Added tag Isabelle2019-RC4 for changeset ad2d84c42380
package Greatest_Common_Divisoris --# function Gcd(A, B: Natural) return Natural; procedure G_C_D(M, N: in Natural; G: out Natural); --# derives G from M, N; --# pre M >= 0 and N > 0; --# post G = Gcd(M,N);end Greatest_Common_Divisor;