reserve a,b,n for Element of NAT;

theorem Th36:
  for a,b,n being Element of NAT holds GenFib(a,b,n+2) + GenFib(a,
  b,n+3) = GenFib(a,b,n + 4)
proof
  let a,b,n be Element of NAT;
  GenFib(a,b,n+2) + GenFib(a,b,n+3) = GenFib(a,b,(((n+1)+1)+1)+1) by Th32
    .= GenFib(a,b,n + 4);
  hence thesis;
end;
