  The paper presents some aspects involved in the formalization and
implementation of HPSG theories. As basis, the logical setups of Carpenter
(1992) and King (1989, 1994) are briefly compared regarding their usefulness as
basis for HPSGII (Pollard and Sag 1994). The possibilities for expressing HPSG
theories in the HPSGII architecture and in various computational systems (ALE,
Troll, CUF, and TFS) are discussed. Beside a formal characterization of the
possibilities, the paper investigates the specific choices for constraints with
certain linguistic motivations, i.e. the lexicon, structure licencing, and
grammatical principles. An ALE implementation of a theory for German proposed
by Hinrichs and Nakazawa (1994) is used as example and the ALE grammar is
included in the appendix.
