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About WordNet

 

The WordNet is an online lexical resource. It is a lexicon based on psycholinguistic principles. It organizes the lexical information in terms of word meanings. It is a system for bringing together different lexical and semantic relations between words. The WordNet is being developed using the expansion approach with the help of tools provided by IIT Bombay.

 

In a language a word may appear in more than one grammatical category and in a grammatical category a word can have multiple senses. These categories and all senses are captured in the WordNet. WordNet supports the grammatical categories namely Nouns, Verbs, Adjectives and Adverbs. All words which depict the same sense (same meaning) are grouped together to form a single entry in the WordNet. This forms synonym set, or synset. Synsets are the basic building blocks of WordNet. For each word there is a synonym set, or synset in the WordNet representing one lexical concept. This is done to remove ambiguity in cases where a single word has multiple meanings.

Each entry in the WordNet consists of following elements:

 

  • Synset: It is a set of synonymous words. For example, “शाळा, विद्यालय, स्कूल” (SALA,viDyAlaya skUla) represents the concept of school as an educational institution. The words in the synset are arranged according to the frequency of usage.

 

  • Gloss: It describes the concept. It consists of two parts:

 

  1. Text definition: It explains the concept denoted by the synset. For example, “जंय मुळाव्या वा माध्यमीक पांवड्याचें शिक्षण दितात अशी सुवात” (jaMya muLAyA vA mAdhyamIka pAMvaDyAceM SixaNa ditAta aSI suvAta ) explains the concept of school as an educational institution.

 

  1. Example sentence: It gives the usage of the words in the sentence. Generally, the words in a synset are replaceable in the sentence. For example, “हे शाळेंत पयली ते पांचवी मेरेनचें शिक्षण दितात (he SAleMta payalIM te pAMvI merenaceM SixaNa ditAta) gives the usage for the words in the synset representing school as an educational institution.

 

  • Ontological Details (discussed below)
  • Semantic and Lexical relations (discussed below)

 

Each entry follows the principles of minimality, coverage and replaceability

  • Minimality: Only the minimal set that uniquely identifies the meaning is first used to create the sysnet, e.g., {ghar, kamaraa} (room) ghar - which is ambiguous - is not by itself sufficient to denote the concept of a room. The addition of kamaraa to the synset brings out this meaning uniquely.

 

  • Coverage: Next, the synset should contain all the words denoting a particular meaning. The words are listed in order of decreasing frequency of their occurrence in the corpus.  {ghar, kamaraa, kaksh} (room)

 

  • Replaceability: The words forming the synset should be mutually replaceable in a specific context.

 

  • Position in Ontology: An ontology is a hierarchical organization of concepts, more specifically, a categorization of entities and actions. For each syntactic category namely noun, verb, adjective and adverb, a separate ontological hierarchy is present.

 

Each synset is mapped into some place in the ontology. A synset may have multiple parents. The ontology for the synset representing the concept school is shown in figure 1.

 

Relations in WordNet

 

A WordNet is a word sense network. A word sense node in this network is a synset which is regarded as a basic object in the WordNet. Each synset in the WordNet is linked with other synsets through the well-known lexical and semantic relations of hypernymy, hyponymy, meronymy, troponymy, antonymy, entailment etc. Semantic relations are between synsets and lexical relations are between words. These relations serve to organize the lexical knowledge base. The Lexical and Semantic relations are described below.

 

 

LEXICAL RELATIONS

Antonymy: Antonymy is a relation that holds between two words that (in a given context) express opposite meanings. It is a lexical relation as it holds between two words and not the entire synset.

 

Example:

मोटो (moTo; fat) ==> किडकिडीत, बारीक, हाडकुळो, सुको (kiDakiDIta, bArIka, hADkuLo, suko; thin)
The words in bold face in the synset are in antonymy relation.

 

Gradation: Gradation is a lexical relation. It represents the intermediate concept between two opposite concepts. Figure 2 shows the gradation relation among three words.

 

Derived From: This relation specifies the root form from which a particular word is derived. This relation can go from noun to adjective or vice versa, noun to verb and adjective to verb and aims to handle derivational morphology. This is a lexical relation.

 

Example:

अनुक्रमान (anukramAna; step by step)
==> माळ (mAL; series)

 

SEMANTIC RELATIONS

 

Hyponymy and Hypernymy (is a kind of): Hypernymy is a semantic relation between two synsets to capture super-set hood. Similarly, hyponymy is a semantic relation between two synsets to capture sub-set hood. The hyponymy relation is transitive and asymmetrical. Hypernymy is the reverse of hyponymy.

 

Example:

बेलापान, बेलाचें पान, बेलपत्री (belApAna, belAceM pAna, belpatrI; a leaf of a tree named bela)
==>पान,पत्री (pAna, patrI; leaf) 
Here, बेलापान(belApAna; a leaf of a tree named bela) is a kind of पान(pAna; leaf) means पान (pAna; leaf) is a hypernym and (bel patrI; a leaf of a tree named bela) is the hyponym.

 

Meronymy and Holonymy (Part-whole relation): It is a semantic relation between two synsets. If the concepts A and B are related in such a manner that A is one of the constituent of B, then A is the meronym of B and B is the holonym of A. The meronymy relation is transitive and asymmetrical. Holonymy is the reverse of meronymy. It is used to construct a part-of hierarchy.

 

Example:

मूळ ( mULa, ; root)==> झाड, रूख (JADa, rUKa; tree)
Here, मूळ (mULa; root) is the part of झाड(JADa ; tree), meaning that मूळ (mULa; root) is the meronym of झाड (JADa ; tree) and झाड(JADa ; tree) is the holonym of मूळ (mULa; root).

 

Entailment: Entailment refers to a relationship between two verbs. Any verb A entails B, if the truth of B follows logically from the truth of A. The relation of entailment is unilateral, i.e., it is one way relation.

 

Example:

घोरेवप(Gorevapa; snore)
==> न्हिदप (Nidapa; sleep)

 

Troponymy: Troponym denotes a specific manner elaboration of another verb. It shows manner of an action, i.e., X is a troponym of Y if to X is to Y in some manner.

 

Example:

हांशें करप (hAMsheM; smile)
==> हांसप (hAMsapalaugh)

 

Causative: In there is a convention of forming causation by making morphological change in the base verb. The Causative relation links the causative verbs and the base verbs and show interdependency between them.

 

Example:

जेवण (jevaN; eat)==>लावप, भरोवप (lAvapa, Barovapa; to make someone eat)
लावप (to make someone eat) is a causative verb of जेवण(jevaN; eat).

 

Cross parts of speech linkage: Following relations are between the synsets of different parts of speech. Linkages between nominal and verbal concepts

 

Ability Link: This link specifies the inherited features of a nominal concept. This is a semantic relation.

 

Example:

नुस्तें (nusteM; fish) ==> पेंवता (peMvatA; swim)

 

Capability Link: This link specifies the acquired features of a nominal concept. This is a semantic relation.

 

Example:

व्यक्ती, मनीस, जन, लोक (vyaktI, manias, jana,loka; person)
==> पेंवता (peMvatA; swim)

 

Function Link: This link specifies the function of a nominal concept. This is a semantic relation.

 

Example:

शिक्षक, आचार्य, गुरु, मास्टर (Sixaka,AcArya, gurU, mAsTer; teacher)
==> शिकोवप, शिक्षण दिवप (shikovap; teach)

 

Linkage between nominal and adjectival concepts Attribute: This denotes the properties of noun. It is a linkage between noun and an adjective. This is a semantic relation.

 

Example:

सुकणें, शेंवणें (sukaNem, sheMvaNeM; bird) 
==> पांखां आशिल्लें (pAMKAM AshilleM; having wings)

 

Modified Noun: Certain adjectives can only modify certain nouns. Such adjectives and nouns are linked in the   WordNet by the relation Modifies Noun.

 

Example:

पात्र (pAtra, eligible)
==> व्यक्ती,मनीस (vyaktI, manIsa; person)

 

Linkage between adverbial and verbal concepts Modifies Verb: Certain adverbs can only go with certain verbs. Modifies Verb is a relation to show connection between such words.

 

Example:

केन्नाय (kennAya; sometimes) 
==> काम करप, कार्य करप (kAm karapa, kArya karapa; to work)