CS 182 Sections 103 - 104 slides created by Eva Mok ([email protected])[email protected] modified by JGM March 22, 2006.

CS 182Sections 103 - 104

slides created by Eva Mok ([email protected])

modified by JGM

March 22, 2006

The Last Stretch

Cognition and Language

Computation

Structured Connectionism

Computational Neurobiology

Biology

MidtermQuiz Finals

Neural Development

Triangle Nodes

Neural Net & Learning

Spatial Relation

Motor Control Metaphor

SHRUTI

Grammar

abst

ract

ion

Regier Model

Bailey Model

Narayanan Model

Chang Model

Visual System

Psycholinguistics Experiments

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

Bailey’s VerbLearn Model

• 3 Levels of representation

1. cognitive: words, concepts

2. computational: f-structs, x-schemas

3. connectionist: structured models, learning rules

• Input: labeled hand motions (f-structs)

• learning:

1. the correct number of senses for each verb

2. the relevant features in each sense, and

3. the probability distributions on each included feature

• execution: perform a hand motion based on a label

Computational Details

• complexity of model + ability to explain data

• maximum a posteriori (MAP) hypothesis

)|( argmax DmPm

rule Bayes'by )()|( argmax mPmDPm

how likely is the data given this model?

penalize complex models – those with too many word senses

wants the best model given data

schema elbow jnt posture accel

slide extend palm 6

schema elbow jnt posture accel

slide extend palm 8

schema elbow jnt posture accel

slide 0.9 extend 0.9 palm 0.9 [6]

data #1

data #2

data #3

data #4

schema elbow jnt posture accel

depress 0.9

fixed 0.9 index 0.9 [2]

schema elbow jnt posture accel

slide 0.9 extend 0.9 palm 0.9 [6 - 8]

schema elbow jnt posture

slide 0.9 extend 0.9 palm 0.7

grasp 0.3

schema elbow jnt posture accel

depress fixed index 2

schema elbow jnt posture accel

slide extend grasp 2

Limitations of Bailey’s model

an instance of recruitment learning (1-shot)

embodied (motor control schemas)

learns words and carries out action

the label contains just the verb

assumes that the labels are mostly correct

no grammar

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

Aspect

• Aspect is different from tense in that it deals with the temporal structure of events

• Viewpoints

– looking at the same event at different granularity

– He was walking / He has walked / He walks

• Phases of Events

– zooming in at a level and focusing on a stage in an event

– He is about to walk / He finished walking

• Inherent Aspect

– perfective / imperfective (telic / atelic)

– He is walking / He is tapping his finger

Some linguistics theories on Inherent Aspect

• Zeno Vendler (1957)’s distinction on state, activity, accomplishment, achievement

stative

Verbal predicates

dynamic

atelic atelic telic

protracted instantaneousknowresemble

runswim

write a letterrun a mile

jumprecognizestate activity

accomplishment achievement

FYI:telic = boundedatelic = unboundedpunctual = instantaneous

Controller X-Schema• The controller x-schema is meant to capture the generic structure of events.

• Aspect therefore marks (or profiles) certain states or transitions.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

The car is on the verge of falling into the ditch.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

FALL

He stumbled on the uneven road.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

WALK

She cancelled her trip to Paris.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

TRAVEL

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

X-Schema Embedding

You can ‘blow up’ any state or transition into a lower level x-schema, allowing embedding

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

readystart

ongoingfinish

done

He is almost done talking.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

readystart

ongoingfinish

done

They are getting ready to continue their journey across the desert.

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

readystart

ongoingfinish

done

She smokes. (habitual reading)

readystart

ongoingfinish

done

iterateabortcancelled

interrupt resume

suspended

readystart

ongoingfinish

done

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

Mapping down to the time line

• we can use Reichenbach’s system to map the controller X-schema down to a time line and get tenses

S R E

readystart

ongoingfinish

done

Speech Time (S)

Reference Time (R)

Event Time (E)

He is talking

S

R

E

readystart

ongoingfinish

done

He has talked

S

R

E

readystart

ongoingfinish

done

He will have talked

S R E

readystart

ongoingfinish

done

He would have talked...

• … by the time the bell rang.

• … if you had not shushed him.

• okay this is getting complicated

• interaction with modals like would

• could be a strictly past reading (case 1)

• possibly a counterfactual (case 2)

Not much of a stretch…

to get to metaphorical sentences like this:

The US Economy is on the verge of falling back into recession after moving forward on an anaemic recovery.

• You would just need to map from this physical domain (source domain) to the say, economics (target domain)

• the Event Structure Metaphor is exactly the general mapping from motion to changes, locations to states

• and then you need some domain specific mappings

• more on that in lecture…

Quiz

• How does Bailey use multiple levels of representation to learn different senses of verbs?

• What’s the difference between aspect and tense?

• What’s X-schema embedding? Give an example where embedding is necessary.

• How can Reichenbach’s system be used with X-schemas? When does this system break down?

1. What does the prefix affix tree look like for the following sentences:

– eat them here or there

– eat them anywhere

2. What does the affix tree look like after the best prefix merge?

Affix Trees

• Data structures that help you figure out what merges are possible

• Each node in the tree represents a symbol, either terminal or non-terminal (we call that the “affix” in the code)

• Prefix Tree

• Suffix Tree

Prefix Tree

r1: S eat them here or therer2: S eat them anywhere

eat

them

here

or

there

r1

r1

r1

r1

r1

r2

anywhere

r2

r2

Sr1 r2

Prefix Merge

r3: S eat them X1r4: X1 here or therer5: X1 anywhere

eat

them

r3

r3

S

r3

here

or

there

r4

r4

r4

anywhere r5

X1

X1r3

r4 r5

Have a good Spring Break!!!