Sidner’s artificial
negotiation language
Sidner: an artificial discourse
language for collaborative
negotiation
• Formal account of negotiative
dialogue
• negotiation for Sidner
– ...
• Has been applied to a dialogue
from the AMEX corpus
Sider: basic concepts
• state of communication
–
–
–
–
–
beliefs (individual)
intentions
mutual beliefs
stack of open beliefs (OpenStack)
stack of rejected beliefs (RejectedStack)
• messages
– agents (a,b) transmit messages with
propositional contents (p)
– semantics of messages
• given in terms of postconditions on the state of
communication
messages
• primitive message types
– ProposeForAccept PFA(a,p,b)
• a expresses p to b, intending b to accept p
• When acknowledged, p is pushed on OpenStack
– Reject RJ(a,p,b)
• a does not believe p
• p is popped from OpenStack and pushed on
RejectedStack
– Accept AP(a,p,b)
• a and b now hold p as a mutual belief
• p is popped from OpenStack
– RetractProposal RP(a,b,p)
• a retracts his proposal p
other messages
• Derived messages
– Counter: CO(a,p,b,q)
• a counters b’s proposal of p with q
– AcceptOtherProp: AOP(a,b,p,q)
• a accepts b’s proposal of q and rejects his own
proposal p
– ProposeReplace: PR(a,b,p,q)
• a proposes p and rejects b’s proposal of q
– ProposeAct: PA(a,b,d,c)
• a proposes action d in context c
• Acknowledgement messages
– AckReceipt, AckReject, AckRejectedProp
Sample definition
• ProposeForAccept: PFA(a,p,b)
– BEL(a,p)
– INT(a,Achieve(a, BEL(b,p)))
– BEL(a,Communicated(a,b,p))
• AckReceipt: AR(a,p,b)
–
–
–
–
MB(a,b,BEL(b,p))
MB(a,b,INT(a,Achieve(a,BEL(b,p)))
MB(a,b,Communicated(a,b,p))
p is pushed on OpenStack
Analysis of questions
• Question = proposal that agent
should perform an action
• Example
– “Did John come?”
– PFA(a,Should-Do(b,Tellif(b,
‘(john did come)))
• In what sense are questions
proposals?
AMEX dialogue
0 BC My name is B C and I would like to plan a trip
1 TA and the date you need to leave?
...
19 TA there is one on United that leaves Oakland at
eleven thirty p.m. and arrives Chicago five twenty five
a.m.
20 BC so that's a two hour hold there
21 TA yes
22 BC waiting for that flight ok any others?
23 TA uh not from Oakland. departing from San Francisco
it's about the same actually American has an eleven
forty one flight from San Francisco that arrives Chicago
five fifty four (and
24 BC that's ) and hour and a half. so that's that's a a
wash
25 TA yeah or wait just one moment. or United has a
twelve oh one a.m. departure that arrives at Chicago
five fifty two a.m.
26 BC oh that sounds good
Sidner: application to
travel agency dialogue
• Sidner points out that
– there are a number of alternative
proposals on offer throughout this
section
– there is more going on than just
questions and answers
• “Hi, my name is BC” is analysed as
a proposal
– Why is this counterintuitive?
Counterproposals in the
AMEX dialogue
• Example repeated:
19 TA there is one on United that leaves Oakland at eleven
thirty p.m. and arrives Chicago five twenty five a.m.
23 TA uh not from Oakland. departing from San Francisco it's
about the same actually American has an eleven forty one
flight from San Francisco that arrives Chicago five fifty four
(and
25 TA yeah or wait just one moment. or United has a twelve
oh one a.m. departure that arrives at Chicago five fifty two
a.m.
• Analysis:
– 19 is analysed as ProposeForAccept
– 23 and 25 analysed as Counter
• Why are they not all analysed as proposals?
over to Stina...
Discussion
Levels in communication
• Allwood, Clark: levels of understanding and
acceptance
–
–
–
–
1. A attends to B’s utterance
2. A perceives B’s utterance
3. A understands B’s utterance (grounding)
4. A accepts or rejects (the content of) B’s utterance
(uptake)
• In GoDiS
– grounding results in modifying SHARED.LU
– uptake results in modifying SHARED.QUD and
SHARED.BEL
GoDiS uses an optimistic
approach to utterance uptake
• 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 addressee 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
the Information State
approach again
• Reformulating postconditions as IS
update rules
– requires specifying preconditions and
effects of moves/messages
– requires specifying exactly when each
update is performed
• This leads to a new view of
Sidner’s account
Mixing of optimistic and
pessimistic strategies
• We saw that Sidner’s account is asymmetric
regarding when different messages are
assumed to be taken up
– ProposeForAccept requires acknowledgement before
OpenStack is affected (“pessimism”)
– But Reject, RP, AP need not be acknowledged before
affecting OpenStack (“optimism”)
• Or, to put it differently
– Sidner assumes pessimistic approach to grounding
and uptake of ProposeForAccept
– but optimistic approach for Reject, Accept,
RetractProposal
Uptake as negotiation
• the account of proposals etc. amounts to, in
part, an account of utterance uptake, which all
utterances are subject to
– questions are seen as proposals
– “My name is B C” is seen as a proposal
• It follows that Sidner views all dialogue as
negotiation
• This is negotiation only in the sense that the
uptake of any utterance can be negotiated
A different type of
negotiation
• But this is a different kind of negotiation
from what’s going on in the AMEX
dialogue when different flights are
proposed and compared
• We make a distinction between
– negotiation of uptake, and
– negotiation of alternatives
Negotiation of alternatives
• What distinguishes negotiative dialogue (in
our sense) from other kinds of dialogue?
• 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
What are proposals?
• questions, assertions and answers are
not normally proposals
• proposals are dialogue moves on the
same level as questions, assertions,
instructions etc.
• as with all other moves, DPs can have
an optimistic (or pessimistic) approach
to grounding and uptake of proposalmoves
Why does Sidner analyse
successive proposals as
counterpropsals?
• If they weren’t, there would be
nothing indicating that they are
related to each other (and 19)
– “Wear something warm” is not a
counterproposal to “Take the 11:30
American flight”
– but “Take the 11:42 United flight” is;
these to proposals are related
A problem with
counterproposals
• related proposals are analysed as
counterproposals, i.e. as conflicting with
previous proposals
– but often alternative proposals do not
conflict with previous proposals (e.g. buying
a CD)
– e.g. a travel agent is usually quite
indifferent to which proposal is accepted
– there’s a difference between “laying out
options” and actually arguing for one of the
options
Negotiable and nonnegotiable issues
• Why does it seem strange to view e.g.
“My name is B C” as negotiation in our
sense?
• Some issues are negotiable, and some
are not!
– depends on activity
– issues may become negotiable, e.g. if a
previous proposal is challenged (“No it’s
not, I’ve met you before and your name is A
D!”)
Conclusion
• We have analysed Sidner’s account of
negotiative dialogue using the
information state approach
• We need to
– make a distinction between negotiation of
uptake, and negotiation of alternatives
– provide a way of explaining how proposals
can be related without being in conflict
– make a distinction between negotiable and
non-negotiable issues
Current work: an alternative
account of negotiation
• Negotiation
– the process of providing a solution (an
answer) to an
– Issue Under Negotiation (IUN), represented
as a question
• Proposals
– add answers to a set of possible answers
related to an IUN
• Uptake
– is handled separately from negotiation, but
– when uptake fails, negotiation may be
needed
counterproposals
• Counter (CO a p b q):
– without rejecting p, a offers q to b
• analysed as two proposals
– (PFA a b p)
– (PFA a(Supports q (Not p))
• A counterproposal requires that the new
proposal conflicts with a previous proposal
• In this way, Sidner can distinguish unrelated
proposals from related proposals
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)
Example
• IUN is ?lx.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(?lx.sel_flight(x)) }
findout((?lx. ccn(x))
book_ticket
BEL = {flight(f1),
dep_time(f1,0745), ... }
TMP = (same structure as SHARED)
IUN =
< ?lx.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