Well-nested parallelism constraints for ellipsis resolution

The Constraint Language for Lambda Structures (CLLS) is an expressive tree description language. It provides a uni-form framework for underspecified se-mantics, covering scope, ellipsis, and anaphora. Efficient algorithms exist for the sublanguage that models scope. But so far no terminating algorithm exists for sublanguages that model ellipsis. We introduce well-nested parallelism con-straints and show that they solve this problem.