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;

theorem Th91:
  A,B are_conjugated & B,C are_conjugated implies A,C are_conjugated
proof
  given g such that
A1: A = B |^ g;
  given h such that
A2: B = C |^ h;
  A = C |^ (h * g) by A1,A2,Th47;
  hence thesis;
end;
