Specification of Estonian and Czech Wordnets

Haldur Õim, Kadri Vider, Leho Paldre, Heili Orav, University of Tartu
Karel Pala, University of Brno

Deliverable 2D003 
EuroWordNet, LE4-8283

Identification number
	LE4-8283-2D-003
	
Type
	Document	
Title
	Specification of Estonian and Czech	
Status
	Final	
Deliverable
	2D003	
Work Package
	WP?	
Task
	T?.?	
Period covered
		
Date
		
Version
		
Number of pages
	18	
Authors
	Haldur Õim, Kadri Vider, Leho Paldre, Heili Orav, University of Tartu
Karel Pala, University of Brno	
WP/Task responsible	TAR	
Project contact point	 Piek Vossen
 Computer Linguistiek
 University of Amsterdam
 Spuistraat 134
 1012 VB Amsterdam
 The Netherlands
 tel.  +31 20 525 4669
 fax. +31 20 525 4429
 e-mail: Piek.Vossen@hum.uva.nl	
EC project officer	Ray Hudson	
Status
	Public	
Actual distribution
	Project Consortium
	
Supplementary notes
		
Key words	
	
Abstract	This document describes the local tools and resources used by TAR and BRN in creating, accordingly, the wordnets of Estonian and Czech, the procedures of selecting the primary sets of Base Concepts and the main problems encountered in translating the test samples  from EWN1 into Estonian and Czech.	
Status of the abstract
	Final	
Received on	
	
Recipient’s catalogue number		

Executive Summary

This document covers three topics in the creation of the wordnets for Estonian and Czech in the frames of EuroWordNet-2: local tools and resources that can be used in the process of creating the national wordnets, the process of selecting the primary sets of Base Concepts, and the main problems encountered in translating the test samples from EuroWordNet-1 (WordNet 1.5) database into Estonian and Czech, accordingly. 

For both languages there exist, in electronic form, several dictionaries and corpora  that can be used in the work, but still these resources are limited relative to those used for creating wordnets for English, Dutch, Italian and Spanish in EuroWordNet-1, so much work has to be done manually.

Both partners used procedures of selecting Base Concepts that are slightly different from those specified in EuroWordNet-1. These differences are mainly explained by the existing resources and tools that could be used in the task.

In the case of both languages a number of difficulties were encountered in translating the English concepts (synsets) from WordNet 1.5 into the expressions of Estonian or Czech. There are cases of simple lexical gaps, but there are also more basic discrepancies that derive from different lexicalization patterns used by these three languages.

Table of Contents

1.	Estonian Wordnet								6
1.1. Local resources and tools							6
1.1.1. Overview of local resources						6
1.1.1.1.	 Available monolingual resources					6
1.1.1.2.	 Available bilingual resources						7
1.2.	Overview of local tools and databases					7
1.3.	Procedure of the selection of Base Concepts for Estonian		8
1.4.	Some experiences and problems					9
2.	Czech Wordnet								10
2.1.	Tools and resources							10
2.1.1.	Overview of local tools						10
2.1.2.	Overview of local resources						11
2.2.	Selecting Czech Base Concepts					11
2.3.	Further work and problems						12
2.3.1.	Further work								12
2.3.2.	Problems with translation equivalents and gaps			13

1.	ESTONIAN WORDNET 

1.1.	Local resources and tools

The following tools and resources have been/will be used at TAR for EWN-2

1.1.1.	Overview of local resources

1.1.1.1.Available monolingual resources

1)	Eesti kirjakeele seletussõnaraamat, EKSS (Explanatory Dictionary of Estonian). Unfortunately, at the moment EKSS contains published materials only from A to R (though the work on the missing part is proceeding rapidly). And second, since work on EKSS-s electronic version has been carried out during a long period, its original markup is inconsistent and often defective. Thus we first had to convert it to a coherently coded form, so that it would be possible to automatically extract sense descriptions (glosses), examples etc.
At present EKSS contains:
-	50.890 entries (the number of entries is in fact much larger, since many compound word expressions, phraseologisms etc are merged in these main entries),
-	118.442 senses (including 103.525 senses for which sense descriptions are provided).

2)	Sünonüümisõnastik (Dictionary of Synonyms) by Asta Oim, available also in Internet (http://www.ibs.ee.estonian/syn/).
It contains about 10.000 synonym sets which include also multiword expressions and phraseologisms.

3)	Antonüümisõnastik (Dictionary of Antonyms) by Asta Oim, also available in Internet (http://www.ee/Anton/).
Contains 2.000 antonymous pairs where each member of a pair is actually a set of synonyms compiled largely on the basis of 2).

4)	Estonian Thesaurus for Microsoft Office ´97 compiled by Filosoft (http://www.filosoft.ee/thes_et/). It contains mainly information on synonyms and antonyms.
Number of synonym sets: 12.800 (including 3.400 multiword expressions);
number of synonym sets with antonyms: 3.800;
total number of words and expressions: 51.600.
The lexicon contains only lemmas, inflected words are included only when these are synonymous with words of some other part of speech.

5)	For working with Estonian lexical resources in Internet there is a new site called KeeleWeb (LinguaWeb), http://ee.www.ee/, where it is possible to make united queries over 5 different monolingual dictionaries.

6)	Eesti Kirjakeele Korpus, EKK (Corpus of Written Estonian). The internet version: http://www.cl.ut.ee/index_en.html; for its users there are also available tools for analysing corpus texts: morphological analyser, Estonian HTML speller, Concordance for Estonian etc.
Size of the Corpus: 1 million words, tagged according to TEI. Texts are selected from issues printed on 1980s and according to the classification of the Brown Corpus.

In addition to EKK there are (untagged) corpora compiled with the aim of enabling the study of the usage of Estonian in newspapers and in fiction at different periods:
-1960s (330.000 words),
-1950s (308.000 words),
-1930s (369.000 words),
-1890s (348.000 words).

Thirdly, there is BNS (=Baltic News Service) News Corpus (plain text), about 3 million words a year since 1996.

1.1.1.2. Available bilingual resources:

1)	Password – English Dictionary for Speakers of Estonian, Kernerman Semi-Bilingual Dictionaries (translated and published by TEA Publishers, 1995; the electronic version by Festart 1995).
It contains 25.000 headwords with sense descriptions in English, 36.000 translations into Estonian. It also includes index as Estonian-English Translation Dictionary.

2)	English-Estonian-English Dictionary, http://www.ibs.ee/dict/, Copyright by Marek Tiits 1994-95; Institute of Baltic Studies Copyright 1994; KINEX Ltd 1995 MT.
More than 17.000 entries.

Unfortunately, using dictionaries and other lexical resources available in internet, we can only make queries, but can’t handle them as complete resources or databases.

1.1.2.	Overview of local tools and databases.

1)	We started to create Estonian wordnet in 1997. The work was funded partly by Estonian Science Foundation and partly in the frames of Estonian National Programme of Language Technology. Before co-operating with EWN-2 we reached to create about 900 synsets (mainly EWN-1 BCs translations into Estonian and about 150 synsets of 30 most frequent Estonian verb). The format of that former database was close to WordNet 1.5, but not a copy of that, so we could not use WN 1.5 interface to handle the Estonian wordnet.
For inserting lexical data to our former wordnet we used MS Word 7.0 macro (made by Filosoft). It offers windows with blank fields for filling them with lexical data, and it is able to check whether the inserted word does already exist in the database and in what synsets and contexts.
After our historical decision to use Polaris for developing Estonian wordnet we only change totally our former database format (with help some little UNIX scripts) to make it understandable for Polaris.
Today the Estonian wordnet contains about 1.600 synsets with 3.300 variants (literals) connected with each other mostly by hyperonymy/hyponymy relations.

2)	We have programs for morphological analysis, morphological disambiguation and morphological generation of Estonian.
The first two programs were used, for instance, to analyse and disambiguate the texts of sense descriptions (glosses) of Estonian Explanatory Dictionary (see 1.1.1) in the process of creating the first version of Estonian base concepts.

1.2. Procedure of the selection of BCs for Estonian

Here we will give a short description of the selection of BCs for Estonian. Depending from the resources which we had at our disposal we chose the following procedure.

1.	We made a frequency list of the words (lemmas) from the meaning descriptions (glosses) in the “Explanatory dictionary of Estonian” (see also 1.1.1). These list contained 488.739 word forms, 62.828 lemmas.
Word forms were disambiguated morphologically, but not semantically. The latter work had to be done manually afterwards. We chose 1649 most frequent words (including 1133 nouns (F>46) and 516 verbs (F>40)) for further work.

2. 	We had before translated the EWN-1 BC synsets into Estonian. Now we compared the words from these Estonian translations with the frequency list described above and selected the overlapping lemmas. These were included in the prospective list of BCs. The list contained 476 words of Estonian (358 nouns and 118 verbs).

3. 	Because we did not have any reliable objective information about the possible position of the chosen words in a semantic hierarchy we fixed a conventional limit of words (concepts) for the candidates of BCs: about 1000 concepts, of these about 700 nouns and about 300 verbs. Thus we had to translate additionally about 350 noun and 180 verb meanings. Since many words were polysemous, we had to disambiguate them and to decide which meanings should be included to the set of BCs. In the course of this work also a number of words present in the frequency list had to be excluded as they quite apparently were too specific (e.g. such linguistic terms as adjektiiv ‘adjective’  or the names of concrete animals) or, in case of some verbs, appeared frequently only in different expressions (it means, their meaning(s) as single word is rare).
As a result, we have come to the present list:
698 noun BCs with 723 relations to ILI
366 verb BCs with 423 relations to ILI

1.3. Some experiences and problems in working with test samples and Base Concepts.

Below we list some (most typical) problems in determining correspondences between Estonian and English (ILI) concepts:

1)	In the case of verbs there is a quite regular discrepany between English and Estonian in the expression of causativity. In Estonian causative counterparts of noncausative verbs  are regularly lexicalized, also different lexical entries, and the opposition is productive. For instance, to move(by itself) is liikuma, to move (something) is liigutama. As a result, there exist cases where in English there are verbs which have only causative or only noncausative meaning, but in Estonian both meanings are lexicalised and used productively. For instance, the English verb to spend (money) is translated as kulutama, but there is also noncausative kuluma (also about money) for which no exact English lexicalised counterpart exists (the dictionary translation is be spent but the Estonian kuluma has no passive meaning). The same helds e.g. about levitama (to disseminate, distribute) and noncausative levima.

2)	The cases where the meanings of Estonian and English (EWN) words do not match exactly are quite numerous. In these cases mostly the relation eq_near_synonym has been used.

For instance, it is difficult to find exact match in English for the Estonian verbal synset vältama, kestma “to go on for a certain period of time”. No meanings of English last or endure do correspond to this meaning exactly. In the same way, in Estonian the verb harrastama is more or less monosemic, but in Estonian-English dictionaries there can be found translations as  to go in for, to take an interest in, to fancy, to indulge (in) etc.

3)	Lexical gaps were found in Estonian as compared to English as well as vice versa.

For instance, in the field of motion no exact lexical counterparts can be found for English to impel/ move fordward/ propel, or for to travel (in the sense “undergo transportation”). In the field of food there is no Estonian counterpart of the noun synset edible, comestible (the Estonian translation söödav is an adjective or participle, not a noun).
In such cases the links to ILI concepts can be established, as a rule, via has_eq_hyperonym relation. 

When looked at from the point of view of Estonian, the cases of causative or noncausative verbs as described above is one systematic example.

4)	In some cases there were problems with applying directly the (hierarchical) relations provided by ILI. Some examples from the field of food.

-	Some Estonian synsets did not fit in any normal way to the hyperonymy/hyponymy hierarchy directly under toit, toitaine (food): käik (course), lisand (condiment), portsjon (helping, portion). In these cases some indirect relations were established.

-	In some cases more than one hyperonyms were fixed for one concept. For instance: magustoit, järelroog (dessert, sweet) has hyperonym käik (course) as well as toit, roog (dish).

-	In some cases an intermediate level was added as compared to the ILI hierarchy. Consequently some synsets were grouped under this new concept one level lower than in ILI. For example loomasaadus (ILI near synonym animal product) became the hyperonym to liha (meat). Thus concepts of the same level (sweetmeat and animal product) became of a similar degree of generality.

-	After translating the provided words into Estonian and fixing their relationships it seemed reasonable, from the point of view of Estonian, to add a number (in the case of the field of food about 20) of synsets which have the same semantic status as representatives (hyponyms) of some higher level concept as compared to those provided in the list. For instance: since in the list there exist alkohol (alcoholic beverage) and piim (milk), also concepts for karastusjook (refresher), mahl (juice), kohv (coffee), tee (tea) were created.

In sum, however, as our experience shows, the difficulties are not insurmountable and it is fully possible , using the EWN methodology, to find correspondences between Estonian and other languages (in the given case, English) via ILI.

2.	CZECH WORDNET

2.1 Tools and Resources

2.1.1  The following tools are being used in the continuing work on Czech Wordnet:
i) Specialized sorting program developed by P.Sevecek for various types of dictionary processing,
ii) 	A simple parsing program able to analyze dictionary entries in Explanatory Dictionary of Czech (EDC) and select genus proximum definitions,
iii) 	A simple translating program able to process a bilingual dictionary (Czech-English-Czech): it uses a simple pattern matching and associates Czech entries with their English equivalents and then tries to link them with the WordNet 1.5 synsets,
iv) 	A program able to compute MI (mutual information) score from Czech text corpus ESO has been developed by P.Rychly and used to obtain the list of present-day Czech collocations,
v) 	Czech lemmatizer by P.Sevecek and K.Osolsobe, containing 165 000 Czech stems and able to perform full morphological analysis of an arbitrary Czech text (also used for tagging corpus texts in corpus ESO).
vi) 	Polaris 1.3.6 tool obtained from P.Vossen of Amsterdam has been explored and acquired for the further work, particularly for the processing of the sense links.

2.1.2 The following resources have been further used in building Czech WordNet: 
i) Extended Explanatory Dictionary of Czech (EDC, by P.Sevecek and K.Pala, Brno 1997,
	present size: approx. 45 000 entries, in electronic form, with automatic lemmatization, word form recognition and basic word derivation,
ii) 	New extended version (v.2.0) of bilingual Lingea Lexicon: Czech-English-Czech, by Lingea Ltd., Brno 1997-98,
	present size: approx. 75 000 entries, in electronic form (on CD ROM) with automatic lemmatization, word form recognition and basic word derivation,
iii) 	Dictionary of Czech Synonyms, by K.Pala and J.Vsiansky, NLN, Prague, 1994-1995,
	size: approx. 20000 synsets (entries), its electronic version with automatic lemmatization, word form recognition and basic word derivation was linked to the Lingea C-E-C Lexicon,
iv) 	A list of Czech collocations containing approx. 100 000 lines has been obtained from the text corpus ESO (approx. 61 mil. word forms, built and mantained at the Faculty of Informatics), sorted according several criteria (MI score, frequencies, syntactic criteria) and prepared for the processing of the present-day Czech collocations,
v) 	Fully tagged corpus DESAM (both structurally and grammaticaly) that has been compiled at the Faculty of Informatics. It contains mostly newspaper and magazine texts from 1992-96,
	size is 1 mil. Czech word forms and has been used for finding collocations,
vi) 	Corpus ESO built at the Faculty of Informatics in the course 1998 from newspaper and magazine texts (1996-98),
	size 61 mil. Czech word forms, partially tagged (lemmatized), has been used as a source of collocations..

2.2 Selecting Czech Base Concepts

2.2.1. We  prepared a tentative list of Czech Base Concepts candidates containing 1888 items -- we have obtained it from the following resources:
1)	Explanatory Dictionary of Czech (EDC), the author is P.Sevecek, Brno 1997, size: approx. 37 000 entries, in electronic form,
2)	Dictionary of Literary Czech, authors: J.Filipec et al, Academia, Prague, second edition 1994, printed version, size: about 50 000 entries,
3)	Bilingual Lingea Lexicon: English-Czech-English, by P.Sevecek, Brno 1997, present size: approx. 40 000 entries, in electronic form with automatic lemmatization,
4)	Dictionary of Czech Synonyms, by K.Pala and J.Vsiansky, NLN Prague, 1994-1995, size: approx. 20 000 entries, in electronic form with automatic lemmatization -- it will be used a bit later when synsets will be introduced into Czech WN.

The list mentioned above has been obtained by sorting out the entries in 1) and 3) containing genus proximum (hyperonym) definitions. This was done with simple converting program written by P.Sevecek. Then the frequency criteria were applied which gave us a smaller list containing 527 items (the lowest frequency was 5) and this list is our first version of BC's. It contains links to WN 1.5 meanings and exists both in text form (in our format) and also in LWN Import-Export File Format.

2.2.2. In the second step we associated the tentative list with English equivalents - those were obtained from the Czech-English and English-Czech electronic dictionary (Lingea E-C-E electronic Lexicon).

2.2.3. Then, having the list with Czech senses obtained from EDC and English equivalents from Lingea Lexicon it was possible to use WN 1.5 resource and to associate Czech senses with the WN 1.5 ones. This resulted in the first version of the list of BC's.

2.2.4. The last step consisted in converting the above list into LWN format.

2.2.5. After checking the list of Czech Base Concepts we will try to add the synsets to these items - for this we will use as a resource Dictionary of Czech Synonyms (by K.Pala and J.Vsiansky) which also exists in electronic form. However, this will take some time because we have to differentiate better the possible meanings and that should be, I am afraid, done manually.

2.3 Further work and problems
Earlier prepared tentative list of Czech Base Concepts candidates containing 1888 items – both nouns and verbs has been further processed, refined and enlarged.

2.3.1. Further work

First some quantitative data about the present state of the Czech wordnet:

Synsets:		6377
Nouns			4227
Verbs			350
noun collocations	1800
senses			7876
senses per synset	1,23

The work has proceeded in the following way.

i) 	The list of synsets has been further checked and a special attention has been paid to the more subtle differentiation of the senses within Czech synsets. Also their links to WN 1.5 senses have been examined in our working format and then imported to LWN Import-Export File Format and checked using Polaris tool. This work is still going on.
ii) 	In the next step the above mentioned pattern matching program has been used that associated Czech and English equivalents (via Lingea C-E-C Lexicon) with the corresponding WordNet 1.5 synsets – in this way a larger list of Czech synsets has been produced containing now approx.6000 Czech noun synsets.
iii) 	The list of Czech verb synsets (300 verbs) has been checked with regard to the senses (this represents a sort of problem since the existing resources are not always reliable enough in this respect) and their links to WordNet 1.5 synsets.This resulted in the second version of the list of Czech BC's containing now approx. 350 verbs. More attention will be paid to the verbs in the next stage.
iv) 	The list of present-day Czech collocations that can be used as synsets or form elements of some synsets has been compiled (approx. 1800 items) and integrated into the present Czech WordNet.
v) 	The last step consisted in putting the mentioned lists (without verbs) together and converting the resulting list into LWN Import-Export File format using Polaris tool. This list is a part of this Deliverable as a separate Appendix.
vi) 	When working both on the noun and verb synsets we paid attention to the problem of the translation equivalents. The experience with them can be generalized in the following way: the highly inflectional nature of Czech with its rich formal and derivational morphology causes that in some standard cases the straightforward English translation equivalents either cannot be easily found or have to be substituted by the various syntactic constructions. We will give an overview of these problems in the next section.

2.3.2 Problems with Translation Equivalents and Gaps
When working both with the noun and verb synsets in Czechwe have faced the problem of the translation equivalents and corresponding gaps with regard to English. Our experience with them can be put in the following way: the highly inflectional nature of Czech with its rich formal and derivational morphology causes that in some typical cases the straightforward English translation equivalents either cannot be easily found or have to be substituted by the various syntactic constructions or context dependent equivalents have to be searched for. At the present moment at least four types of basically morphological phenomena causing the gaps should be mentioned: 
1) 	verb aspect 
2) 	reflexive verbs 
3) 	verb prefixation (single, double) 
4) 	deminutives (noun derivation by suffixation),
5) 	move in gender (noun derivation by suffixation).

1. 	Verb Aspect: Imperfectives, Perfectives and Iteratives:
There are two aspects in Czech: imperfective – perfective, iterative is sometimes classified as a third aspect but formally it belongs under the imperfective. Thus Czech verbs typically occur in pairs and the aspect distinctions have to be captured systematically in the whole lexicon (according to our estimation there are at least 30 000 verbs in Czech and for each verb an information about its aspect must be present in a dictionary entry). The iteratives are formed separately (mostly by alternations in stem). There is only a small number of basic verbs that do not enter into the aspect pairs, eg. být, mít, moci, muset, chtít, myslet, vědět... (to be, to have, must, want, think, know...), there are about 50 of them. As an example of typical pairs where the first verb in the pair is imperfective and the second one perfective we can give:
brát : vzít (with only one English equivalent – take) or 
brát si, brát se : vzít si, vzít se (refl., take for one’s benefit : take and have it, marry : get mar.
dělat : udělat (do, finish doing)
dávat : dát (keep giving: give and finish giving).

In our opinion, the fact that aspect is a grammatical category in Czech is the reason why the appropriate lexical equivalents in other languages are not always easy to find and syntactic constructions of various types have to be looked for and used instead. The aspect distinction in English can be expressed lexically (think : break or know : hit), or in a different way by various tense constructions as e.g. tense forms (have been done, had done, am doing).

The existence of the aspect in Czech explains why we have quite simple tense system: present, past (preterite) and future, in comparison with more complicated tense system in English. The tenses are intertwined with the aspect quite closely, e.g.:

present tense: beru (I take, I am taking) : vezmu (I will take, I will be taking an finish it)
past tense: bral jsem (I were taking) : vzal jsem (I took sth and finished taking )
future tense: budu brát (I will take, I will be taking) : vezmu (I will take and finish it )

a) 	imperfective verbs are used when the action denoted by a verb is understood as not limited 
in time, as going on, lasting, not finished (within no limited time interval). Thus brát basically 
means to take but taking is understood as not finished and still going on. Then 
(1i) Pavel bere do ruky tu disketu.
 can reasonably be translated as 
(1i-a) Pavel is taking the diskette into his hand.
and we do not know whether taking was finished or is still going on. The imperfectives are understood as unmarked and that is why they typically have the straigthforward equivalents in bilingual dictionaries. However, the perfective counterpart of brát is vzít, so the sentence 
(1p) Pavel vezme do ruky tu disketu.
 has to be translated as 
(1p-b) Paul will take the diskette into his hand and will finish taking it.
and not as
(1c) Paul takes the diskette into his hand.,
since the perfective verb refers to the action completed in time, therefore its present tense form expresses future – the action starting now can only be finished in future. Note that instead of the lexical equivalent we have to use a syntactic construction in English to obtain an equivalent sense and that can be done only on the sentence level.
However, the situation can be even more complicated: some Czech verbs can be at the same time marked as reflexives occurring with the reflective pronoun (particle) se, si (self) which means that we have the following variants for the mentioned pair:
brát: vzít  take : 0 (not reflexive)
brát se : vzít se  marry : to get married (each other)
brát si koho : vzít si koho  be marrying sb – to get married with sb (complete it) 
brát si co : vzít si co  be taking sth for oneself (for one’s personal benefit) : complete taking 

b) 	perfective verbs are used when we want to refer to the verb action as limited in time, as
finished in some time point, as going within a certain interval. Then Czech sentence 
(2p) Pavel vzal tu disketu do ruky.
 with perfective vzít in the (simple) past can be best translated into English as 
(2p-a) Paul has taken the diskette into his hand. (and is still holding it),
because Czech vzít means to take sth but at the same time also to finish the process of taking completely. Generally speaking, what we have here is 2:1 mapping, thus it is obvious that some of the Czech senses of brát and vzít will not have their direct equivalents in English and also in other languages which do not have aspect as a grammatical category. 
c) 	iterative verbs are used when we need to refer to a verb action as taking place regularly,
repeatedly. Thus hrávat  means use to play, to play regularly as in the sentence 
(3it) Hrávali tenis každou sobotu.
that can be appropriately translated into English as a whole sentence:
(3it-a) They used to play tennis each Saturday.
It can be seen that in Czech hrávat is a good candidate of an independent synset which will include other respective iteratives (as members of the synset).

2. Reflexive verbs
The reflexives should be mentioned separately: there are 5 types of reflexives in Czech, we will characterize them briefly:
i) 	genuine reflexives (reflexiva tantum) – smát se, zasmát se  (*smát, *za-smát) : laugh, they occur in Czech dictionaries as independent entries (synsets), there are about 3000 items of this sort,
ii) 	verbs having reflexive meaning and expressing that an action is performed on the subject itself – holím se : holím koho – I shave myself : I shave sb
iii) 	verbs expressing reciprocity – milují se : milují – they love each other : they love sb 
iv) 	verbs with reflexive beneficiary dative – dát si pivo : to have a beer for himself (and enjoy it)
v) 	reflexive passive – dům se staví – the house is being built
vi) 	impersonal reflexives occuring only in 3rd person sg – pracuje se na tom : they work on it, it is being worked on it

3. Prefixed verbs 
Prefixation is a morphological means that is standardly used:
1) 	for expressing the aspect distinctions as in číst : pře+číst (read : read through)
and also 
2) 	for word derivation (new verbs) as in myslet : roz+myslet (think : think over).
Typically almost any Czech verb can be prefixed, sometimes with double prefixes. The number of prefixes is about 20 simple prefixes+ 15 complex ones often coming from other languages (mostly from Latin or Greek). The prefixed verbs can be in a way compared with phrasal verbs in English, however, the correspondencies are not very regular.
Thanks to the possibility to derive new verbs by means of prefixation in Czech one can derive verbs that do not have straightforward equivalents in English and probably in other languages as well. To give an example: from Czech verb myslet (to think) a number of verbs can be derived not having the appropriate equivalents and have to be translated ad hoc using various syntactic constructions:
myslet  do + myslet => E_eq: think through (all consequences), no eq. in WN 1.5
               od + myslet (si co) => E_eq: think apart, no WN 1.5 equivalent
              pro + myslet (co, si co) => E_eq: think through, think out
              při + myslet => E_eq: add a thing to ones mind, fill in the details, no eq in WN
              roz + myslet (co, si co) => E_eq: think over, reflect upon
              vy + myslet (co, si co) => E_eq: devise, invent, think up
           za+myslet se = > E_eq: do a bit of hard thinking, be absorbed in thought, noWN eq
             (zahloubat se);
The following examples have been found in Czech computer manuals:
sense 1......pře + skočit => E_eq: skip: skip all, skip over, omit, no WN 1.5 eq for přeskočit 
sense 2 .............................E_eq: jump over (hypern.relation motion)
iterative... přeskočit => přeskakovat: E_eq: use to jump over (repeatedly), no WN 1.5 eq
dělat => udělat => dělávat: E_eq: do, have done or complete doing, use to do, no WN 1.5 eq
programovat => naprogramovat: E_eq: programme, complete programming, no WN 1.5 eq.
.................... => přeprogramovat: E_eq: re-programme, programme again
hodnotit => z+hodnotit => zhodnocovat: E_eq: s1: evaluate,s2: valorize, no WN 1.5 eq
...................pře+hodnotit =>přehodnocovat: E_eq: re-evaluate, use to re-evaluate, no WN eq

Examples of the double prefixes:
vy-skočit: po-vy-skočit : jump up a litle, po-vy-skakovat : jump out of sth one after another
pře-psat : rewrite, pře-pisovat: keep rewriting, po-pře-pisovat : rewrite gradually
vytáhnout: pull out, vytahovat : keep pulling out, na-vy-tahovat : pull out in a distributed way
roz-dat: distribute, roz-dávat : keep distributing, po-roz-dávat : distribute one after another
transformovat : keep transforming, pře-trans-formovat: complete, finish transforming,
učit: keep teaching, na-učit : complete teaching, od-na-učit : complete weaning (lose knowledge), od-na-učovat : keep weaning

4. Nouns – Deminutives
They are formed by the respective derivational suffixes in a standard way and can be derived from the majority of Czech nouns. The deminutives can be used to refer either to small things (objects, in most cases) or to any object to which one can have an emotional relation. This double nature of the deminutives is obviously the main cause of the problems with the translation equivalents. 
   However, some of the deminutives are now lexicalized and though they display deminutive form, in fact some of their senses are not deminutive and they can refer to the normal objects or things as well: obrázek, ručka, domek,...(picture, hand, house or cottage) One can speak about 2 or even 3 levels of the deminutive derivation as in:
sense 1...obraz, obrázek : picture
         2......................: small picture
         3......................: emotional relation (has no lexical one-word equivalent in WN 1.5)
sense 1............voda : (vodka) vodička : medicine
         2.....................: small water
         3.....................: emotional relation
sense 1 dům : domek : house, cottage
         2..................... : small house
         3......................: emotional relation 1
sense 1 domeček: wendy house (plaything),
         2......................: small house
         3.....................: emotional relation 2 
sense 1........ kočička : kitten, pussy, (kotě, koťátko – emotional relation 2) 
         2...................... : catkins
         3...................... : small cat (not necessarily kitten)
         4...................... : emotional relation 1
         5...................... : nice (young) girl (woman)
sense 1............(ruka) ručka : hand
         2.....................: small hand
         3.....................: emotional relation 1 
sense 1..........ručička : hour hand
         2.......................: small hand
         3......................: pointer, needle
         4.....................: emotional relation 2
sense 1..............lvíče : cub, more exactly lion’s cub (has eq hyperonym). 

5. Move in Gender: Masculine Nouns and their Feminine Equivalents 
For each masculine noun denoting a male entity a corresponding noun having the same sense and denoting a female entity can be regularly derived in Czech. Thanks to this regularity it is not always easy to find their appropriate translation equivalents in English. In our view, the main problem here is whether to keep these cases within one synset (as in WordNet 1.5) or to have two synsets related to each other by the gender-move relation (as in Czech dictionaries). As far as I know there is a similar derivational pattern in German which is probably used as frequently as in Czech. The comparison via ILI can give very interesting results: they will show the degree of similarity in gender-move with regard to both languages. We think that the problem is general enough and it may be interesting to see how it manifests itself and in what degree it appears in other languages as well and thus calls for a more specific solution. 

 Regular derivation of the nouns denoting female partners:
absolvent – absolventka : graduate – she graduate,
anesteziolog – anestezioložka : anaesthetist, anesthesiologist – she
pronásledovatel – pronásledovatelka :  pursuer – female pursuer
travič – travička....... sense1: poisoner,
                                  sense2: grass, 
                                  sense3: small grass
                                  sense 4 emotional relation
trapič – trapička : tormentor – female tormentor
sexuolog – sexuoložka : sexuologist – female sexuologist
sybarit, požitkář – sybaritka, požitkářka : sybarite – she sybarite
skokan........sense1... frog, no female eq in Czech
                   sense2...jumper, (hyperonym relation – athlete),  skokanka : she jumper
                   sense3...pole-vaulter, (hyperonym – athlete), skokanka (o tyči) : she pole-vaulter 

6. Conclusions
The described phenomena, in our view, are relevant in the WordNet context and they can be generalized in the following way:
a) aspect opposition is a ternary relation – imperfectives – unbounded in time
 - perfectives – bounded in time
 - iteratives – iterative, bounded in time
Now the question is: shall we have one synset for each of the mentioned verb type or should we have one synset for all? In our opinion, the appropriate solution, at least within the Czech wordnet, would be to introduce appropriate internal language relation(s) that could link together the respective synsets. In the case of aspect we would suggest to introduce internally in Czech WordNet as a new kind of ILR something like X_HAS_IMPF, X_HAS_PERF, X_HAS_ITER attributes. With regard to ILI, however, it seems to be reasonable not to project these differences further (since it would call for a verb subclassification).

b) reflexives
At least three possibilities have to be taken into consideration:
- reflexiva tantum 
- reflexivity
- reciprocity
The suggestion is to have them systematically as separate synsets as it is standard in Czech dictionaries but again – we would not project them into ILI but we will have appropriate attributes in Czech WordNet. Other cases of reflexive verbs belong to the syntactic level.
c) prefixed verbs
They combine the aspect distinctions with iterativity and various types of the distributed actions, thus they are sources of many gaps. Some of them can be translated by phrasal verbs but there is not very much regularity in this respect. The use of the relation HAS_NEAR_SYNONYM is a possible solution, though within Czech WordNet we have to mark them.
d) 	gender pairs
They display binary semantic opposition – male : female, and the question is again the same as above: shall we have this distinction in one synset as it is in English WordNet or it is reasonable to keep them apart as a separate synsets and have a special attribute with two values for them, say: X_HAS_MALE – X_HAS_FEMALE?
e) deminutives
They display a sort of ternary semantic opposition as in the case of aspect, however, there is, a relevant difference: one of the attributes expresses an emotional attitude of the speaker in an lexicalized way. Thus, as we have indicated above, the following cases can be found in Czech deminutives:
- standard, as in dům, domek  (in English house, cottage)
- small thing as in domek, domeček (small house, Wendy house)
- emotional attitude as in domek, domeček (something like my dear little house).
To preserve this information inCzech WordNet we suggest to introduce (temptatively) the following attributes: X_IS_SMALL and X_EXPRESSES_POSITIVE_EMOTION.

Generally, however, we are prone to the opinion that it would be reasonable to re-evaluate the ILR table and to consider the possibility of adding the new attributes to the ILR with consequences for ILI as well: when other typologically differen languages will be in future attracted to WordNet approach (such as Greek, Finnish or Hungarian) it will be necessary to look for a more consequent solution anyway. Our suggestion (based on the experience with GENELEX which comprised French, Czech, Polish and Hungarian) would be to have the optional attributes in the ILR table (or slots specific to the particular languages). What remains to be solved is the question how to build these language specific attributes into ILI and how to relate them reasonably but the idea of optional slots should certainly be considered.