Group division G/N is defined if N is normal

G/N = cosets of N in G.

example: D3/C3

forall g,g1,g2 in G

NN=N => (gN)N=gN

NgN=gN

g1Ng2N=g1g2N

(gN)^=g^N

example: C3 subset of D3 normal

D3/C3= {N,bN} ~= C2

source

jl@crush.caltech.edu index

normal_subgroup