Kronecker's congruence explained
In mathematics, Kronecker's congruence, introduced by Kronecker, states that
\Phip(x,y)\equiv(x-yp)(xp-y)\bmodp,
where
p is a prime and Φ
p(
x,
y) is the modular polynomial of order
p, given by
\Phin(x,j)=\prod\tau(x-j(\tau))
for
j the
elliptic modular function and τ running through classes of imaginary quadratic integers of discriminant
n
