Free Swedish Word Lists or Hackers’ BLARK Viggo Kann KTH, Stockholm GSLT meeting January 26, 2008

What is a free language resource? Anyone can use it in an application Anyone can study it and modify it Anyone can take a copy of it Anyone can improve it, release the improvements to the public, so that the whole community benefits (based on four freedoms of free software, Richard Stallman)

Strong free software culture GNU project FSF – Free Software Foundation GPL – GNU General Public License OSI – Open Software Initiative Linux, TeX, Emacs, GCC, MySQL, PHP, Java, Python, Firefox

First meeting of the Free Swedish Words group at KTH January persons from around Sweden Lars Aronsson: project Runeberg and Swedish Wikipedia (Wiktionary) Lars Törnquist and Sven Lange: Swedish thesaurus built on Bring (1930) Christian Mattson: Lexin dictionaries

Niklas Johansson: Spelling error detection and correction in OpenOffice Göran Andersson: DSSO – The large Swedish word list Viggo Kann: Stava, Granskatagger, Synlex, Tvärslå Nordic dictionary Per Starrbäck, Leif-Jöran Olsson, Tomas Padron-McCarthy, Erik Geijer

Plans for more free words Swedish synonyms in OpenOffice (Niklas) Extending DSSO with synonyms, associations etc (Göran) Building a free Swedish-English dictionary (Viggo) Testing Swedish grammar checking in Languagetool/OpenOffice (Viggo&Niklas)

Typical ways to construct a resource …if you are a language technologist: Get funding Use resources that are free to use for researchers Hire linguists to do the heavy jobs …if you are a free software hacker: Use other free resources Collect data from lots of people using e.g. a wiki or a web form

Example: Synlex Construct a Swedish dictionary of synonyms as a list of synonymous pairs I don’t want to work a lot I don’t want to pay anyone to work The resulting list should become free

Ideas Automatically construct a large set of word pairs that might be synonyms Use ten thousands of people, who are each willing to make a small contribution without payment, to check the word pairs

More ideas Use the Lexin on-line Swedish-English dictionary web site, that had 9 millions (now 25 M) of lookups each month Users visit Lexin to translate words, and are thus probably motivated to help me Each time a user makes a lookup, give her the opportunity to decide whether two words are synonyms or not

My plan 1. Construct lots of possible synonyms 2. Sort out bad synonym pairs automatically 3. Ask lots of users if the rest of the pairs are good synonyms 4. Analyze the gradings done by the users and decide which pairs to keep

Step 1: Construct lots of possible synonyms If we have access to a Swedish-English dictionary SE and an English-Swedish dictionary ES, try to translate each word to English and back again to Swedish {(w,v):  y: y  SE(w)  v  ES(y)} or {(w,v):  y: y  SE(w)  y  SE(v)} word pairs were generated

Step 2: Remove bad synonym pairs automatically Use RI (Random Indexing) [Kanerva, Kristoferson, Holst 2000] to measure the distance between words represented in a large vector space Keep pairs that have small enough distance in the vector space

Step 3: Ask lots of users if the rest of the pairs are good synonyms When a user has sent a word to the Lexin dictionary he receives the translation followed by a question like: Are 'spread' and 'lengthen' synonyms? Answer using a scale from 0 to 5 where 0 means 'I don’t agree' and 5 means 'I do fully agree', or answer 'I don’t know'

Step 4: Analyzing the gradings done by the users 1.2 millions gradings were made in less than 2 months Grading statistics were analyzed on several occasions Some users sent comments

More and more interesting gradings as time goes by

Distribution of mean gradings of word pairs

Some statistics (January 2008) 2.8 M user gradings done pairs (graded ≥ 2) in dictionary pairs suggested by users unique pairs suggested of them have been accepted

Example: Synonyms to klass (class) 5: rang (grade) rank (rank) slag (kind) 4: kategori (category) stånd (social class) årskurs (grade) 3: fack (sphere) grad (degree) grupp (group) kvalitet (quality) nivå (level) 3: sort (sort) standard (standard) stil (style) 2: skikt (layer) storleksordning (magnitude) typ (type) 1: poäng (point) stadga (stability) 0: uppdrag (mission) utbilda (educate)

How to prevent abuse? Many gradings of a word pair are needed before it’s considered to be good The pair to be graded is randomly picked from a very large list Word pairs suggested by users are spell checked before they are added to the very large list

People's definition of synonymy Exact meaning of 'synonym' wasn’t defined Users will grade using their intuitive understanding of the concept of synonymy and the words in the pair The produced dictionary will use the people's own definition of synonymy Hopefully this is exactly what they want!

Links The large Swedish word list Spell checker lexin.nada.kth.se/synlex.html synonyms lexin.nada.kth.se/synlex.html sv.wiktionary.org word dictionary sv.wiktionary.org Hyperlexicon