In GB, the importance of phrase-structure rules has dwindled in favour of nearness conditions. Today, nearness conditions play a major role in defining the correct linguistic representations. They are expressed in terms of special binary relations on trees called command relations. Yet, while the formal theory of phrase-structure grammars is quite advanced, no formal investigation into the properties of command relations has been done. We will try to close this gap. In particular, we will study the intrinsic properties of command relations as relations on trees as well as the possibility to reduce nearness conditions expressed by command.
