Wikipedia 10K Redux

Reconstructed by Reagle from Starling archive; see blog post for context.

ModularArithmetic

The ModularArithmetics are the images of the IntegerNumbers under group/ring HomoMorphisms. Such an operation is going to zero out some NormalSubgroupIdeal, and these turn out to be precisely the sets of the form pZ for some integer p; the resulting group/ring is denoted Zp.

To put it another way, Zp consists of the remainders {0,1,...,p-1}, so that p=0. For instance, Z3 has the following addition and multiplication tables:

0+0=0 1+0=1 2+0=2

0+1=1 1+1=2 2+1=0

0+2=2 1+2=0 2+2=1

0*0=0 1*0=0 2*0=0

0*1=0 1*1=1 2*1=2

0*2=0 1*2=2 2*2=1

When p is a composite number, the factors of p are going to turn out to be ZeroDivisors. When p is prime, these don't exist, and so Zp is an IntegralDomain and in fact necessarily a field.