Miscommunication WorkshopQMUL, London, January 26, 2006

Staffan LarssonGöteborg University

sl@ling.gu.se

Semantic plasticity through feedback and accommodation in dialogue

(Meaning through Miscommunication)

Overview

• Introduction• Negotiation, feedback,

accommodation• Semantic plasticity• Meaning accommodation• Conclusions

Introduction

Questions

• What goes on in dialogue?– Information exchange, but also:– Explicit and implicit negotiation of meaning (and other

aspects of language)– Which mechanisms govern these processes?– How are these processes related?

• What is meaning?– Is meaning private or social? In what sense?– How is meaning and use of language related?– What is the role of formal representations in a theory of meaning?– What is the role of subsymbolic cognition in a theory of meaning?

Two kinds of coordination in dialogue

• Information sharing– Sharing of symbolically / linguistically represented information– Grounding (updating common ground)

• Coordination of linguistic resources (language system)– Semantic change and adaptation (& linguistic change in general)– Adaptation of linguistic resources to activity or situation – Adaptation of linguistic resources to specific partner– Ad-hoc adaptation to a specific conversation– Long-term changes in language over time

• Linguistic coordination is necessary for information sharing– Establishes shared meaning of linguistic constructs used to share

information

Work on dynamics of information sharing

• Starting point: language games (Wittgenstein 1953) • Formal descriptions of language games

– Dialogue grammars (Sinclair & Coulthard)– Dialogue games as finite state automata (Lewin et al)

• Game-theoretical accounts– Carlson 1983– Jaeger et al (recent)

• … and lots more…• Research on formal and computational accounts of dialogue games

(SemDial workshop series 1997-); TRINDI and later projects• Dialogue games as Information State Updates

– In terms of sequences of dialogue moves– Moves trigger updates to a Dialogue Gameboard (which is part of a

more inclusive Information State)• Example: Issue-Based Dialogue Management (Larsson, Ginzburg)

Work on dynamics of language system

• Halliday – Meaning potentials, adapting linguistic resources to specific activities

• Clark– Creative language use: creating verbs from nouns

• Brennan– Conceptual pacts, lexical entrainment

• Healey– Emergence of shared vocabularies in groups vs. across groups

• Cutler et al– Phonetic plasticity

• Pickering & Garrod– Alignment of multiple levels in dialogue

• Steels et al– Emergence of shared categories through social and embodied linguistic

learning in robots

Common theme in work on dynamics of language

• How new vocabulary emerges • How words acquire or change meaning

through social linguistic interaction

• Additional themes– Language is activity-specific (dialogue games)– Language and embodiment

Symbolic and nonsynbolic/subsymbolic

• According to Dreyfus, Brooks and others, cognition is not based on symbolic representations– Dreyfus claims that human language understanding

relies on a background which cannot be represented as a set of facts

• Still, human language is the prototypical symbol system so linguistic cognition must involve symbolic representations

• How does symbolic and nonsymbolic cognition interact in language understanding and dialogue in general?

Some theoretical issues

• Give accounts and models of– Individual usage dispositions and how they are

updated – How social meaning is related to usage dispositions– How meaning is negotiated, tacitly and explicitly, and

how this relates to updates of usage dispositions• Dialogue games for meaning negotiation• Tacit negotiation through feedback and accommodation

– Integrate account of semantic dynamics with existing accounts of dynamics of symbolic (linguistic) information updates, into a general account of alignment/coordination in dialogue

Negotiation, feedback, accommodation

Three important processes of coordination in dialogue • Explicit negotiation

– “Negotiation” used here in weak sense of “reaching a joint decision” (may be antagonistic or cooperative)

– E.g. ostensive language games (Steels & Belpaeme 2005: “the guessing game”), explicit verbal definitions

• Feedback– Signalling perception, understanding, acceptance– Signalling failure to perceive or understand; clarification;

rejection– Guides coordination of DGB (Grounding)– >Also: guides coordination of language use

• Accommodation: Adapting to the behaviour of other DPs – Adapting to presuppositions (adapting the DGB)– >Also: adapting to language use (adapting linguistic resources)

Accommodation• Conversational scoreboard

– Dialogue gameboard (DGB)– (Part of) Common Ground (CG)– (Shared part of) Information State (IS)

• Lewis (1979): – Dialogue tends to evolve in a way that makes any move count as

correct play– “If someone says something at t which requires X to be in the

conversational scoreboard, and X is not in the scoreboard at t, then (under certain conditions) X will become part of the scoreboard at t”

• Has been applied to referents and propositions, as parts of the conversational scoreboard– E.g. “Bo snores” or “My cat is hungry” presupposes referent in DGB– If no matching referent in DGB, hearer may ask clarification question– but only after failure to accommodate

Issue-based Dialogue Management

• (Larsson, Ginzburg)• DGB includes a stack of Questions Under

Discussion (QUD)• Answers require a matching question before

they can be accepted and integrated

RULE: integrateAnswerPRE: in( $/SHARED/LU/MOVES, answer(A) )

fst( $/SHARED/QUD, Q )$DOMAIN :: relevant( A, Q )

EFF: ! $DOMAIN: combine( Q, A, P )add( /SHARED/COM, P )

Typical human-human dialogue

S(alesman), C(ustomer)

S: hi

C: flight to paris

S: when do you want to travel?

C: april, as cheap as possible

Typical human-human dialogue

S(alesman), C(ustomer)

S: hi

C: flight to paris

S: when do you want to travel?

C: april, as cheap as possible

How do you want to travel?

Where do you want to travel?

What price range?

Question accommodation

• If questions are part of the DGB, they too can be accommodated

• If the latest move was an answer, and there is an matching question which is relevant in the activity at hand, then– put that question on QUD

Coordination and accommodation

• “... someone says something at t which requires X to be in the conversational scoreboard, and X is not in the scoreboard at t...”

• This may indicate a case of lack of coordination– but may also be used as a strategy for conveying

implicit information (Grice)• In any case, accommodation can be used to

adjust to some presupposition of what is shared

Feedback in dialogue

• Feedback: signals for achieving coordination (alignment, grounding) on several levels of action (Allwood, Clark)– Contact / attention: +/-– Perception: +/-– Understanding: +/-/?– Reaction: accepting and rejecting utterances

• The hearer can react to whole utterances or sentences, or to some part of an utterance – A word, a phrase, a grammatical construct, or in

general any linguistic construct– Example: Clarification Requests (Ginzburg)

Grounding

• ”To ground a thing … is to establish it as part of common ground well enough for current purposes.” (Clark)

• Common Ground includes– general facts about the world (commonsense knowledge)– More specific facts about the world (e.g. facts about history)– facts about words (dog can mean ”canine animal”)– and more

• Henceforth, we will use grounding in a more limited sense– The process of adding information to the ”Dialogue

Gameboard” (DGB) or Conversational Scoreboard

Semantic plasticity

Structuralism

• The sign relation, i.e. the connection between words (linguistic form) and concepts is arbitrary

• The way that linguistic material is divided into words is arbitrary

• The way that the world is divided into concepts is arbitrary

• Focus on study of language as a structure (langue); the concrete use of language (parole) assumed too unruly for scientific study

Poststructuralism

• Langue is continuously being affected by parole• Words change their meanings over time as a result of

language use• If or concepts determine how we understand the world...• Concrete language use changes our understanding of

the world• Communication is not (just) transmission of information

• Science studies, Critical Discourse Analysis & related disciplines study how people fight over the use of certain words; “man”, “gender”, “gene”, “terrorism”, …

Phonetic plasticity

• Cutler, McQueen, Norris (2005)– ACL paper

• Experiment:– Ambiguous phoneme /?/ between /f/ and /s/– Group A hears words where /?/ replaces /f/,

e.g. ”carafe”– Group B hears words where /?/ replaces /s/

• Result– For group A, the /f/ category became more inclusive

(tested by phoneme categorisation)– For group B, the /s/ category became more inclusive– Exposure to /?/ in non-word context had no effect– Effect generalised to new words, and thus facilitates

word recognition

Semantic plasticity

• As with phonemes, semantic categories can (presumably) gradually expand, contract, and shift

Kinds of semantic plasticity

• Semantic systems exist on several levels– National– Regional– Domain, activity, language game– Personal (idiosyncratic)– Particular interactions (dialogues)

• Semantic system can be adapted– Example: “the one with the handle going across”: map “handle” to certain shape

on card (Brennan)– to a new activity or domain– to a certain individual (who has an idiosyncractic way of using some concept)– to a certain interaction (ad-hoc)

• Associated issue:– When & to what extent does “idiosyncratic” usage of some word in a single dialogue affect its meaning in

general? • Plasticity vs. elasticity

– Indeed, are there “meanings in general” which are adapted to specific activities or are meanings just borrowed from other (equally specific) activities?

• Meaning emerges from a multitude of interactions where the DPs of a linguistic community shape each other’s usage dispositions

• A language-user A observes some linguistic construct c being used in a set of situations Sc (situational collocation for c)

• A generalises over Sc; this generalisation we call the usage disposition [c]

• The way [c] is updated after a use depends on the feedback given by other DPs– A: “Alignment is automatic”– B; “Uhuh” / “I agree” / “Automatic?” / “No way!” / “Eh?” / ...– [“automatic”] may get updated for A or B or both

Sketch of a formal general account of semantic plasticity

Usage dispositions

• Instead of modelling semantic plasticity directly, we will model usage dispositions– Private (“in the head”), but socially conditioned– Do not completely determine usage, but affects it

• Dispositions are affected by feedback• The usage-dispositions of the members of a

linguistic community must be sufficiently similar to allow for coordinated behaviour

• The model will allow for creative language use• The following is an abstract “skeleton” account

that can be filled out in may different ways

Situational collocation

• Abstractly, each individual A can be associated with a situational collocation ScA – Contains the situations in which A has observed c to

be used (including uses by A)

– ScA = { s | c was observed by A to be used in situation s }

• We won’t say more about what a situation is here; can be fliled out in various ways to include e.g.– Linguistic context– Referential context– “Connotational” aspects

Successful and unsuccessful uses

• Consider a situation where c is used in s, and c is addressed to B.

• B can understand c or fail to do so• Provided B understands (or thinks he understands), B

can choose to accept or reject c• In the following, we will (for the most part) restrict

feedback to – acceptance (and understanding)– negative understanding (and no acceptance)– positive understanding, rejection

• Successful use: understood and accepted• Unsuccessful use: not understood, or rejected

Usage dispositions: more

• Presumably, an individual A somehow generalises over situational collocations– (Alternatively, remember completely all situations where each constructs

was used)• We refer to this generalisation as A's usage disposition for c• An agent A’s usage disposition for c, written as [c]A, is a function of

the situational collocation for c – [c]A = fdisp-A(ScA)

• Related points:– This function may capture any aspects of the situation that are relevant to language use;

physical, biological, psychological, sociological, linguistic– To handle ambiguity, this function should allow for differentiated generalisations over subsets

of ScA– Does the generalisation function differ

• Between speakers?• Between linguistic categories (nouns, verbs, grammar rules, …)?

Judging appropriateness• We assume that something like “estimated degree of

appropriateness” or “consistency with previous uses” plays a role in language use

• Appropriateness of using c in s is a function of the usage disposition for c, and s– appr(c, s)A = fappr([c]A,s) = fappr(fdisp(ScA), s)

• In a simple case, we can model fappr with a boolean function (either appropriate or non-appropriate)– Or it could be a numerical value, e.g. between 0 and 1

• Related points– This is not meant to imply a conscious judgement… – … nor that it is relevant or even possible to say whether the estimation of appropriateness is

“correct”– May be used to model some notion of “linguistic intuition” governing own language use

including how one gives feedback

Indeterminacy

• Upon hearing c in new situation s, A’s reaction (the kind of feedback A gives) partly depends on [c]– But A’s behaviour is not determined by [c], or even

Appr(s,c)– This means that A can understand and accept uses of

c that deviate from [c]• A’s own future uses of c are partly determined

by [c]– Again, A’s own use of c is not determined by [c], or

even Appr(s,c)– A can use c in ways that deviate from [c]

Disposition updates• If follows from the definition of dispositions that whenever a

construct c is used, Sc will be extended, and so the usage-disposition [c] may change

• This is a disposition update– Disposition reinforcement

• This use of c is consistent with usage disposition, i.e., c is appropriate in s • No drastic change; previous disposition is reinforced

– Disposition revision• This use of c is non consistent with usage disposition• More or less drastic change of meaning; previous meaning is revised

• Related points– Arguably, all language uses are creative since all situations are different

• But intuitively, some uses are more creative than others• To what extent can we distinguish revision from reinforcement?

– Are updates continuous or discrete• Depends on the kind of linguistic construct?• Scalar terms, e.g. colour terms appear to be continuous

The usage equation

• use(c, s)A = fuse( fappr(fdisp(ScA), s), X )• What does this mean?• Whether A uses c in s depends on

– s: The current situation– ScA: Situational collocation for c - previous situations where c

has been used, in A’s experience– fdisp: The way A generalises over these– fappr: The way A uses this generalisation do determine the

appropriateness of c in s– Any additional factors X – the ways in which these, in conjunction with the appropriateness

judgement, affect whether c is actually used (fuse)

Possible outcomes of using c in s

Speaker appropriate (conservative use)appr(c, s)A = true

Speaker non-appropriate(creative use) appr(c, s) A = false

Hearerappropriateappr(c, s)B = true

Successful FB(c, s)B = accept

Default Case reinforce [c]A, [c]B

Successful FB(c, s)B = accept

Unnoticed creativity revise [c]A, reinforce [c]B

Unsuccessful Unsuccessful

HearerNon-appropr.appr(c, s)B =

false

SuccessfulAccommodated

Conservative Use reinforce [c]A, revise [c]B

SuccessfulAccommodated Creative Use revise [c]A and [c]B

Unsuccessful FB(c, s)B = reject

Uncovered discrepancy ? (negotiation)

Unsuccessful FB(c, s)B = reject

Failed Creative Use reinforce [c]A and [c]B

From usage dispositions to meaning

• The meaning of a construct c in a linguistic community L emerges from the coordinated use of c by the members of L– Meaning is inherently social, and arises out of

coordinated behaviour in a linguistic community– In interaction, members of a community “mould” each

others’ usage dispositions by giving feedback and accommodating usage

– This keeps language use sufficiently coordinated for meaning to arise

• By modelling plasticity of usage dispositions, we indirectly model semantic plasticity

Meaning accommodation

Possible outcomes of using c in s

Speaker appropriate (conservative use)appr(c, s)A = true

Speaker non-appropriate(creative use) appr(c, s) A = false

Hearerappropriateappr(c, s)B = true

Successful FB(c, s)B = accept

Default Case reinforce [c]A, [c]B

Successful FB(c, s)B = accept

Unnoticed creativity revise [c]A, reinforce [c]B

Unsuccessful?

Unsuccessful?

HearerNon-appropr.appr(c, s)B =

false

SuccessfulAccommodated

Conservative Use reinforce [c]A, revise [c]B

SuccessfulAccommodated Creative Use revise [c]A and [c]B

Unsuccessful FB(c, s)B = reject

Uncovered discrepancy ? (negotiation)

Unsuccessful FB(c, s)B = reject

Failed Creative Use reinforce [c]A and [c]B

Meaning accommodation

• For each construct used in an U, the addressee in a dialogue is (usually) expected to react if he thinks a construct in U was incomprehensible or inappropriately used

• If a breakdown occurs during interpretation of U by B, it may be due to a mismatch between the situation in which c was being used by A, and B’s usage disposition for c

• The addressee B may now – reject this use of c explicitly: negative feedback on understanding or

acceptance level– or quietly alter B’s usage disposition for c so that c can be counted as

appropriate after all. • The latter process we may call usage accommodation, or

meaning accommodation– This extends the notion of accommodation beyond the DGB, to

include the language system

Two variants of meaning accommodation

• Accommodated creative use– Speaker non-appropriate, Hearer non-appropriate, successful– New use not “appropriate” according to speaker but speaker tries it

anyway– revise [c]A and [c]B

• Accommodated conservative use– Speaker appropriate, Hearer non-appropriate, successful– Not really creative since the speaker followed her appropriateness

judgement, but hearer had not heard that use before– reinforce [c]A, revise [c]B

• Example (of either of the above)– (in 1991 or so)– A: What are you doing?– B: I’m surfing the web– A: ... Ah, OK.

Latent subgames and “gears” in dialogue

• Cohen (1978), Severinsson-Eklundh (1983)• Dialogue involves “latent subgames” or “tacit moves” that can become

explicit if necessary• Example: referent identification subgame, perception subgame

– A: Pick up the red one– B: (hears “pick up the red one”) – B: (identifies red object; there are two but only one has been discussed previously) – B: (picks up red object)

– A: Pick up the red one– B: (hears “pick up the red one”) – B: Do you mean this one? (points to x)– A: No, this one (points to y)– B: (picks up red object)

– A: Pick up the red one– B: Pardon?– A: Pick up the red one– B: …

Accommodation as tacit negotiation

• Meaning accommmodation can be seen as tacit negotiation of meaning

• When dialogue proceeds smoothly, speakers shift to high gear and assume that latent subgames will succeed– Optimistic strategy– Tacit moves / games

• When problems (breakdowns) occur, participants shift into low gear and give explicit feedback, request confirmation, etc.– Cautious strategy– Latent subgames are played out explicitly

• Explicit negotiation can often be regarded as occurring in “low gear”• Accommodation can be seen as a tacit dialogue move (or game),

which replaces an explicit subgame of negotiation

Explicit negotiation vs. accommodation

• Meaning can change as a result of explicit negotiation or accommodation

• Explicit negotiation – Hearer detects problem and initiates negotiation subgame to

resolve it• Accommodation

– Hearer detects has problem understanding or finds utterance otherwise inappropriate or problematic, but nevertheless is able to adapt to the situation and proceed with the interaction

– Commonsense background and general redundancy in linguistic interaction enables efficient tacit negotiation through accommodation

Conclusions

Coordination of meaning through miscommunication• “Perfect communication”

– Perception, understanding and agreement are unproblematic– No negotiation, feedback or accommodation is needed

• “Miscommunication”– Perception, understanding and agreement are fallible– Feedback is needed to monitor success– Accommodation is needed for efficiently adapting to differences in DGB

and language system– These mechanisms enable coordination of meaning through the

interactive adaptation of usage dispositions• Miscommunication is thus the very basis for linguistic plasticity and

adaptation• If there was no miscommunication, language would be static and

unadaptable – Unless changes where instantaneous and universal, which does not

seem very plausible

Summary• Three types of mechanisms for dealing with miscommunication

– Explicit negotiation– Feedback– Accommodation

• … enable coordination of...– Dialogue Gameboard updates– Dynamics of semantic system (semantic plasticity)

• Coordination of DGB presupposes a sufficiently coordinated language system

• In “low gear”, explicit negotiation of usage / meaning is played out explicitly• In dialogue in “high gear”, accommodation enables adaptation of usage

dispositions (and thus coordination of usage)

• Meaning emerges and changes not only as a result of explicit negotiation, but also as a “side-effect” of tacitly resolving problems in information sharing

Additional material

future work

Components of a “Socio-somatic” semantics• Semantic plasticity

– Plasticity of individual usage dispositions– Relation usage dispositions – social meaning– Emergent social dynamics of language

• Negotiation of meaning– How meaning changes as a result of linguistic interaction (dialogue)– Tacit negotiation and “miscommunication” – Explicit negotiation:

• Dialogue games for symbolic information sharing in terms of DGB updates– Presupposes a shared language system

• Interplay between symbolic and subsymbolic in cognition and learning– Complementary properties of symbolic and subsymbolic cognition– Interaction between (symbolic) Dialogue Gameboard and (subsymbolic)

background in language use and interpretation– Embodiment of (1) language system and (2) “facts”– Consequences for the possibility of language understanding in computers

Study H-H dialogue

• To what extent is novel language used consciously noticed?– How novel does it have to be?

• To what extent is meaning explicitly negotiated, and to what extent does it happen implicitly?– Presumably depends on activity and speaker

competence (c.f. second language learners)• How can we identify cases of accommodation?

– If we know there is no pre-coordinated vocabulary (as in Healey corpus)

Computational

• Extend dialogue management (IBDM) and dialogue system (GoDiS) with mechanisms for coordination of language system– Set up meaning coordination experiments with complex dialogue

management• Implement meaning accommodation & tacit negotiation

– Semantic plasticity as side-effect rather than main activity• Specifying further formal / computational instantiations of

the general account, incl. relating previous research– Steels et al– Latent Semantic Indexing– Other machine learning methods

General

• Explicitly relate computational models and psycholinguistic testing (cf. Healey 1997)

• Extend account to linguistic plasticity in general

• Compositionality• Relate to “traditional” semantic theories• Can there be meanings without pre-given

semantic features? If not, where do they come from?

SSS is interdisciplinary• General linguistics

– Meaning potentials, adapting linguistic resources to specific activities (Halliday)– Creative language use: verbs from nouns (Clark)– Semantic plasticity in relation to plasticity of language generally– Intra-system dynamics of meaning

• Computational linguistics– Emergence of shared categories through social and embodied linguistic learning in robots (Steels et al)– Latent Semantic Indexing and related methods of machine learning

• Psycholinguistics– Emergence of shared vocabularies (Brennan, Healey)– Plasticity in language, e.g. phonology– Mechanisms of generalisation and adaptation in human linguistic interaction

• Sociolinguistics– Emergence of linguistic subcommunities based on social networks

• Neurolinguistics– Neural basis for individual usage dispositions– (Neural basis for symbolic cognition)– Interaction between symbolic and subsymbolic cognitions

• Historical linguistics• Evolution of language• Philosophy of language

– Wittgenstein: meaning is use in specific language games– “Kripke’s Wittgenstein”: impossibility of a private language– Critiques of the possibility of language understanding in computers (Dreyfus)

• Critical Discourse analysis– Antagonistic and rhetoric uses of semantic plasticity

Dealing with divergence

Dealing with divergence• Interplay between DGB and language system• Divergence = lack of coordination• When an utterance is not understood or accepted, this may be due

either to – diverging beliefs (disagreement about “facts”), – diverging meanings (usage)– or both

• It is sometimes necessary to coordinate meanings before one can even figure out whether there is a disagreement– If the semantic systems are not sufficiently coordinated, there is no way of

telling whether one disagrees about the facts• In practice, the distinction is not so clear-cut

– (Even though disagreement about beliefs analytically presupposes coordination of meanings, convergence w r t registers and beliefs can proceed in parallel (but not independently))

• Accommodation and feedback can concern either DGB, semantic system, or a little of both

• A: “I want to fake a letter”• B: “Fake?”

• “Was it really FAKE that you wanted to do?”– questioning fact; it’s somehow inappropriate to (want to) fake a

letter– diverging beliefs (values?)– alternatively: accommodate (provisionally commit for the

purpouse of of discussion) that it’s OK to fake a letter• “What do you mean by fake?”

– questioning use; it makes no sense to use “fake” in this situation– diverging use– alternatively: if B can figure out what “fake” means here,

accommodate this use

Relation to Steels & Belpaeme 2005

Steels et al

• Steels & Belpaeme 2005• Investigate the effect of social linguistic

interaction on learning and coordination of colour categories

• Robot agents play a language game of referring to and pointing to colour samples

• Language system of individual agent– Connection word – category – For each category, a neural net that responds to

sensory data

• S&B 2005: A case of semantic plasticity– Categories are updated as a result of language use

• Meaning negotiation in S&B– Explicit and cooperative negotiation– Assymmetry w r t roles within each game; one is “teacher”, other is

“learner”– Language game of guessing and ostensive definition

• Situation, as perceived by agents– A set of objects, where one is the topic object– Objects represented by colour only (no shape)

• Functions– fdisp: Neural network, prototype with fuzzy borders– fappr: a word is appropriate if related category network scores highest

when applied to sensory data– used when appropriate give fappr + when indicated by guessing game

“The guessing game”• Example of dialogue game for explicit negotiation of meaning (Steels & Belpaeme

2005)• Overt and tacit moves• Speaker identifies topic ot (private “discrimination game”) and finds appropriate word form f• Speaker says “f”• Hearer looks up f

– If f is unknown, • “game fails” (H gives negative understanding feedback?)• S points to topic ot • H tries to discriminate ot from context; if successful, updates link between f and

category corresponding to ot – ELSE (if f is known),

• H tries to identify object associated with f in the context• H points to the assumed correct object o• If o = ot,

• game is successful• ELSE

• S points to ot• H adapts categories and lexicon

Guessing game as FSA

S: (points to topic)

S: fS: fb-acc-pos

H: fb-und-neg

H: (points to assumed topic)

S: (points to topic)

Accommodation instead of guessing

• Speaker identifies topic ot (private “discrimination game”) and finds appropriate word form f

• Speaker says “f”• Hearer looks up f

– If f is unknown, • H tries to use contextual information and discrimination

facilities to figure out which object o that S probably meant• if successful, updates link between f and category

corresponding to o– ELSE (if f is known),

• H tries to identify object associated with f in the context• H adapts categories and lexicon

S: “f”