Tree adjoining and head wrapping
K. Vijay‐Shanker, David James Weir, Aravind K. Joshi · 1986
In this paper we discuss the formal relationship between thw classes of languages generated by Tree Adjoining Grammars and Head Grammars. In particular, we show that Head Languages are included in Tree Adjoining Languages and that Tree Adjoining Grammars are equivalent to a modification of Head Grammars called Modified Head Grammars. The inclusion of MHL in HL, and thus the equivalence of HG's and TAG's in the most general case remains to be established.