theorem Th22:
  S c= ==>.-relation(S)
proof
 let x be object;
    assume
A1: x in S;
    then consider a, b being object such that
A2: a in E^omega & b in E^omega and
A3: x = [a, b] by ZFMISC_1:def 2;
    reconsider a, b as Element of E^omega by A2;
    a -->. b, S by A1,A3;
    then a ==>.b, S by Th10;
    hence thesis by A3,Def6;
end;
