Arabic Relative Clauses in HPSG

In HPSG relative clauses have been analyzed in terms of phonologically empty heads in Pollard and Sag (1994) and in terms of a complex system of phrase types in Sag (1997). Modern Standard Arabic has a distinction between relative clauses with a definite antecedent, which are introduced by a special complementizer, and relative clauses with an indefinite antecedent, which are ?bare? clauses. Analyses eschewing empty heads and assuming a complex system of phrase types face a number of problems. An analysis in which relatives with an indefinite antecedent are headed by a phonologically empty complementizer is more satisfactory. Thus, in the case of Arabic, the approach of Pollard and Sag (1994) seems preferable to the approach of Sag (1997).