reserve x,y,y1,y2 for set;
reserve G for Group;
reserve a,b,c,d,g,h for Element of G;
reserve A,B,C,D for Subset of G;
reserve H,H1,H2,H3 for Subgroup of G;
reserve n for Nat;
reserve i for Integer;
reserve L for Subset of Subgroups G;

theorem Th106:
  x in con_class H implies x is strict Subgroup of G
proof
  assume x in con_class H;
  then ex H1 being strict Subgroup of G st x = H1 & H,H1 are_conjugated by
Def12;
  hence thesis;
end;
