University of Sussex  8 Sep 2003

This directory contains software for morphological processing of English
as developed by Kevin Humphreys <[email protected]>, John Carroll
<[email protected]> and Guido Minnen.

Covers the English inflectional suffixes:

  -s     plural of nouns, 3rd person singular present of verbs
  -ed    past tense
  -en    past participle
  -ing   progressive of verbs

1. Usage
--------

  morpha [-a] [-c] [-t] [-u] [-f verbstem-file]

The commands operate as filters, reading from the standard input and
writing to the standard output.

They may be invoked with the following command-line options:

  -a Output affixes (morpha only).

  -c Preserve case distinctions wherever possible.

  -t Output part-of-speech tags if they are in the input.

  -u Indicate that the words in the input are not tagged with
     part-of-speech labels. N.B. This mode of use is not recommended
     since the resulting ambiguity in the input is likely to lead to
     incorrect output.

  -f By default, the commands attempt to read a file called
     'verbstem.list' in the user's current directory which is expected
     to contain a list of stems of verbs that undergo doubling of
     their final consonant, as occurs in British English spelling.
     This option allows the user to specify a different file of verb
     stems (for example if American English behaviour is required).
     If this option is specified then it must be the last one on
     the command-line.

See the file doc.txt for specifications of input and output formats,
and examples of usage.

2. Files
--------

  Makefile       makefile for compiling the flex sources; can be
                 used for compiling both flex descriptions by 
                 the command `make flex-description-file'
  README         this file
  doc.txt        specifications of input/output formats, and usage
                 examples
  minnen.pdf     pre-final PDF version of the NLE article by Minnen, 
                 Carroll and Pearce (2001)
  morpha.lex     flex description constituting the source of the 
                 morphological analyser 
  verbstem.list  list of verb stems that allow for consonant doubling
                 in British English 

3. Compilation
--------------

To recompile the morph tools, either type the following commands
(making sure that you use the 2.5.4a version of flex recompiled with
larger internal limits -- see below), or (more conveniently) use the
Makefile in this directory by typing `make morpha' or `make morphg'.

  flex -i -Cfe -8 -omorpha.yy.c ../enc/charclasses.flex morpha.lex
  gcc -o morpha morpha.yy.c

The included Makefile omits the
Flex options -Cfe -8, resulting in a reduction in binary file size
of two thirds (and a reduction in processing speed of around 20%).
These options also have to be left out and the option -Dinteractive
added to gcc (resulting in a further decrease in throughput) in order
to get the morph tools to return results immediately when used via
unix pipes inside other programs.

N.B. Recompiling the morph tools requires an adapted version of Flex.
The top-level Makefile downloads, patches and builds a suitable version.
The Flex source code is freely available from:

  http://sourceforge.net/project/showfiles.php?group_id=97492 > older releases

The Flex source should be changed to allow for more internal states by
increasing the definitions in flexdef.h of:

  #define JAMSTATE -32766 
  ... 
  #define MAXIMUM_MNS 31999
  ...
  #define BAD_SUBSCRIPT -32767

to:

  #define JAMSTATE -800000 
  ... 
  #define MAXIMUM_MNS 800000
  ...
  #define BAD_SUBSCRIPT -800000

and recompiling Flex. When recompiling the morph tools ensure that the
Makefile points to the new version of Flex.

4. Acknowledgements, copyrights etc.
------------------------------------

The exception lists were derived semi-automatically from WordNet 1.5,
and various other corpora and MRDs.

Many thanks to Tim Baldwin, Chris Brew, Bill Fisher, Gerald Gazdar,
Dale Gerdemann, Adam Kilgarriff and Ehud Reiter for suggested
improvements.

WordNet 1.5 Copyright 1995 by Princeton University.
All rights reseved.

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