Concept (repetition)

• Abstract representation of the real world
• Mental representation of objects/actions/characteristics

Acquisition of meaning

• Acquiring in terms of already known concepts
• Concepts related to prototypes
• Prototypes are different
  • Individuals
  • Social groups
  • Cultures

Prototypes

• Knowledge of some objects
  • Represented mentally as prototypes
  • Rosch 1973.
• Example dog: medium-sized, hairy dog, not a chihuahua.
• Other members of class
  • Stored close or far away from the prototype
  • Called: graded membership

Relations between concepts

• IS_A relation:
  • A is a B
  • B is a C
  • Is A a C?
• PART_OF relation:
  • A is part of B
  • B is part of C
  • Is A part of C?
  A is part of B, B is a part of C
• HAS_PROP relation
  • A has property B

IS-A relation

• Superordinate: hypernym
• Subordinate: hyponym
• Relation: Hyponymy

PART-OF relation

• Also called meronymy or mereonymy
• Word is a part of something: meronym
• Large entity that has a part: holonym

What most lexicographers don't tell you....

• Analytical definitions used
• Analytical definitions work only for hyponymy relations
• Other relations are not necessarily transitive
• Natural concept systems do not rely on one type of semantic relation

Consequences of mixing semantic relations

• Knowledge network instead of knowledge tree
• Not all knowledge networks are identical
• Depends on individual background
• Lexical gaps
• Ambiguity

Ambiguity

• One word has two meanings: homonymy
• One word has two wordclasses: homonymy (can result in syntactic ambiguity
• One meaning has two words: synonyms
• One meaning has no word: lexical gap

Let's talk about truth: Propositions

• "What is expressed by a declarative sentence when the sentence is uttered to make a statement" (Lyons)
• Implies:
  • Different sentences can have the same proposition
  • One sentence can express more than one proposition
  • Not all declarative sentences express propositions
• Either true or false
  • Two valued system vs. many valued systems (modal logics)
  • Propositional variables: variables for facts, statements, propositions

Possible relations of propositions

• negation: p and -p: If p then not -p and if -p then not p
• conjunction: p ∧ q: if p is true and q is true then p ∧ q
• disjunction: p ∨ q: if p or q is true then p ∨ q (inclusive/exclusive)
• implication: if p then also q (symbol: p ⇒ q)
• equivalence: if p then q and if q then p (symbol: p⇔q or p≡q )

Ambiguity in terms of propositions

Two propositions are ambigue iff the relations between them are not unique.

Propositions and truth values

• Used for semantic analysis
• Describing the meaning of propositions in comparison to others

Semantic decomposition

	Bird	birds of prey	eagle
animate	+	+	+
bones	+	+	+
homoiotherm	+	+	+
feathers	+	+	+
meat eater		+	+
flying		+	+

Article from Oxford Advanced Learner's Dictionary of Current English

Abbreviation of the lexicon article

Decomposition of the lexicon article

Glossed lexicon article

List of parts of the lexical entry

Other representation format of the same thing

Orthography	Transcription	POS	Definition 1	Usage examples	...
unit	/juː nɪ t/	n	a single thing, person or group that is complete in itself, although it can be part of sth larger	a family unit

unit, /juː nɪ t/, n, a single thing, person or group that is complete in itself, although it can be part of sth larger, a family unit

The meanings of unit

• a single thing, person or group...
• a fixed amount or number... for measurement
• a group of people who perform a special function in a larger organization....
• a small machine that performs a special function....
• a piece of furniture or equipment....
• the smallest whole number....
• ....

Disambiguation strategies

• Extra information: POS, context, register, previous use, ...
• Statistical grounds: the one that is most frequently used, ...
• Convention: "that means..."
• "First come"

Word Sense Disambiguation

• Deep approach: using world knowledge
• Shallow approach: using a window of n-surrounding words for extra information
• Traditional problem of Natural Language Processing
• Problem for students translating with dictionaries...
• Why do students tend to go by the "first come" strategy?

Sorting lexicon articles

• Sort by lexical headword
• Alphabetically
• Other strategies possible?

Sorting strategies for lexicon articles

• Sorting by orthography of lexical headword: semasiological dictionary, example: bilingual dictionaries
• Sorting by meaning: onomasiological dictionary, example: thesaurus, terminology dictionary
• Others?

Other lexicon macrostructures

• Travel dictionaries: by thematic use
• Picture dictionaries: by thematic use
• Speech recognition: by pronunciation
• Part of speech: learner's grammar (!)

Apropos macrostructure

• Categorisation and search functions
• Semasiological macrostructure
  • form based
  • assigning meaning to a form.
  • Example:
    • word A: surface structure
    • assign definition and usage of the word
• Onomasiological macrostructure
  • concept/meaning oriented
  • assigns a form to a meaning
• Macrostructure possible based on each lexical data category in the microstructure

Why wait for morphology to finish with this?

• Headword selection in Latin dictionaries for verbs: 1st person singular
• German: infinitive
• English: morphological stem (!)
• How about languages with inflectional affixes?

Sorting strategies

• Alphabet: where do you include h@me; m@il; 4 u @ w@rk?
• Other alphabets: /sʌmθɪŋ/ Unicode value
• Syllaberies: し shi;ぎゃ gya Hiragana; Katakana/Kanji

Mesostructure

• Generalisations
  • inflectional patterns
  • derivational options
  • ...
• Metadata: information about the lexicon
  • lexicographer(s) names
  • applied theories
  • language
  • date
  • character set

Lexicon megastructure

• For print dictionaries
• Titlepage
• Front matter
• Back matter
• Lexicon body
• "Interjections" in the lexicon body

Homework for next week

1. Find examples for at least three different lexicon macrostructures. Copy (not photocopy) as much as necessary to show the differences. Describe the lexical keyword used and describe the lexicon macrostructure!
2. Take a look at the Oxford Advance learner's dictionary and describe the mesostructure. What are "study pages"?
3. Find homonyms in a lexicon and describe how you could disambiguate them!
4. Find pairs of propositions for each relation!

Class website

Return