Issues Under Negotiation

Staffan LarssonDept. of linguistics, Göteborg University

sl@ling.gu.se

SigDial, 15/7 2002

Overview

• background• GoDiS: issue-based dialogue management• Sidner: a formal account of negotiative

dialogue• problems with Sidner’s account• an alternative account based on Issues

Under Negotiation• example• summary

Background

• TRINDI project (1998-2000)– TrindiKit: a toolkit for building and

experimenting with dialogue systems– the information state approach– GoDiS: an experimental issue-based

dialogue system• inquiry-oriented dialogue (IOD): ask, answer• action-oriented dialogue (AOD): request, confirm

• SIRIDUS project (2000-2002)– extend GoDiS to handle action-oriented

dialogue and negotiative dialogue

Background

• Thesis: Issue-based dialogue management– basic issue-based dialogue management– grounding issues– addressing unraised issues– action-oriented and negotiative dialogue

• thesis and implementation available at – http://www.ling.gu.se/~sl/Thesis

background:The information state approach

– key concepts

• Information states represent information available to dialogue participants, at any given stage of the dialogue

• Dialogue moves trigger information state updates, formalised as information state update rules

• Update rules consist of conditions and operations on the information state

• Dialogue move engine updates the information state based on observed moves, and decides on next move(s)

• IOD, AOD• Information state based Ginzburg’s

notion of Questions Under Discussion (QUD)

• Dialogue plans to drive dialogue• Simpler than general reasoning and

planning• More versatile than frame-filling and

finite automata

GoDiS features

inputinter-pret

Information State

data-base

control

update selectgene-rate

output

lexicon domainknowledge

DME

PRIVATE = PLAN =

AGENDA = { findout(?x.month(x)) }

SHARED =

findout(?x.month(x))findout(?x.class(x))

consultDB(?x.price(x))

COM = dest(paris) transport(plane)

QUD = < ?x.dept(x) >LM = { ask(sys, x.dept(x)) }

BEL = { }

Sample GoDiS information state

ISSUES = < ?x.dept(x), ?x.price(x) >

Sidner: an artificial language for negotiation

• formal account of negotiative dialogue• “state of communication”

– beliefs (individual)– intentions– mutual beliefs– stack of open beliefs (OpenStack)– stack of rejected beliefs

• messages update state of communication– fits IS update approach

Sidner cont’d• agents transmit messages with propositional

contents– ProposeForAccept(PFA agt1 belief agt2)

• agt1 expresses belief to agt2, intending agt2 to accept belief

• belief is pushed on OpenStack

– Reject (RJ agt1 belief agt2)• agt1 does not believe belief• belief is popped from OpenStack and pushed on

RejectedStack

– Accept (AP agt1 belief agt2)• agt1 and agt2 now hold belief as a mutual belief• belief is popped from OpenStack

Sidner: counterproposals

• Counter (CO agt1 belief1 agt2 belief2): without rejecting belief1, agt1 offers belief2 to agt2

• analysed as two proposals– (PFA agt1 belief2 agt2)– (PFA agt1 (Supports belief2 (Not belief1))

• A counterproposal requires that the new proposal conflicts with a previous proposal

• In this way, Sidner can distinguish unrelated proposals from related proposals

A problem with counterproposals

• problems:– proposals of alternative solutions to same

problem are seen as counterproposals, i.e. as conflicting with previous proposals

• but often alternative proposals do not conflict with previous proposals (e.g. buying a CD)

– a proposal commits an agent to intending that the addressee accepts the counterproposal rather than previous proposals,

• but e.g. a travel agent is usually quite indifferent to which proposal is accepted

Sidner: application to travel agency dialogue

• All utterances (except acceptances and rejections) are seen as proposals

• example:– U: Hi, my name is NN [propose]– S: Hi, what can I do for you [accept, ...]

• Why is this counterintuitive?– a person’s name is usually not a negotiable

issue

Negotiation vs. acceptance

• Allwood, Clark: levels of communicative action – 1. A attends to B’s utterance– 2. A percieves B’s utterance– 3. A understands B’s utterance (grounding)– 4. A accepts or rejects B’s utterance

• Sidner and others sees negotiative dialogue as proposals and acceptance/rejections

• this means that all dialogue is negotiative

– all assertions (and questions, instructions etc.) are proposals

Negotiation vs. acceptance

• But some dialogues are negotiative in another sense,

–by explicitly containing discussions about different solutions to a problem, and finally deciding on one

–Negotiation in this sense is not Clark’s level 4

• proposals are dialogue moves on the same level as questions, assertions, instructions etc.

• There’s a difference between – accepting a proposal-move, and thereby adding a possible solution, and

– accepting a proposed alternative as the solution

Two senses of “negotiation”

• Negotiation in Sidner’s sense– A: Give me information about flights to Paris

[propose]– B(1): OK, let’s see... [accept]– B(2): Sorry, I can’t do that [reject]

• Negotiation in our sense– U: flights to Paris on september 13 please – S: there is one flight at 07:45 and one at 12:00

[propose two flights]– U: what airline is the 12:00 one [ask]– S: the 12:00 flight is an SAS flight [answer]– U: I’ll take the 12:00 flight please [accept flight]

Remedies

• distinguish utterance acceptance from “real” negotiation

• an account of counterproposals which can account for the fact that– a new proposal may concern the

same issue as a previous proposal,– without necessarily being a

counterproposal

Negotiativity

• Negotiation is a type of problem-solving • suggested characterisation of negotiation:

– DPs discuss several alternative solutions to some problem before choosing one of them

• Negotiation does not imply conflicting goals – perhaps not 100% correspondence to everyday use

of the word “negotiation”, but useful to keep collaborativity as a separate dimension from negotiation

– this is also common practice in mathematical game theory and political theory

Negotiation tasks• Some factors influencing negotiation

– distribution of information between DPs – distribution of decision rights: whether DPs must commit jointly

(e.g. Coconut) or one DP can make the comittment (e.g. flight booking)

• We’re initially trying to model negotiation in flight booking– sample dialogue

• U: flights to paris on september 13 please• S: there is one flight at 07:45 and one at 12:00• U: what airline is the 12:00 one• S: the 12:00 flight is an SAS flight• U: I’ll take the 12:00 flight please

– Sys provides alternatives, User makes the choice– Sys knows timetable, User knows when he wants to travel etc.

Degrees of negotiativity

• non-negotiative dialogue: only one alternative is discussed

• semi-negotiative dialogue: a new alternative can be introduced by altering parameters of the previous alternative, but previous alternatives are not retained

• negotiative dialogue: several alternatives can be introduced, and old alternatives are retained and can be returned to

Semi-negotiative dialogue

• Does not require keeping track of several alternatives

• Answers must be revisable (to some extent)

• Example of limited semi-negotiative dialogue– Swedish SJ system (Philips): ”Do you

want an earlier or later train?”

Issues Under Negotiation i (fully) negotiative dialogue• IUN is question e.g. what flight to

take• In an activity, some questions are

marked as negotiable issues– other questions are assumed to be

non-negotiable, e.g. the user’s name in a travel agency setting

– non-negotiable issues may become negotiable if an answer is rejected

Alternatives in negotiation• Each negotiable issue is associated with a set of

proposed answers– Pair(WhQuestion,Set(Answer)))

• Alternatives are possible answers to an IUN• a proposal has the effect of introducing a new

alternative to the Issue Under Negotiation• An IUN is resolved when an alternative is chosen by

the DP(s) having decision rights– if DP A has the decision right over Q, explicit indication of

acceptance from B is not necessary– if decision rights are shared, explicit acceptance by both is

(probably) needed – In some cases, the answer to IUN may consist of a subset of

the proposed alternatives (e.g. when buying CDs)

Negotiation in GoDiS

• currently, can only represent information about one flight at a time

• but we want to be able to – talk about several flights, – allowing the user to ask questions about them,

comparing them etc.– deciding on one of them, and then– getting price information / booking a flight

• (negotiation can occur in information-seeking dialogue; not only in collaborative planning)

Example• IUN is ?x.des_flight(x) (“which is the user’s

desired flight?”)• A: flight to paris, december 13

– answer(dest(paris)) etc.;

• B: OK, there’s one flight leaving at 07:45 and one at 12:00– propose(f1), propose(f2),– answer(dep_time(f1,07:45)), answer(dep_time(f2,12:00))

• ....• A: I’ll take the 07:45 one

– answer(des_flight(X), dep_time(X, 07:45)),– after contextual interpretation: answer(des_flight(f1))

PRIVATE =

PLAN =

AGENDA = { findout(?x.des_flight(x)) }

SHARED =

findout(?x. credit_card(x))book_ticket

COM = dept_time(f1,0745) dept_time(f2,1200)

dest(paris), ...

QUD = <> LM = {propose(f1), propose(f2),

answer(dept_time(f1,07:40),... }

BEL = {flight(f1), dept_time(f1,0745), ... }

ISSUES = < ?x.des_flight(x){ f1, f2 } >

B: OK, there’s one flight leaving at 07:45 and one at 12:00

Issues Under Negotiation: Summary

• negotiable issues modelled semantically as questions, and alternatives as answers

• negotiation of alternatives as opposed to accepting or rejecting utterance

• proposed alternatives can concern the same issue, without conflicting

• not all issues are negotiable: depends on the activity

• a formal account in line with the use of Questions Under Discussion in GoDiS

Future work

• implementation– soon!

• exploring negotiation in other domains• dealing with conflicting goals

– e.g. Castelfranchi et al 2000

• relation to discourse structure– Rosé et al 1995: “threads” (related to

alternatives)

CD dialogue

– U: Records by the Beach Boys– S: You can buy Pet Sounds, Today, or Surf’s

Up– U: Which is the cheapest?– S: Pet Sounds and Today are both 79:-,

Surf’s Up is 149:-– U: Hmm... I’ll get Pet Sounds and Today

Proposals and alternative-questions

• wh-question + proposals has same effect as asking alt-question– ”Do you want to travel in economy class or

business class?” [ask alt-q]– ”How do you want to travel? One option is

economy class. The other option is business class.” [ask wh-q; propose(economy), propose(business)]

• alternate representation of alt-q’s– {?P(a1), …, ?P(aN)}– ?x.P(x)-{a1, …, aN}– partial functions for format conversion

”Downshift”• original idea (Cohen 1978)

– ”gears” in dialogue: ”games per turn”• high gear = many latent subgames per turn

– originally used to describe shifting to e.g. referent identification subdialogues

– ”latent” referent identification game becomes manifest; c.f. finding answer to content-question

• extension to acceptance– If optimistic assumption of acceptance fails,

negotiation may ensue– latent acceptance game becomes manifest– this is where an issue assumed to be non-negotiable

turns becomes negotiable

sample dialogue

A: Where do you want to travel?B: Paris [answer(paris)]

– B optimistically assumes dest-city(paris) in SHARED.COM

A: Sorry, there are no flights to Paris. How about Marseille or Lyons?– question is reraised and is opened for

negotiation; two proposals added– ISSUES=<?x.dest-city(x)-{marseille, lyons,

paris}, …>

dialogue classification• types of dialogue

– inquiry-oriented: ask, answer– action-oriented: request, confirm

• properties of dialogue– grounding– mixed initiative (question accommodation etc.)– negotiation

• properties of application domain– distribution of information– distribution of decision rights– type of result (complex or simple)

• Both AOD and IOD can be negotiative– in a flight information service, the user does not become obliged to

fly anywhere; so it’s IOD– but several different flights may be discussed

Argumentative (non-collaborative?) negotiative dialogue

• argumentation for/against alternatives (not just exchanging information about them)

• requires dialogue moves for argumentation (rhetorical moves)

• mostly relevant when DPs must decide something jointly

• need to represent DP’s stance towards alternatives + arguments for and against

Negotiation does not necessarily concern future actions

• S: What’s the name of Jim’s sister?• U: Sue• S: Are you sure? I think it was Janeissues = <?x.name_of(jims_sister, x)-{sue,

jane}>

• U: Isn’t Jane the name of Jack’s sister?

• S: Oh right, Sue then.

an optimistic approach to utterance acceptance

• DPs assume their utterances and moves are accepted (and integrated into SHARED)– If A asks a question with content Q, A will put Q

topmost on SHARED.QUD

• If addresse indicates rejection, backtrack– using the PRIVATE.TMP field

• No need to indicate acceptance explicitly; it is assumed

• The alternative is a pessimistic approach– If A asks a question with content Q, A will wait for an

acceptance (implicit or explicit) before putting Q on top of QUD