We present sufficient conditions for when an ordering of universal cycles $\alpha_1, \alpha_2, \ldots, \alpha_m$ for disjoint sets $\mathbf{ S}_1, \mathbf{ S}_2, \ldots , \mathbf{ S}_m$ can be concatenated together to obtain a universal cycle for $\mathbf{ S} = \mathbf{ S}_1 \cup \mathbf{ S}_2 \cup \cdots \cup \mathbf{ S}_m$. When $\mathbf{ S}$ is the set of all $k$-ary strings of length $n$, the result of such a successful construction is a de Bruijn sequence. Our conditions are applied to generalize two previously known de Bruijn sequence constructions and then they are applied to develop three new de Bruijn sequence constructions.
Categories: math.CO