theorem Th95:
  A**(B++C) c= A**B ++ A**C
proof
  let a;
  assume a in A**(B++C);
  then consider c,c1 such that
A1: a = c*c1 and
A2: c in A and
A3: c1 in B++C;
  consider c2,c3 being Complex such that
A4: c1 = c2+c3 & c2 in B and
A5: c3 in C by A3;
A6: c*c3 in A**C by A2,A5;
  a = c*c2+c*c3 & c*c2 in A**B by A1,A2,A4;
  hence thesis by A6;
end;
