The Grammar Development Environment

Working with and developing a large grammar is a challenging process, and the importance of having good visualization tools cannot be over-emphasized. Currently the XTAG system has X-windows based tools for viewing and updating the morphological and syntactic databases ([#!karp92!#,#!EgediMartin94!#]). These are available in both ASCII and binary-encoded database format. The ASCII format is well-suited for various UNIX utilities (awk, sed, grep) while the database format is used for fast access during program execution. However even the ASCII formatted representation is not well-suited for human readability. An X-windows interface for the databases allows users to easily examine them. Searching for specific information on certain fields of the syntactic database is also available. Also, the interface allows a user to insert, delete and update any information in the databases. Figure 3.3(a) shows the interface for the morphology database and Figure 3.3(b) shows the interface for the syntactic database.

  

Figure 3.3: Interfaces to the database maintenance tools

(a) Morphology database	(b) Syntactic database

XTAG also has a parsing and grammar development interface ([#!PSJ92!#]). This interface includes a tree editor, the ability to vary parameters in the parser, work with multiple grammars and/or parsers, and use metarules for more efficient tree editing and construction ([#!becker94!#]). The interface is shown in Figure 3.4. It has the following features:

• Menu-based facility for creating and modifying tree files and loading grammar files.
• User controlled parser parameters, including the root category (main S, embedded S, NP, etc.), and the use of the tagger (on/off/retry on failure).
• Storage/retrieval facilities for elementary and parsed trees.
• The production of postscript files corresponding to elementary and parsed trees.
• Graphical displays of tree and feature data structures, including a scroll `web' for large tree structures.
• Mouse-based tree editor for creating and modifying trees and feature structures.
• Hand combination of trees by adjunction or substitution for use in diagnosing grammar problems.
• Metarule tool for automatic aid to the generation of trees by using tree-based transformation rules

  

Figure 3.4: Interface to the XTAG system