Abstract Machine for Typed Feature Structures
  This paper describes a first step towards the definition of an abstract machine for linguistic formalisms that are based on typed feature structures, such as HPSG. The core design of the abstract machine is given in detail, including the compilation process from a high-level specification language to the abstract machine language and the implementation of the abstract instructions. We thus apply methods that were proved useful in computer science to the study of natural languages: a grammar specified using the formalism is endowed with an operational semantics. Currently, our machine supports the unification of simple feature structures, unification of sequences of such structures, cyclic structures and disjunction. 
Shuly Wintner (Technion, Israel Institute of Technology) and Nissim   Francez (Technion, Israel Institute of Technology)