We have reached the final destination of our journey into unification grammars, and can pause and look back at what we have done. Our main purpose has been the presentation of a powerful formalism for specifying grammars, for both formal and natural languages. In doing so, we intended to combine insights from both linguistics and computer science.

From linguistics, we have adopted various analyses of complex syntactic constructs, such as long-distance dependencies or subject/object control, that prevail in natural languages and are easily recognized as inadequately represented, say, by context-free grammars. Several linguistic theories deal with such constructs; a common denominator of many of them is the use of features (and their values) to capture the properties of strings, based on which a grammar can be specified. However, the use of features is mostly informal. The formalism we presented adopts (from linguistics) feature structures as its main data-structure, but with a rigorous formalization. As a result, claims about grammars can be made and proved. We believe that resorting to proofs (in the mathematical sense) should become a major endeavor in any study of theoretical linguistics, and the ability to prove claims should be a major ingredient in the education of theoretical linguists. By understanding its underlying mathematics, one can better understand the properties of the formalism, recognizing both its strengths and weaknesses as a tool for studying the syntax of natural languages.

From computer science, we took several insights and adapted them to also suit the analysis of natural language.