reserve p,q for Rational;
reserve g,m,m1,m2,n,n1,n2 for Nat;
reserve i,i1,i2,j,j1,j2 for Integer;
reserve R for Ring, F for Field;

theorem
for p being Prime,
    F being p-characteristic Field,
    E being Field st F includes E holds E includes Z/p
proof
let p be Prime, F be p-characteristic Field, E be Field;
assume F includes E;
then F is E-monomorphic by Th71;
then Char E = Char F by Th87 .= p by Def6;
then E is p-characteristic;
hence thesis by Th71;
end;
