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Lttoolbox (français)

lttoolbox is a toolbox for lexical processing, morphological analysis and generation of words. Analysis is the process of splitting a word (e.g. cats) into its lemma 'cat' and the grammatical information <n><pl>. Generation is the opposite process.

The package is split into three programs, lt-comp, the compiler, lt-proc, the processor, and lt-expand, which generates all possible mappings between surface forms and lexical forms in the dictionary.


See Installation.


Main article: Monodix basics

Morphological analyser specification files, or morphological dictionaries may be found in all of our language pair packages, from the incubator, or you may elect to create your own (more instructions at the page Monodix basics). You can also check out our list of dictionaries, which has statistics on names, locations and number of entries of each of the dictionaries.



See also: Compiling dictionaries

Compilation into the binary format is achieved by means of the lt-comp program. You can compile a given .dix from left to right (LR), or from right to left (RL). Compiling LR usually creates an analyser, compiling RL usually creates a generator.[1]


Compile the dictionary in a left-to-right manner into the binary ca.bin.

$ lt-comp lr ca.bin


There are two main modes of use for the processor (lt-proc), analysis (which is the default mode) and generation. Analysis converts surface forms into the set of possible lexical forms, while generation converts a lexical form into the corresponding surface form.

See also: Using an lttoolbox dictionary


After compiling the file left-to-right into ca.morf.bin, we can analyse Catalan:

$ echo "prova" | lt-proc ca.morf.bin



And compiling it right-to-left, we can generate:

$ echo "^prova<n><f><pl>$"  | lt-proc -g ca.gen.bin



Sometimes you want to be able to see the complete output of the dictionary — i.e., all of the mappings between lexical and surface forms. For this you can use the lt-expand tool. This output is often useful in finding bugs in the assignment of paradigms, etc.


Here are the first ten lines that are produced as output from the command to expand the Catalan dictionary in the apertium-es-ca pair. (At last count, the total length of the output was over 2.3 million lines.)

$ lt-expand 



    <sdef n="n"/>
    <sdef n="sg"/>
    <sdef n="pl"/>

  <section id="main" type="standard">
    <e><p><l>beer</l><r>beer<s n="n"/><s n="sg"/></r></p></e>
    <e><p><l>beers</l><r>beer<s n="n"/><s n="pl"/></r></p></e>

$ lt-comp lr /tmp/test.dix /tmp/test.bin
main@standard 8 8

$ lt-print /tmp/test.bin 
0	1	b	b	
1	2	e	e	
2	3	e	e	
3	4	r	r	
4	5	ε	<n>	
4	6	s	<n>	
5	7	ε	<sg>	
6	7	ε	<pl>	


Empty left side

If you get a message like:

Error: Invalid dictionary (hint: the left side of an entry is empty)

Try searching for empty left sides in your dictionary by using lt-expand and grep. For example, in the Icelandic dictionary,

$ lt-expand  | grep ^:

The empty left side will look something like:

          <r>kunna<s n="vblex"/><s n="imp"/><s n="p2"/><s n="pl"/></r>

It is not possible to have an empty left side in a paradigm if you have no invariant (<i>) section in the main section entry, e.g.

    <e lm="kunna"><i></i><par n="/kunna__vblex"/></e>

This means you should look for the "kunna" verb; where the left side is empty, you should either put something there or add something to the invariant section.

Empty left side II

If you get a message like:

Error: Invalid dictionary (hint: the left side of an entry is empty)

and grep doesn't find anything, then look in your pardefs. You probably have something like:

   <pardef n="na__S">

Add a dummy entry to make it work:

   <pardef n="na__S">
      <e>       <p><l>NON_ANALYSIS</l>          <r>DUE_TO_LT_PROC_HANG</r></p></e>

(This one seems like a bug: )

Entry beginning with whitespace

If you get a message like:

Error: Invalid dictionary (hint: entry beginning with whitespace)
Error: Input is null - nothing to parse!

The problem may be in a monolingual dictionary. You may have an entry like:

<e lm="Pilato"><i> Pilato</i><par n="Juan__np"/></e>


<e lm="Pilato"><i><b/>Pilato</i><par n="Juan__np"/></e>

Or also in the bilingual dictionary, for instance:

<e>       <p><l>cave<s n="n"/><s n="f"/></l>      <r> soterrani<s n="n"/><s n="m"/></r></p></e>
lt-expand/lt-proc on different machines gives different output for metadix

When trying to e.g. lt-expand dictionaries with the alt-attribute (which is not valid XML according to the dix DTD), some machines might give lines with the attribute and some might skip them. If lttoolbox was compiled against an older version of libxml2, you will get the lines included, with newer libxml2 they will be skipped. To ensure you get the same output for lt-expand/lt-proc on all machines, you might have to do a "make clean; ./ && make && make install" (after ensuring your system is up-to-date).

(In any case, metadix should not be expanded/compiled directly, run the commands on the files that have been through xsltproc, typically in .deps)


$ yes word | head -10000000 > /tmp/foo

$ head /tmp/foo

$ wc -l /tmp/foo
1000000 /tmp/foo

$ time cat /tmp/foo | lt-proc en-ca.automorf.bin >/dev/null

real	0m17.606s
user	0m17.281s
sys	0m0.036s

58,823 words / second

Using as a library[edit]

See Lttoolbox API for how to analyse and generate (single) words with lttoolbox from C++ or Python.

See also Daemon#Using_as_libraries on how to redirect the FILE streams for longer translation requests.

Wishlist / TODO[edit]

Postgenerator alarms[edit]

Many monodixes handle postgenerator alarms <a/> explicitly in each entry. As a result, left-to-right entries have to be separated from right-to-left entries. However, it could be much easier to write a paradigm like

<pardef n="wiggle">
    <e r="LR">
    <e r="RL">

and then invoke it in entries as follows

<e lm="a">
   <par n="wiggle"/>
   </par n="a__pr"/>

This suggests that perhaps it would be even easier to change the meaning of <a/> so that it only works right to left, or perhaps endow it with the r attribute as follows: <a r="RL"/>.

See also[edit]


  1. In all current linguistic packages, the left-to-right direction of compilation is analysis, whereas the right-to-left direction is generation. This is not, however, a software restriction.