Syntactic Theory
Government
governs
if and only if
i)
is a governor; and

ii)
m-commands
; and


iii) no barrier intervenes between
and
.


Maximal projections are barriers to government. Governors are heads.
There is a refined notion of government which is particularly important for Case-theory. It is the same as the one above, except that the notion of governing head is specified individually:
Lexical heads (V0, N0, P0, A0) and tensed I0 are governors.