TGrep2

Introduction

TGrep2 is mostly backward compatible with tgrep, but it also offers a number of new features, including the following major enhancements:

• Rather than simply having a set of required relationships and a set of prohibited relationships, nodes can have full boolean expressions of relationships to other nodes.
• Nodes can be given unique labels and may then be referred to by those labels in the pattern specification or in selecting trees for printing.
• Patterns are no longer restricted to simple tree architectures. The use of node labels and segmented patterns allows links in a pattern to form back-edges as well, permitting cycles of links.
• Customizable output formats allow a variety of information to be reported in a flexible manner.
• Multiple search patterns may be specified and one can retrieve the first subtree matching any pattern, the first subtree matching each pattern, or all subtrees matching all patterns.
• Subtrees can be reported using a code rather than by printing the whole structure. The trees themselves can later be retrieved using the codes.
• A variety of new links have been added and the immediately-precedes link now has a more conventional meaning.
• TGrep2 corpus files are substantially smaller than tgrep corpora.

Manual

Installing TGrep2

If the tgrep2 executable does not work on your machine, you will need to compile your own. This involves two steps:

First you must compile the libdrutils.a library. To do this, go to this web page and follow the instructions.

Next, assuming you have already unpacked the tgrep2 tar file, you should edit the first line of the Makefile to point to the location of the DRUtils header files (drutils.h).

Now run make and with any luck it will compile nicely. There is no built-in mechanism for installing it someplace special on your machine. But it's only a single, stand-alone executable, so you should be able to handle that yourself.

Version Notes

• Added a mode for working with Combinatory Categorial Grammar (CCG).
• Converted to the GNU General Public License.

• Fixed a bug when using %Na without %Nb. Thanks to Neal Snider for finding this one.

• ?

• Fixed a parsing bug in segmented patterns introduced in 1.08.

• Added the %k, %d, %y, and %z tree-printing styles to report the length of a subtree in terminals symbols, its maximum depth, and the terminal index of the first and last terminals in the tree.

• The -f and -a options are now independent and can be combined to report, without duplication, subtrees that match one or more patterns.

• Fixed a potential crash when reading badly formatted subtree code files.
• Thanks to Eric Joanis for fixing a potential crash in reading commented files.

• Patterns of the following form are now all well-formed and equivalent:
  A < B < C
  (A < B < C)
  ((A < B) < C)
  ((((A) < B)) < C)

• Fixed some problems with subtree copies. Copied subtrees can no longer have any back edges.
• If a pattern segment is empty, it will now be ignored.

• Fixed a bug introduced in 1.06.

• Macros can now be defined and used to simplify pattern specification.
• Multiple patterns or pattern files can be given on the command-line.
• Optional links have been added, thanks to Eric Joanis, to allow certain features of a tree to be reported if they occur, without preventing a match when they don't.
• A bug was fixed in which nodes could be printed out even when a match did not occur below a disjoined or optional link.

• Added the = operator, which means that the pattern on the right must match the node matched by the one on the left. This has various uses, one of which is the fact that it can be combined with ! to rule out certain patterns. For example, this matches any node starting with NP, except for NP-TMP: (/^NP/ != NP-TMP)
• You can also append = to any other link to mean that the identity match is allowed (in addition to the standard meaning of the link). For example, A >>= B means B dominates A or is equal to A.
• I added support for reading and writing bzip2 files. Thanks to Eric Joanis for writing the first implementation of this.
• Fixed a bug that caused extra newlines in -l (long format) output mode.

• Added the -i flag, which causes node-name matching to be case-insensitive.
• Added the ability to complement node-name matching by preceding the pattern with !. !DT|RB now matches all nodes whose name is not DT nor RB.
• Note that version 1.04 of the manual supercedes, 1.3, which was named incorrectly.

• Added support for sentence-level comments. When compiling a corpus, comments can appear in the input provided the line starts with a #. The -C option causes the comments to be stored in the corpus file or printed when a match is made while searching. The %c field allows comments to be printed in formatted output.
• Corpora can now be constructed for trees with a branching factor higher than 255, using the -K flag.
• The new link types <: >: <<: and >>: have been added to match only children or parents of only children.
• If a labeled node is printed in formatted output and the label is not bound to any node, it will print "<none>" rather than generate an error.

• Added the -u option and %u... formatting flag to allow the printing of just the top symbol in a subtree.
• Removed an unaligned memory access that caused problems under Solaris.

Acknowledgements

• Thanks to Eric Joanis for suggesting the ability to handle comments and more than 255 children per node and for writing the first implementation of those features.

Copyright

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