let p be a rational prime,K a number field.
Dedekind's discriminant theorem tells us:
p ramifies in K <==> p divides discriminant of K.
hence if p does not divide discriminant of K,
(p) will either splits,i.e.(p)=P_1P_2 (P1=/= P2)
or (p) remains prime.
now,my question is :
there are some criterias which can tell if p will split or remain prime.