View source for Starting a new language with lttoolbox

{{TOCD}}
:''For information on how to install lttoolbox, see [[lttoolbox]] and [[minimal installation from SVN]]''

This page is going to describe how to start a new language with [[lttoolbox]]. As lttoolbox is not really suited to agglutinative languages, or languages with complex and regular morphophonology (see [[starting a new language with HFST]]), we're going to work on one with simpler and less regular morphology.

==Preliminaries==

A morphological transducer in lttoolbox has typically one file, a <code>.dix</code> file. This defines both how morphemes in the language are joined together, ''morphotactics'', and how changes happen when these morphemes are joined together, ''morphographemics'' (or ''morphophonology''). For example, 

* Morphotactics: wolf<n><pl> → wolf + s 
* Morphographemics: wolf + s → wolves 

These two phenomena are treated in the same file.

==The language==

The language we will be modelling is Upper Sorbian, a Slavic language spoken in Germany. There is a limited grammar available in English [http://serbscina.w.interia.pl/iso/eindex.htm here] and that is what we will be basing our analysis on. The part of speech we're going to look at for this small tutorial is nouns. Nouns in Upper Sorbian have seven cases (nominative, genitive, dative, accusative, locative, instrumental, vocative), three numbers (singular, dual, plural) and three genders (masculine, feminine, neuter). Like other Slavic languages, the category of animacy is distinguished in the masculine.

===Paradigms===

Here we give four example paradigms, these will form the basis of our implementation.

;Masculine animate (''nan'' "father")

{|class=wikitable
!                  !! Singular     !! Dual          !! Plural
|-
| Nominative       || nan          || nan'''aj'''   || nan'''ojo'''
|-
| Genitive         || nan'''a'''   || nan'''ow'''   || nan'''ow'''
|-
| Dative           || nan'''ej'''  || nan'''omaj''' || nan'''am'''
|-
| Accusative       || nan'''a'''   || nan'''ow'''   || nan'''ow'''
|- 
| Instrumental     || nan'''om'''  || nan'''omaj''' || nan'''ami'''
|-
| Locative         || nan'''je'''  || nan'''omaj''' || nan'''ach'''
|- 
| Vocative         || nan'''o'''!  || nan'''aj'''!  || nan'''ojo'''!
|-
|}

;Masculine inanimate (''hrěch'' "sin")

The differences from the masculine animate paradigm are indicated in blue.

{|class=wikitable
!                  !! Singular     !! Dual          !! Plural
|-
| Nominative       || hrěch          || hrěch'''aj'''   || <span style="background-color:#cceeff">hrěch'''i'''</span>
|-
| Genitive         || hrěch'''a'''   || hrěch'''ow'''   || hrěch'''ow'''
|-
| Dative           || hrěch'''ej'''  || hrěch'''omaj''' || hrěch'''am'''
|-
| Accusative       || <span style="background-color:#cceeff">hrěch</span>          || <span style="background-color:#cceeff">hrěch'''aj'''</span>   || <span style="background-color:#cceeff">hrěch'''i'''</span>
|- 
| Instrumental     || hrěch'''om'''  || hrěch'''omaj''' || hrěch'''ami'''
|-
| Locative         || <span style="background-color:#cceeff">hrěch'''u'''</span>   || hrěch'''omaj''' || hrěch'''ach'''
|- 
| Vocative         || hrěch'''o'''!  || hrěch'''aj'''!  || <span style="background-color:#cceeff">hrěch'''i'''</span>!
|-
|}

;Feminine (''wróna'' "crow")

The parts in common with the masculine paradigms are highlighted in green.

{|class=wikitable
!                  !! Singular     !! Dual          !! Plural
|-
| Nominative       || wrón'''a'''   || wrón'''je'''   || wrón'''y'''
|-
| Genitive         || wrón'''u'''   || <span style="background-color:#ccffcc">wrón'''ow'''</span>   || <span style="background-color:#ccffcc">wróna'''ow'''</span>
|-
| Dative           || wrón'''je'''  || <span style="background-color:#ccffcc">wrón'''omaj'''</span> || <span style="background-color:#ccffcc">wróna'''am'''</span>
|-
| Accusative       || wrón'''u'''   || wrón'''je'''   || wrón'''y'''
|- 
| Instrumental     || wrón'''u'''   || <span style="background-color:#ccffcc">wrón'''omaj'''</span> || <span style="background-color:#ccffcc">wróna'''ami'''</span>
|-
| Locative         || wrón'''je'''  || <span style="background-color:#ccffcc">wrón'''omaj'''</span> || <span style="background-color:#ccffcc">wróna'''ach'''</span>
|- 
| Vocative         || wrón'''a'''!  || wrón'''je'''!  || wrón'''u'''!
|-
|}

;Neuter (''trašidło'' "monster")

Forms in common with both the masculine and feminine paradigms are highlighted in red.

{|class=wikitable
!                  !! Singular     !! Dual          !! Plural
|-
| Nominative       || trašidł'''o'''   || trašidł'''e'''   || trašidł'''a'''
|-
| Genitive         || trašidł'''a'''   || <span style="background-color:#ffcccc">trašidł'''ow'''</span>   || <span style="background-color:#ffcccc">trašidł'''ow'''</span>
|-
| Dative           || trašidł'''u'''  || <span style="background-color:#ffcccc">trašidł'''omaj'''</span> || <span style="background-color:#ffcccc">trašidł'''am'''</span>
|-
| Accusative       || trašidł'''o'''   || trašidł'''e'''   || trašidł'''a'''
|- 
| Instrumental     || trašidł'''om'''  || <span style="background-color:#ffcccc">trašidł'''omaj'''</span> || <span style="background-color:#ffcccc">trašidł'''ami'''</span>
|-
| Locative         || trašidł'''e'''  || <span style="background-color:#ffcccc">trašidł'''omaj'''</span> || <span style="background-color:#ffcccc">trašidł'''ach'''</span>
|- 
| Vocative         || trašidł'''o'''!  || trašidł'''e'''!  || trašidł'''a'''!
|-
|}

==Lexicon==

So, given the description above, how do we start to write a morphological description in [[lttoolbox]] ? Well, first we start with our filename, <code>hsb.dix</code>, so open up a text editor and save an empty document with that name.

===The basics===

;The skeleton

The basic skeleton of an lttoolbox dictionary looks like the following:

<pre>

<dictionary>
  <alphabet>abc...</alphabet>
  <sdefs>
    ...
  </sdefs>
  <pardefs>
    ...
  </pardefs>
  <section id="main" type="standard">
    ...
  </section>
</dictionary>

</pre>

So type this up into the file, this gives the outline of our the main parts of our morphology: the alphabet (used for tokenisation) the symbols (or ''tags'') which give us useful mnemonics for grammatical features, the {{tag|pardefs}} section, which gives our inflectional paradigms, and finally the main section of the file which contains our lexical items.

;Symbol (tag) definitions

The first thing we'll start with is the list of symbols which are going to encode our grammatical features (part-of-speech, gender, number, case). The page [[list of symbols]] gives some common tags in Apertium. Generally we try and keep features which are the same between languages tagged the same, thus for example the tag for "nominative" will be {{tag|nom}}, regardless of if we are talking about Romanian, Serbo-Croatian, Icelandic or Albanian. Symbols are defined in the {{tag|sdefs}} section with {{tag|sdef}} elements,

<pre>

<sdefs>
  <sdef n="n"     c="Noun"/>

  <sdef n="ma"    c="Masculine (animate)"/>
  <sdef n="mi"    c="Masculine (inanimate)"/>
  <sdef n="nt"    c="Neuter"/>
  <sdef n="f"     c="Feminine"/>

  <sdef n="sg"    c="Singular"/>
  <sdef n="du"    c="Dual"/>
  <sdef n="pl"    c="Plural"/>

  <sdef n="nom"   c="Nominative"/>
  <sdef n="gen"   c="Genitive"/>
  <sdef n="dat"   c="Dative"/>
  <sdef n="acc"   c="Accusative"/>
  <sdef n="ins"   c="Instrumental"/>
  <sdef n="loc"   c="Locative"/>
  <sdef n="voc"   c="Vocative"/>
</sdefs>

</pre>

The <code>c</code> stands for comment and is optional, but quite convenient if you have a lot of tags and want a quick reference to what they mean!

;Our first paradigm!

After we've defined our symbols then the next thing to do is to write our first paradigm... We'll start with the paradigm for ''nan'' "father". There is a convention in Apertium that each major paradigm identifier is made up of at least the name of one of an exemplar word, and its part of speech. In this case we will also add the gender.

A paradigm is made up of a series of entries, each entry has a ''pair'' ({{tag|p}}), which in turn has a ''left'' side ({{tag|l}}) and a ''right'' side ({{tag|r}}). Normally, the [[surface form]] is found on the left and the [[lexical form]] on the right.

We can use the symbols we defined earlier with {{tag|sdef}} tags by calling them with the {{tag|s}} element.

<pre>
<pardefs>
  <pardef n="nan__n_ma">
    <e><p><l></l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="nom"/></r></p></e>
    <e><p><l>a</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="gen"/></r></p></e>
    <e><p><l>ej</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="dat"/></r></p></e>
    <e><p><l>a</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="acc"/></r></p></e>
    <e><p><l>om</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="ins"/></r></p></e>
    <e><p><l>je</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="loc"/></r></p></e>
    <e><p><l>o</l><r><s n="n"/><s n="ma"/><s n="sg"/><s n="voc"/></r></p></e>

    <e><p><l>aj</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="nom"/></r></p></e>
    <e><p><l>ow</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="gen"/></r></p></e>
    <e><p><l>omaj</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="dat"/></r></p></e>
    <e><p><l>ow</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="acc"/></r></p></e>
    <e><p><l>omaj</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="ins"/></r></p></e>
    <e><p><l>omaj</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="loc"/></r></p></e>
    <e><p><l>aj</l><r><s n="n"/><s n="ma"/><s n="du"/><s n="voc"/></r></p></e>

    <e><p><l>ojo</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="nom"/></r></p></e>
    <e><p><l>ow</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="gen"/></r></p></e>
    <e><p><l>am</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="dat"/></r></p></e>
    <e><p><l>ow</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="acc"/></r></p></e>
    <e><p><l>ami</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="ins"/></r></p></e>
    <e><p><l>ach</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="loc"/></r></p></e>
    <e><p><l>ojo</l><r><s n="n"/><s n="ma"/><s n="pl"/><s n="voc"/></r></p></e>
  </pardef>
</pardefs>
</pre>

;Using the paradigm

Now that we've defined a paradigm we can add a word that uses it. The obvious choice is "nan", being as that is the name of the paradigm,

<pre>

  <section id="main" type="standard">
    <e lm="nan"><i>nan</i><par n="nan__n_ma"/></e>    
  </section>

</pre>

The {{tag|e}} element is the same as in the paradigm, but in the case of lexical entries (as opposed to morphological entries), it commonly contains the attribute <code>lm</code> "lemma". The {{tag|i}} tag stands for "invariant" and means that the left side is the same as the right side.

So, by this point we should have a whole dictionary with a single word in it. Save the file!

===Compiling===

Once you've saved the file, you can go to the command line and try and validate it, presuming the file is called <code>hsb.dix</code>, then the following will check it against the definition:

<pre>
$ apertium-validate-dictionary hsb.dix 
</pre>

If the dictionary is valid you should get no output.

This is a major benefit over related software (e.g. [[HFST]]), if you leave out a symbol definition, then you will get an angry message from the validation script such as the following:

<pre>
$ apertium-validate-dictionary hsb.dix 
hsb.dix:25: element s: validity error : IDREF attribute n references an unknown ID "nom"
hsb.dix:33: element s: validity error : IDREF attribute n references an unknown ID "nom"
hsb.dix:41: element s: validity error : IDREF attribute n references an unknown ID "nom"
Document hsb.dix does not validate against /home/fran/local/share/apertium/dix.dtd
</pre>

In this case, it's best to go back and check that all your symbols are defined!

So, assuming that our dictionary is valid, we can move to the next step and compile it,

<pre>
$ lt-comp lr hsb.dix hsb-mor.bin
main@standard 29 45

$ lt-comp rl hsb.dix hsb-gen.bin
main@standard 29 45
</pre>

The <code>lr</code> and <code>rl</code> in the compilation command stand for "left to right" and "right to left" respectively. Presuming we have our surface form on the left, and our lexical form on the right, compiling <code>lr</code> will make a morphological analyser, and compiling <code>rl</code> will make a generator.

===Usage===
{{see-also|lttoolbox}}
We can then test them both as follows,

<pre>
$ echo "nanow" | lt-proc hsb-mor.bin 
^nanow/nan<n><ma><du><gen>/nan<n><ma><du><acc>/nan<n><ma><pl><gen>/nan<n><ma><pl><acc>$

$ echo "^nan<n><ma><pl><gen>$" | lt-proc -g hsb-gen.bin 
nanow
</pre>

===Paradigms===

==Analysis and generation==


==Troubleshooting==


==Notes==
<references/>

==Further reading==

==See also==

* [[Starting a new language with HFST]]

[[Category:Documentation]]