  This paper presents a compilation procedure which determines internal and
external indices for signs in a unification based grammar to be used in
improving the computational efficiency of lexicalist chart generation. The
procedure takes as input a grammar and a set of feature paths indicating the
position of semantic indices in a sign, and calculates the fixed-point of a set
of equations derived from the grammar. The result is a set of independent
constraints stating which indices in a sign can be bound to other signs within
a complete sentence. Based on these constraints, two tests are formulated which
reduce the search space during generation.
