Time, Tense and Aspect Rajat Kumar Mohanty rkm[at]cse[dot]iitb[dot]ac[dot]in...

Time, Tense and Time, Tense and AspectAspect

Rajat Kumar MohantyRajat Kumar Mohantyrrkm[at]cse[dot]iitb[dot]ac[dot]inkm[at]cse[dot]iitb[dot]ac[dot]in

Centre for Indian Language TechnologyCentre for Indian Language TechnologyDepartment of Computer Science and Department of Computer Science and

EngineeringEngineeringIndian Institute of Technology BombayIndian Institute of Technology Bombay

INDIAINDIA

Monday, April 25. 2005 Rajat NLP-AI Lecture Series, CFILT, IITB

OutlineOutline

• Time LineTime Line• Time and LanguageTime and Language• Grammaticalised Location in TimeGrammaticalised Location in Time• The Domain of Tense

– Tense in the Syntactic Domain– Tense in the Semantic Domain

• Aspect– Viewpoint type– Situation type


Time LineTime Line• Time can be represented as a straight line,

with the past represented conventionally to the left and the future to the right

• Whether the time line is bounded at either end : linguistically irrelevant, but philosophically important

past 0present

future

E SS P SP E P E

Representation of situations in the time line


Time and LanguageTime and Language

• All languages allow speakers and listeners to locate situations (i.e., event, process, state ) in time

• The idea of locating situations in time is purely a conceptual notion

• The ways of locating situation in time differ from one another on two parameters– the degree of accuracy of temporal location

that is achievable in different languages– the relative weight assigned to the lexicon and

to the grammar in establishing location in time


Grammaticalized Location in Grammaticalized Location in TimeTime

• Expressions for locating in time can be divided into three classes– Lexically composite expressions (e.g., five

minutes after John left, last year)– Lexical items (e.g., now, today, yesterday, last )– Grammatical categories (e.g., tense, aspect,

modals )

• Languages express location in Languages express location in time time by means by means of grammatical categories, of grammatical categories, e.g., e.g., (1) John sang (1) John sang (2) John sings(2) John sings(3) John sings(3) John sings (4) John is singing(4) John is singing

• The difference in (1) and (2) in English is The difference in (1) and (2) in English is tensetense

• The difference in (3) and (4) is The difference in (3) and (4) is aspectaspect


Tense in the Syntactic Domain

• The syntactic domain of tense is the clause• A tense morpheme is generated in each

clause• In Principles and Parameters Theory (now

The Minimalist Program) tense heads a functional category, i.e., TP

TP

T `NP

T

ti

VP

V `

NPNP

V

like

his teacher

Johni


Tense in the Semantic Domain• Semantic interpretation of tense requires

information from the contexts• Properties of Time in the semantic domainProperties of Time in the semantic domain

– There is the There is the timetime at which the act of speaking itself at which the act of speaking itself takes placetakes place

– There is a large set of There is a large set of timestimes at which various events take at which various events take placeplace

– There are all the There are all the timestimes other than the time of speaking, other than the time of speaking, which can serve as alternative points of reference for which can serve as alternative points of reference for the speakerthe speaker

• Each tense – involves three times: speech time, reference time and

event time – conveys information about two relations between them

• A relation between Speech Time and Reference Time • And, a relation between Reference Time and Event Time


Tense in the Semantic Domain

• Examples(1) Mary has arrived. (RT is the same as SpT)(2) Mary arrived. (RT is the same as ET)(3) On Sunday, Mary had already arrived.

• (3) is a past perfect that needs three different times for semantic interpretation: SpT, RT (the Sunday before), and ET

• The schematic meanings for the tenses of (1-3):– Present: RT = SpT, ET = RT– Past: RT < SpT, ET = RT– Past Perfect: RT < SpT, ET < RT



• Mary said last Tuesday that she was Mary said last Tuesday that she was leaving in 3 daysleaving in 3 days

• Temporal InterpretationTemporal Interpretation– Main clause: RTMain clause: RT11 < SpT; RT=last Tuesday; < SpT; RT=last Tuesday;

RT=ETRT=ET11

– Embedded Clause: RTEmbedded Clause: RT2 2 = RT= RT11; ET; ET22 > RT > RT22

Last TuesdayMary said

+3daysMary leave

Speech TimeET2

RT1=ETRT2



• Next Sunday John will have already Next Sunday John will have already arrivedarrived

• Temporal Interpretation:Temporal Interpretation:RT>SpT; RT=next Sunday; ET<RTRT>SpT; RT=next Sunday; ET<RT

John arrive

Next Sunday

Speech Time ET RT


• The function of tense is to locate the The function of tense is to locate the position of the speaker’s reference time, position of the speaker’s reference time, by relating it to a position of the time of by relating it to a position of the time of speakingspeaking

• Three primary possibilities for this Three primary possibilities for this relationshiprelationship– PastPast RT < SpTRT < SpT– PresentPresent RT = SpT RT = SpT – FutureFuture SpT < RTSpT < RT



AspectAspect• An event is said to evolve through a series An event is said to evolve through a series

of temporal of temporal phasesphases• One of these temporal phases is the actual One of these temporal phases is the actual

time of the event itself, inclusive of its end-time of the event itself, inclusive of its end-point point

• E.g., an event of building a houseE.g., an event of building a house• Verb aspectVerb aspect involves reference to one of involves reference to one of

the temporally distinct phases in the the temporally distinct phases in the evolution of evolution of building a housebuilding a house through time through time

Building a house

Result phaseDevelopmental phases

Starting point

End point(various processes associated with house-building)(the house exists)


Aspectual InformationAspectual Information• Tense interpretation interacts with aspectual

information• ExamplesExamples

(1)(1)Mary walked to school.Mary walked to school.(2)(2)Mary was walking to school.Mary was walking to school.(3)(3)Mary walked in the park.Mary walked in the park.

• (1) presents a complete event that has an (1) presents a complete event that has an endpoint, and the information that the goal endpoint, and the information that the goal was reached.was reached.

• (2) presents a part of the same type of event, (2) presents a part of the same type of event, but does not convey whether the goal was but does not convey whether the goal was reached.reached.

• (3) presents a complete event that does not (3) presents a complete event that does not involve a goal, and the information that the involve a goal, and the information that the event was terminated. event was terminated.


The Two Components in The Two Components in SentencesSentences

• The aspectual information is given by the The aspectual information is given by the linguistic forms that appear in a sentence. linguistic forms that appear in a sentence.

• Aspectual systems have two components: viewpoint and situation type

• Aspectual situation type indirectly classifies a sentence as expressing an eventuality, a state or an event. The information is conveyed by the verb constellation.

• Aspectual viewpoint, conveyed morphologically, focuses all or part of the eventuality.


Aspectual viewpoint types

• PerfectivePerfective– Perfective viewpoints focus a situation in Perfective viewpoints focus a situation in

its entirety, including both initial and final its entirety, including both initial and final endpoints.endpoints.

– e.g.,e.g., John has built a house. John has built a house.

• ImperfectiveImperfective– Imperfective viewpoints focus part of a Imperfective viewpoints focus part of a

situation, including neither initial nor final situation, including neither initial nor final endpoints.endpoints.

– E.g., Mary was walking in the parkE.g., Mary was walking in the park


The English Verb GroupThe English Verb Group

• On the original timetable for this project, by On the original timetable for this project, by this time the report this time the report would have been being would have been being printed.printed.

WOULD HAVE BEEN BEING PRINTED

Modal perfective progressive passive Main verb

Will +Past tense

have be + -en be + -ing print + -en(+ -en ) (+ -en )(+ -ing )

Modal aux Aspectual aux Copular auxAspectual aux


Temporal PropertiesTemporal Properties

• Dynamism: [static/dynamic]Dynamism: [static/dynamic]– StatesStates are static (undifferentiated period of states). are static (undifferentiated period of states).

EventsEvents are dynamic (successive stages of events). are dynamic (successive stages of events).

• Telicity: [telic/atelic]Telicity: [telic/atelic]– Events may be telic or atelic. A telic event has a Events may be telic or atelic. A telic event has a

natural final endpoint. It also includes events natural final endpoint. It also includes events without agents. An atelic event has no outcome. It without agents. An atelic event has no outcome. It has arbitrary final endpoint. (has arbitrary final endpoint. (e.g., walked to school, e.g., walked to school, walked in the park, etcwalked in the park, etc ) )

• Duration: [durative/instantaneous]Duration: [durative/instantaneous]– Situations are durative or instantaneous. (Situations are durative or instantaneous. (e.g.,e.g.,

strolled in the park, win the race, etcstrolled in the park, win the race, etc))


Telic EventsTelic Events

• Telic events may be classified by the Telic events may be classified by the type of result they bring about.type of result they bring about.

• Major type of resultsMajor type of results– Affected object: Affected object: bend an iron bar, break a bend an iron bar, break a

pot, wrinkle a dresspot, wrinkle a dress– Constructed object: Constructed object: build a house, write a build a house, write a

letterletter– Consumed object: Consumed object: drink a glass of wine, drink a glass of wine,

destroy a housedestroy a house– Affected experiencer: Affected experiencer: amuse Maryamuse Mary– Path-Goal: Path-Goal: walk to the lake, work from 2 to 3walk to the lake, work from 2 to 3


Temporal Features of the Temporal Features of the Situation TypesSituation Types

situations staticdurativetelic

stative

activity

accomplishment

semelfactive

achievement

[ + ]

[ + ]

[ + ]

[ - ]

[ - ]

[ - ]

[ + ]

[ - ]

[ - ]

[ - ]

[ - ]

[ - ]

[ + ]

[ - ]

[ + ]

examplesKnow the answer

Laugh, stroll in the park

Walked to school

Tap, knock

Reach the top, win the race


The Activity Situation typeThe Activity Situation type

• Temporal features: [dynamic], [atelic], Temporal features: [dynamic], [atelic], [durative][durative]

• Examples Examples – He is sleeping.He is sleeping.– They are widening the road. They are widening the road.

• Activities terminate or stop; the notion of Activities terminate or stop; the notion of completion is irrelevant to a process event.completion is irrelevant to a process event.

• Temporal schema of Activities: Temporal schema of Activities: I……FI……FArbArb


The Accomplishment Situation The Accomplishment Situation typetype

• Temporal features: [dynamic], [telic], Temporal features: [dynamic], [telic], [durative][durative]

• ExamplesExamples– Build a bridge, walk to school, drink a glass of Build a bridge, walk to school, drink a glass of

winewine

• Accomplishment s have successive stages in Accomplishment s have successive stages in which the process advances to its natural which the process advances to its natural final end point. They result in a new state.final end point. They result in a new state.

• The event is completed and cannot continue.The event is completed and cannot continue.

• Temporal schema of Activities: Temporal schema of Activities: I……FI……FNat RNat R


The Semelfactive Situation The Semelfactive Situation typetype

• Semelfactives are single-stage event with Semelfactives are single-stage event with no result or outcome.no result or outcome.

• They occur very quickly.They occur very quickly.• Temporal features: dynamic, atelic, Temporal features: dynamic, atelic,

instantaneousinstantaneous• ExamplesExamples

– Knock at the doorKnock at the door– The light flickerThe light flicker– Blink, coughBlink, cough

• Temporal schema of Activities: Temporal schema of Activities: EE


The Achievement Situation The Achievement Situation typetype

• Achievements are instantaneous Achievements are instantaneous events that result in a change of stateevents that result in a change of state

• Temporal features: dynamic, telic, Temporal features: dynamic, telic, instantaneousinstantaneous

• ExamplesExamples– Leave the house, recognize the person, Leave the house, recognize the person,

reach the top, break a glassreach the top, break a glass

• Temporal schema of Activities: Temporal schema of Activities: EE

RR


Major types of Results of Major types of Results of AchievementAchievement

• Affected object: Affected object: break a cup, tear a break a cup, tear a paperpaper

• Constructed object: Constructed object: imagine a city, imagine a city, define a parameterdefine a parameter

• Consumed object: Consumed object: explode a bombexplode a bomb• Affected experiencer: Affected experiencer: see a cometsee a comet• Path-Goal: Path-Goal: reach the top, arrive in reach the top, arrive in

MumbaiMumbai


Stative Situation typeStative Situation type

• States are stable situations which States are stable situations which hold for a moment or an interval. hold for a moment or an interval.

• Temporal features: static, durativeTemporal features: static, durative• ExamplesExamples

– Own the farm, be tall, believe in ghosts, Own the farm, be tall, believe in ghosts, hope that…, fears that…, know that…hope that…, fears that…, know that…

• Temporal schema of Activities: Temporal schema of Activities: (I)……(F)(I)……(F)


IllustrationsIllustrations

• John knew the truthJohn knew the truth (stative)(stative)• Suddenly Bill knew the truthSuddenly Bill knew the truth (achievement)(achievement)• Mary coughedMary coughed (semelfactive)(semelfactive)• Mary coughed for an hourMary coughed for an hour (activity)(activity)• John played cricket yesterday John played cricket yesterday

(accomplishment)(accomplishment)• Mary swam in the pond. Mary swam in the pond. (Activity)(Activity)• John wrote a letter.John wrote a letter. (Accomplishment)(Accomplishment)• Mary knocked at the doorMary knocked at the door (Semelfactive)(Semelfactive)• Mary reached the guest house (acheivement)Mary reached the guest house (acheivement)


Sources and Suggested Sources and Suggested ReadingsReadings

• Comrie, Bernard. 1995. Aspects. CUP.Comrie, Bernard. 1995. Aspects. CUP.• Comrie, Bernard. 1987. Tense. CUP.Comrie, Bernard. 1987. Tense. CUP.• Kearns, Kate. 2000. Semantics. Macmillan.Kearns, Kate. 2000. Semantics. Macmillan.• Smith, Carlota S. 1997. Smith, Carlota S. 1997. The Parameter of The Parameter of

AspectAspect. Kluwer Academic Publishers, . Kluwer Academic Publishers, Dordrecht.Dordrecht.

• Tedeschi, P. J. and Zaenen, A. 1981. Tense Tedeschi, P. J. and Zaenen, A. 1981. Tense and Aspects. and Aspects. Syntax and Semantics, Vol-Syntax and Semantics, Vol-14. 14. Academic Press, NY.Academic Press, NY.


Thank YouThank You

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