Parallelism constraints

Abstract

Parallelism constraints are logical descriptions of trees. They are as expressive as context unification, i.e. second-order linear unification. We present a semi-decision procedure enumerating all “most general unifiers” of a parallelism constraint and prove it sound and complete. In contrast to all known procedures for context unification, the presented procedure terminates for the important fragment of dominance constraints and performs reasonably well in a recent application to un-derspecified natural language semantics.