Discreteness and completeness for $\Theta_n$-models of $(\infty,n)$-categories

We establish cartesian model structures for variants of $\Theta_n$-spaces in which we replace some or all of the completeness conditions by discreteness conditions. We prove that they are all equivalent to each other and to the $\Theta_n$-space model, and we give a criterion for which combinations of discreteness and completeness give non-overlapping models. These models can be thought of as generalizations of Segal categories in the framework of $\Theta_n$-diagrams. In the process, we give a characterization of the Dwyer-Kan equivalences in the $\Theta_n$-space model, generalizing the one given by Rezk for complete Segal spaces.