Download IUN-nodalida

Issues Under Negotiation
Staffan Larsson
Dept. of linguistics, Göteborg University
[email protected]
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)
GoDiS features
• 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)
control
DME
input
interpret
update
select
generate
output
Information State
database
lexicon
domain
knowledge
Sample GoDiS information state
AGENDA =
PRIVATE =
PLAN =
{ findout(?return) }
findout(?x.month(x))
findout(?x.class(x))
respond(?x.price(x))
BEL = { }
TMP = (same structure as SHARED)
SHARED =
dest(paris)
COM =
transport(plane)
task(get_price_info)
QUD = < x.origin(x) >
LM = { ask(sys, x.origin(x)) }
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.
2.
3.
4.
A
A
A
A
attends to B’s utterance
percieves B’s utterance
understands B’s utterance (grounding)
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:
S:
U:
S:
U:
flights to paris on september 13 please
there is one flight at 07:45 and one at 12:00
what airline is the 12:00 one
the 12:00 flight is an SAS flight
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 seminegotiative 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 nonnegotiable, 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))
B: OK, there’s one flight leaving at 07:45 and
one at 12:00
AGENDA =
PLAN =
PRIVATE =
{ findout(?x.sel_flight(x)) }
findout((?x. ccn(x))
book_ticket
BEL = {flight(f1),
dep_time(f1,0745), ... }
TMP = (same structure as SHARED)
IUN =
< ?x.sel_flight(x){ f1, f2 } >
SHARED =
COM =
dep_time(f1,0745),
dep_time(f2,1200)
dest(paris), ...
<>
LM = {propose(f1), propose(f2),
answer(dep_time(f1,07:40),...}
QUD =
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