Splitting of c.e. degrees and superlowness

In this paper, we show that for any superlow c.e. degrees $\mathbf{a}$ and $\mathbf{b}$ there exists a superlow c.e. degree $\mathbf{c}$ such that $\mathbf{c}\not=\mathbf{a}_0\cup\mathbf{b}_0$ for all c.e. degrees $\mathbf{a}_0\leqslant\mathbf{a}$, $\mathbf{b}_0\leqslant\mathbf{b}$. This provides one more elementary difference between the classes of low c.e. degrees and superlow c.e. degrees. We also prove that there is a c.e. degree that is not the supremum of any two superlow not necessarily c.e. degrees.