theorem Th8:
  -(i|->c) = i|->-c
proof
  reconsider s=c as Element of COMPLEX by XCMPLX_0:def 2;
  -(i|->s) = i|->(compcomplex.s) by FINSEQOP:16
          .= i|->-c by BINOP_2:def 1;
  hence thesis;
end;
