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Reversible Unification Grammars
A unification grammar defined in formalisms such as PATR II and
DCG [12] usually
defines a relation between a string of words and a logical form.
In sign-based approaches such as UCG [26] and HPSG [14] this string of
words is not assigned a privileged status but is the value of one
of the attributes of a feature structure.
I will assume a formalism similar
to PATR II, but without the context-free base; the string is represented
as the value of one of the attributes of a feature structure.
Thus more generally, unification grammars define relations between the values of two (or
more
) attributes - for example
the relation between the value of the attributes 
and
, or between the value of the attributes 
and 
; these relations are all relations between feature
structures.
Gertjan van Noord
Fri Nov 25 13:42:02 MET 1994