Issues Under Negotiation Staffan Larsson Dept. of linguistics, Göteborg University NoDaLiDa, May 2001

Overview background 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 –TrindiKit: a toolkit for building and experimenting with dialogue systems –the information state approach –GoDiS: an experimental dialogue system simple information-seeking dialogue SIRIDUS project –extend GoDiS to handle action-oriented dialogue and negotiative dialogue

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)

information-seeking dialogue 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 Has been extended to handle instructional dialogue Also being extended to handle negotiative dialogue (SIRIDUS) GoDiS features

input inter- pret Information State data- base control updateselect gene- rate output lexicon domain knowledge DME

PRIVATE =PLAN = AGENDA = { findout(?return) } SHARED = findout(? x.month(x)) findout(? x.class(x)) respond(? x.price(x)) COM = dest(paris) transport(plane) task(get_price_info) QUD = LM = { ask(sys, x.origin(x)) } BEL = { } TMP = (same structure as SHARED) Sample GoDiS information state

Problem with current GoDiS 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, –deciding on one of them, and then –getting price information / booking a flight Requires negotiation

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

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 understanding and acceptance –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: I’m going to Paris[propose P] –B(1): OK, let’s see... [accept P] –B(2): Sorry, we only handle trips within Sweden [reject P] 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 responsibility: 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 Each IUN is associated with a set of proposed answers –Needs a new IS field: SHARED.IUN of type assocset(question,set(answer))

Alternatives in negotiation 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 decided on, i.e. when an answer to it is accepted In some cases, the answer to IUN may consist of a set of alternatives (e.g. when buying CDs)

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

Example IUN is ?x.sel_flight(x) (“which is the chosen 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(sel_flight(X), dep_time(X, 07:45)), –after contextual interpretation: answer(sel_flight(f1))

PRIVATE = PLAN = AGENDA = { findout(? x.sel_flight(x)) } SHARED = findout((? x. ccn(x)) book_ticket COM = dep_time(f1,0745), dep_time(f2,1200)  dest(paris),... QUD = <> LM = {propose(f1), propose(f2), answer(dep_time(f1,07:40),...} BEL = { flight(f1), dep_time(f1,0745),... } TMP = (same structure as SHARED) IUN = B: OK, there’s one flight leaving at 07:45 and one at 12:00

Issues Under Negotiation: Summary 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 exploring negotiation in other domains relating IUN to global QUD; are they both needed? dealing with conflicting goals

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