2 Overview

The XDG Development Kit (XDK) is a grammar development environment for the meta grammar formalism of Extensible Dependency Grammar (XDG). XDG is described most thoroughly in Ralph Debusmann's dissertation Extensible Dependency Grammar - A Modular Grammar Formalism Based On Multigraph Description. The XDK is published in The XDG Grammar Development Kit (References).

Still more XDG material can be found here: http://www.ps.uni-sb.de/~rade/xdg.html. In particular, this page includes pointers to slides, e.g. from the ESSLLI 2004 course by Ralph Debusmann and Denys Duchier: http://www.ps.uni-sb.de/~rade/talks.html.

XDG is a meta grammar formalism: it must be instantiated to yield a particular grammar formalism. An XDG instance can have any number of dimensions and on these dimensions, it can use any number of principles which stipulate the well-formedness conditions of an analysis. An XDG grammar consists of two parts:

1. a specification of the used XDG instance
2. a lexicon

In the XDK, grammars are written as XDK grammar files. Grammar files include both 1. and 2., i.e. the specification of the particular XDG instance used, and a lexicon.

The XDK provides the following:

• compilers for grammar files in various grammar file input languages
• the solver for XDG
• output functors to visualize the solutions of the solver
• the principle compiler Principle Writer (PrincipleWriter) for automatic compilation of principles into Mozart/Oz constraint functors
• executable programs exposing the functionality of the system:
  • graphical user interface (xdk)
  • standalone grammar file compiler (xdkc)
  • standalone grammar file converter (xdkconv)
  • standalone solver (xdks)
• various useful shell-scripts
• a number of handcrafted example grammars
• a grammar generator to generate XDG grammars from the TAG grammar developed in the XTAG project

The structure of this manual is as follows. Installation explains how to install the XDK. Compiler explains how to write grammar files in one of the various grammar file input languages. Grammars introduces the example grammars provided with the XDK. XTAG describes the XTAG grammar generator which generates XDG grammars from the TAG grammar developed in the XTAG project. In Solver, we explain the core of the XDK, i.e. the constraint-based solver. Oracles is about oracles to guide the search for solutions. Outputs explains the various available outputs. PrincipleWriter introduces the principle compiler, which can be used to extend the principle library. In Programs, we explain the executable programs provided by the XDK. Debug illustrates how XDG grammars can be debugged. References contains pointers to relevant papers, and Concept index is the concept index of this document.

Throughout this manual, sections labeled “developers only” contain information useful only for people who wish to understand the inner workings of the XDK. Here, in Directories, we describe the directory structure of the XDK. In Exceptions we specify the standard format for exceptions throughout the system. In Variable names, we describe the variable name conventions.