This site
contains, at last count, defi nitions of 406 complexity classes, including brief discussions ...