Download Lecture slides - CSE, IIT Bombay

Linguistics Lecture-2:
Morphological Processes
Pushpak Bhattacharyya,
CSE Department,
IIT Bombay
21 June, 2008
Base form and Morphed form
POS
Base form
Morphed form
Noun
boy
boys
Verb
buy
buys
Adjective
acchha (good)
achhii (good)
Adverb
quickly
quickly
(normally do not
change)
Morphing and Agreement
• Key notion
• English: verb agrees with the subject
– Ram laughs; Children laugh
• Hindi: adjective (often) agrees with the
noun it modifies
– achchha ladkaa; achchhii ladkii
Key concepts: Inflection and
Derivation
• Inflection
– Does not change POS:
• transport (V) transporting (V, present progressive)
• boy (n)  boys (n, pl)
– Closes the morpheme- cannot transform any more
• Derivation
– Changes the POS
• transport (V) transportation (n) transportations (n, pl)
• delight (n) delightful (adj)
Key concepts: factors affecting
noun morphology
• Number
– Singular, plural, dual (sanskrit)
• boy, boys, baalakou
• Direct/oblique case
– ladkaa (boy), ladke (boy) ko (to, accusative)
6 base cases
Case
Base
Morphed form
Normal semantic
role (relationship
with the
governing verb)
Nominative
ladkaa (boy)
Ladkaa*
agent
Accusative
ladkaa
Ladke ko (to the
boy)
object/patient
Instrumental
ladkaa
Ladke se (by the
boy)
instrument
Dative
ladkaa
ladke ko (to the
boy)
indirect
object/beneficiary
Ablative
ladkaa
Ladke se (from the
boy)
Source
Locative
ladkaa
Ladke me (in the
boy)
site/time of action
*- takes ergative marker ne for transitive verb past tense
Syncretism
•
•
•
•
Same suffix playing multiple roles
se is syncretic: instrumetal, ablative
to is syncretic: accusative, dative
Challenge for morph analyser
Key concept: derterminants of verb
forms
• GNPTAM: gender, number, person, tense,
aspect, modality
• Gender: masculine (m), feminine (f), neuter (n):
only first two in Hindi
• Number: singular (s), plural (p)
• Person: 1st, 2nd, 3rd: I, you, he/she
• Tense: present, past, future (past and non-past)
• Aspect: progressive, perfect
• Modality: Indicative, durative, ability, possibility,
subjunctive etc.
Large number of possibilities
•
•
•
•
•
•
•
Gender: 3
Number: 2 (3 for some languages)
Person: 3
Tense: 3 (2 for some languages)
Aspect: 2
Modaliity: 7-8
Total possibilities:
– 3 X 2 X 3 X 3 X 2 X 8=864
• Much larger for many languages: Arabic,
Turkish, Hebrew (Semitic languages),
Hungarian, Finnish
Example: verb forms (few cases)
Factor
Form
Gender
raam jaataa haai; sitaa jaatii haai
Number
ladkaa jaataa haai, ladke jaate haiM
Person
meiM jaataa huM; tum jaate ho; vaha
jaataa hai
raam jaataa haai; raam gayaa; raam
jayegaa
raam jaa rahaa haai; raam jaa chukaa
Tense
Aspect
Modality raam jaa sakegaa; raam jaa paayegaa
S-form, Ing form, D-form, N-form, Irregular
forms: corresponding PENN POS tags
• 3rd person, singular number, present
tense: laugh laughs (VBZ)
• Present participle: laughing (VBG)
• Simple past: Transport Transported
(VBD)
• Past participle: had transported (VBN)
• Take Took (VBD); Take-> Taken (VBN)
Verb types (syntactic Classification:
traditional linguistics)
Verb
Intransitive (no direct object)
Transitive
(has direct object)
Unergative
Unaccusative
Verb types (semantic classification:
Universal Networking Language (UNL))
Verb
Do
(Action)
Be
(Stative)
Occur
(happen)
Verb categorization in UNL and its relationship to
traditional verb categorization
Traditional
Intransitive
(sytactic)
Transitive
UNL
(has direct
object)
Unergative
(syntactic subject
=semantic agent)
Unaccusative
(syntactic subject
≠ semantic agent)
(semantic)
Do
(action)
Be
(state)
Occur
(event)
Ram pulls the Ram goes home
rope
Ram knows
mathematics
Ram forgot
mathematics
(ergative
languages)
Ram sleeps
Earth cracks
Ergative Verbs in English
•
•
•
•
Break
Ram breaks the window
The window breaks
The object can take the subject position
without changing the verb form
• However dooccur
Unergative construction in Hindi
• raam ne khaanaa khaayaa
• For transitive verbs in past tense
• Syntactic subject not in nominative form