Partial hack for prefix inflection

This is a description of a partial hack for dealing with prefix inflection (see prefixes and infixes). Essentially it re-uses as much as possible components that we already have, although requires one more component, a pretagger module.

The first dictionary would be written in the normal manner, the second dictionary would be auto-generated from the first by means of lt-expand output coupled with the pretagger output.

Note: This is basically a hack on Mikel's suggestion #1 on the prefixes and infixes page.

One of the advantages of this system is that it is that the "normalisation" scheme (dictionary 2) can be generated from the dictionary + the pretagger and doesn't need to be hand-coded. Disadvantages are that it adds another layer, and probably misses a lot of nuances (e.g. multiwords, etc.).

Pipeline

$ echo "watu mtu" | lt-proc sw.automorf.bin 
^watu/m<pl>tu<n>$ ^mtu/m<sg>tu<n>$
$ echo "watu mtu" | lt-proc sw.automorf.bin  | pretagger.py
^watu/mtu<n><pl>$ ^mtu/mtu<n><sg>$
$ echo "watu mtu" | lt-proc sw.automorf.bin  | pretagger.py | apertium-tagger -g sw.prob 
^mtu<n><pl>$ ^mtu<n><sg>$
$ echo "watu mtu" | lt-proc sw.automorf.bin  | pretagger.py | apertium-tagger -g sw.prob  | lt-proc -g sw.automangle.bin 
m<pl>tu<n> m<sg>tu<n>

Then add the missing '^' and '$':

$ echo "^m<pl>tu<n>$ ^m<sg>tu<n>$" | lt-proc -g sw.autogen.bin 
watu mtu

Analysis

$ echo "watu" | lt-proc sw.automorf.bin
^watu/m<pl>tu<n>$

This would then be passed through the pretagger which would re-order the output thus:

^watu/mtu<n><pl>$

Basically just shunting all the tags to the end. This is now ready to be passed to the tagger.

Generation

Slightly more complicated. Out of final stage transfer you get:

^mtu<n><pl>$

This is then passed through the dictionary 2:

$ echo "^mtu<n><pl>$" | lt-proc -g sw.automangle.bin 
m<pl>tu<n>

Note: obviously we're missing the '^' and '$' here, but thats fairly straightforward to add.

Then it is passed through dictionary 1 in generation mode:

$ echo "^m<pl>tu<n>$" | lt-proc -g sw.autogen.bin
watu

Dictionaries

Dictionary 1 (sw-1.dix)

Compile

$ lt-comp lr sw.dix sw.automorf.bin
$ lt-comp rl sw.dix sw.autogen.bin

<dictionary>
  <alphabet>abcdefghijklmnopqrstuvwxyz</alphabet>
  <sdefs>
    <sdef n="n"/>
    <sdef n="sg"/>
    <sdef n="pl"/>
  </sdefs>
  <pardefs>
    <pardef n="C__1_2__n">
      <e><p><l>m</l><r>m<s n="sg"/></r></p></e>
      <e><p><l>wa</l><r>m<s n="pl"/></r></p></e>
    </pardef>

    <pardef n="mtu__n">
      <e><p><l/><r><s n="n"/></r></p></e>
    </pardef>
  </pardefs>
  <section id="main" type="standard">
    <e lm="mtu"><par n="C__1_2__n"/><i>tu</i><par n="mtu__n"/></e>
  </section>
</dictionary>

Dictionary 2 (sw-2.dix)

Compile

$ lt-comp lr sw-2.dix sw.automangle.bin

<dictionary>
  <alphabet>abcdefghijklmnopqrstuvwxyz</alphabet>
  <sdefs>
    <sdef n="n"/>
    <sdef n="sg"/>
    <sdef n="pl"/>
  </sdefs>

  <section id="main" type="standard">
    <e>
      <p>
        <l>mtu<s n="n"/><s n="sg"/></l>
	<r>m<s n="sg"/>tu<s n="n"/></r>
      </p>
    </e>
    <e>
      <p>
        <l>mtu<s n="n"/><s n="pl"/></l>
	<r>m<s n="pl"/>tu<s n="n"/></r>
      </p>
    </e>
  </section>
</dictionary>

Pretagger

A very rough 5 minute proof-of-concept:

#!/usr/bin/python
# coding=utf-8
# -*- encoding: utf-8 -*-

import sys, codecs, copy;
sys.stdout = codecs.getwriter('utf-8')(sys.stdout);
sys.stderr = codecs.getwriter('utf-8')(sys.stderr);

form = '';
tag = '';
tags = [];
lemma = '';

reading = '';

def pop_tags(tags, out): #{
	if len(tags) < 1: #{
		return out;
	#}
	out = out + tags.pop();
	return pop_tags(tags, out);
#}

def pull_tags(tags, out): #{
	for tag in tags: #{
		out = out + tag;
	#}
	return out;
#}

for char in sys.stdin.read().decode('utf-8'): #{
	if char == '^': #{
		sys.stdout.write(char);
		reading = 'form';
		continue;
	#}
	if char == '/': #{
		reading = 'lemma';

		if len(form) < 1 and len(lemma) > 1: #{
			sys.stdout.write(lemma + pop_tags(tags, ''));
			lemma = '';
			tags = [];
		#}

		sys.stdout.write(form);
		sys.stdout.write(char);
		form = '';
		continue;
	#}
	if char == '#': #{
		reading = 'pass';

		if len(form) < 1 and len(lemma) > 1: #{
			sys.stdout.write(lemma + pop_tags(tags, ''));
			form = '';
			lemma = '';
			tags = [];
		#}

		sys.stdout.write(char);
		continue;
	#}
	if char == '+': #{
		reading = 'pass';

		if len(form) < 1 and len(lemma) > 1: #{
			sys.stdout.write(lemma + pull_tags(tags, ''));
			form = '';
			lemma = '';
			tags = [];
		#}

		sys.stdout.write(char);
		continue;
	#}
	if char == '<' and reading is not 'pass': #{
		tag = '';
		reading = 'tag';
	#}
	if char == '>' and reading is not 'pass': #{
		tag = tag + char;
		tags.append(tag);
		reading = 'lemma';
		continue;
	#}
	if char == '$': #{
		if len(form) < 1 and len(lemma) > 1: #{
			sys.stdout.write(lemma + pop_tags(tags, ''));
			reading = 'lemma';
		#}
		tags = [];
		form = '';
		lemma = '';
		sys.stdout.write(char);
		reading = 'pass';
		continue;
	#}

	if reading == 'form': #{
		form = form + char;	
		continue;
	#}
	if reading == 'lemma': #{
		lemma = lemma + char;
		continue;
	#}
	if reading == 'tag': #{
		tag = tag + char;
		continue;
	#}
	if reading == 'pass': #{
		sys.stdout.write(char);
		continue;
	#}
#}