argumentation in agent systems part 2 dialogue
Download
Skip this Video
Download Presentation
Argumentation in Agent Systems Part 2: Dialogue

Loading in 2 Seconds...

play fullscreen
1 / 63

Argumentation in Agent Systems Part 2: Dialogue - PowerPoint PPT Presentation


  • 99 Views
  • Uploaded on

Argumentation in Agent Systems Part 2: Dialogue . Henry Prakken EASSS-07 31-08-2007. Why study argumentation in agent technology?. For internal reasoning of single agents Reasoning about beliefs, goals, intentions etc often is defeasible For interaction between multiple agents

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Argumentation in Agent Systems Part 2: Dialogue ' - anana


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
argumentation in agent systems part 2 dialogue

Argumentation in Agent SystemsPart 2:Dialogue

Henry Prakken

EASSS-07

31-08-2007

why study argumentation in agent technology
Why study argumentation in agent technology?
  • For internal reasoning of single agents
    • Reasoning about beliefs, goals, intentions etc often is defeasible
  • For interaction between multiple agents
    • Information exchange involves explanation
    • Collaboration and negotiation involve conflict of opinion and persuasion
overview
Overview
  • Recent trends in argumentation logics
    • Argument schemes
    • Epistemic vs. practical reasoning
  • Argumentation in dialogue
    • Dialogue game approach
    • Types of dialogues
      • How they involve argumentation
    • The notion of commitment
  • Some dialogue systems
  • Agent behaviour in dialogues
  • Research issues
argument schemes general form
Argument schemes: general form
  • The same as logical inference rules
  • But also critical questions
    • Pointers to undercutters

Premise 1, … , Premise n

Therefore (presumably), conclusion

statistical syllogism
Statistical syllogism
  • P and if P then usually Q is a reason to believe that Q
      • Birds usually fly
  • Critical question: subproperty defeater?
    • Conflicting generalisation about an exceptional class
      • Penguins don’t fly
normative syllogism
“Normative syllogism”
  • P and if P then as a rule Q is a reason to accept that Q
  • Critical question: are thereexceptions?
    • How does a lawyer argue for exceptions to a rule?
      • Say legislation makes an exception
      • Say it is motivated by the rule’s purpose
      • Find an overruling principle
      • Argue that rule application has bad consequences
witness testimony
Witness testimony
  • Critical questions:
    • Is W sincere? (veracity)
    • Did W really see P? (objectivity)
    • Did P occur? (observational sensitivity)

Witness W says P

Therefore (presumably), P

temporal persistence
Temporal persistence
  • Critical questions:
    • Was P known to be false between T1 and T2?
    • Is the gap between T1 and T2 too long?

P is true at T1 and T2 > T1

Therefore (presumably), P is

Still true at T2

arguments from consequences
Arguments from consequences
  • Critical questions:
    • Does A also have bad consequences?
    • Are there other ways to bring about the good consequences?

Action A brings about good consequences

Therefore (presumably), A should be done

types of dialogues walton krabbe

Dialogue Type

Dialogue Goal

Initial situation

Persuasion

resolution of conflict

conflict of opinion

Negotiation

making a deal

conflict of interest

Deliberation

reaching a decision

need for action

Information seeking

exchange of information

personal ignorance

Inquiry

growth of knowledge

general ignorance

Types of dialogues (Walton & Krabbe)
example
P: I offer you this Peugeot for $10000.

P: why do you reject my offer?

P: why are French cars no good?

P: why are French cars unsafe?

P: Meinwagen is biased since German car magazines usually are biased against French cars

P: why does Meinwagen have a very high reputation?.

P: OK, I accept your offer.

O: I reject your offer

O: since French cars are no good

O: since French cars are unsafe

O: since magazine Meinwagen says so

O: I concede that German car magazines usually are biased against French cars, butMeinwagen is not since it has a very high reputation.

O: OK, I retract that French cars are no good. Still I cannot pay $10.000; I offer $8.000.

Example
example 2
P: I offer you this Peugeot for $10000.

P: why do you reject my offer?

P: why are French cars no good?

P: why are French cars unsafe?

P: Meinwagen is biased since German car magazines usually are biased against French cars

P: why does Meinwagen have a very high reputation?.

P: OK, I accept your offer.

O: I reject your offer

O: since French cars are no good

O: since French cars are unsafe

O: since magazine Meinwagen says so

O: I concede that German car magazines usually are biased against French cars, but Meinwagen is not since it has a very high reputation.

O: OK, I retract that French cars are no good. Still I cannot pay $10.000; I offer $8.000.

Example (2)
example 3
P: I offer you this Peugeot for $10000.

P: why do you reject my offer?

P: why are French cars no good?

P: why are French cars unsafe?

P: Meinwagen is biased since German car magazines usually are biased against French cars

P: why does Meinwagen have a very high reputation?.

P: OK, I accept your offer.

O: I reject your offer

O: since French cars are no good

O: since French cars are unsafe

O: since magazine Meinwagen says so

O: I concede that German car magazines usually are biased against French cars, but Meinwagen is not since it has a very high reputation.

O: OK, I retract that French cars are no good. Still I cannot pay $10.000; I offer $8.000.

Example (3)
dialogue systems according to carlson 1983
Dialogue systems (according to Carlson 1983)
  • Dialogue systems define the conditions under which an utterance is appropriate
  • An utterance is appropriate if it furthers the goal of the dialogue in which it is made
  • Appropriateness defined not at speech act level but at dialogue level
  • Dialogue game approach
dialogue game systems
Dialogue game systems
  • A dialogue purpose
  • Participants (with roles)
  • A communication language Lc
    • With embedded topic language Lt and a logic for Lt
  • A protocol for Lc
  • Effect rules for Lc (“commitment rules”)
  • Termination and outcome rules
some history
Some history
  • In philosophy: formal dialectics
    • (Hamblin 1970, MacKenzie 1979, Walton & Krabbe 1995, …)
    • Deductive setting
  • In AI: procedural defeasibility
    • Loui (1998(1992)), Brewka (1994,2001)
    • Adding counterarguments
  • In AI & Law: dispute resolution
    • (Gordon 1993, Bench-Capon 1998, Lodder 1999, Prakken 2000-2006, …)
    • Adding counterarguments and third parties
  • In MAS: agent interaction
    • Parsons-Sierra-Jennings 1998, Amgoud-Maudet-Parsons 2000, McBurney-Parsons 2002, …
    • Adding agents
persuasion
Persuasion
  • Participants:proponent (P) and opponent (O) of a dialogue topic t
  • Dialogue goal:resolve the conflict of opinion on t.
  • Participants’ goals:
    • P wants O to accept t
    • O wants P to give up t
  • Typical speech acts:
    • Claim p, Concede p, retract p, Why p, p since S, …
information seeking
Information seeking
  • Dialogue goal: information exchange
  • Agent’s goals: learning(?)
  • Typical speech acts:
    • Ask p, Tell p, Notell p, …
negotiation
Negotiation
  • Dialogue goal: agreement on reallocation of scarce resources
  • Participants’ goals: maximise individual gain
  • Typical communication language:
    • Request p, Offer p, Accept p, Reject p, …
deliberation
Deliberation
  • Participants:any
  • Dialogue goal:resolve need for action
  • Participants’ goals:
    • None initially
  • Possible set of speech acts:
    • Propose, ask-justify, prefer, accept, reject, …
dialectical shifts to persuasion
Dialectical shifts to persuasion
  • Information exchange: explaining why something is the case or how I know it
    • Persuasion over fact
  • Negotiation: explaining why offer is good for you or bad for me
    • Persuasion over fact or action
  • Deliberation: explaining why proposal is good or bad for us
    • Persuasion over fact or action
commitment in dialogue
Commitment in dialogue
  • Walton & Krabbe (1995):
    • General case: commitment to action
    • Special cases:
      • Commitment to action in dialogue (dialogical or propositional commitment)
      • Commitment to action outside dialogue (social commitment)
    • Negotiation and deliberation lead to social commitments
    • Persuasion leads to dialogical commitments
quality aspects of dialogue protocols
Quality aspects of dialogue protocols
  • Effectiveness: does the protocol further the dialogue goal?
    • Commitments
    • Agents’ logical and dialogical consistency
    • Efficiency (relevance, termination, ...)
  • Fairness: does the protocol respect the participants’ goals?
    • Flexibility, opportunity, …
  • Public semantics: can protocol compliance be externally observed?
effectiveness vs fairness
Effectiveness vs fairness
  • Relevance and efficiency: moves should be related to the dialogue topic
      • Relevance often enforced in rigid so efficient “unique-move immediate response” protocols
      • But sometimes participants must have freedom to backtrack, to explore alternatives, to postpone responses, …
public semantics commitments in persuasion
Public semantics:Commitments in persuasion
  • A participant’s publicly declared standpoints, so not the same as beliefs!
  • Only commitments and dialogical behaviour should count for move legality:
    • “Claim p is allowed only if you believe p”

vs.

    • “Claim p is allowed only if you are not committed to p and have not challenged p”
assertion acceptance attitudes
Assertion/Acceptance attitudes
  • Relative to speaker’s own knowledge!
    • Confident/Thoughtful agent: can assert/accept P iff he can construct an argument for P
    • Careful/cautious agent: can assert/accept P iff he can construct an argument for P and no stronger counterargument
    • Thoughtful/skeptical agent: can assert/accept P iff he can construct a justified argument for P
  • If part of protocol, then protocol has no public semantics!
two systems for persuasion dialogue
Two systems for persuasion dialogue
  • Parsons, Wooldridge & Amgoud
    • Journal of Logic and Computation 13(2003)
  • Prakken
    • Journal of Logic and Computation 15(2005)
pwa languages logic agents
PWA: languages, logic, agents
  • Lc: Claim p, Why p, Concede p, Claim S, Question p
    • p  Lt, S  Lt
  • Lt: propositional
  • Logic: argumentation logic
    • Arguments: (S, p) such that
      • S  Lt, consistent
      • S propositionally implies p
    • Attack: (S, p) attacks (S’, p’) iff
      • p  S’ and
      • level(S) ≤ level(S’)
    • Semantics: grounded
  • Assumptions on agents:
    • Have a knowledge base KB  Lt
    • Have an assertion and acceptance attitude
pwa protocol
PWA: protocol
  • W claims p;
  • B concedes if allowed, if not claims p if allowed or else challenges p
  • If B claims p, then goto 2 with players’ roles reversed and p in place of p;
  • If B has challenged, then:
    • W claims S, an argument for p;
    • Goto 2 for each s  S in turn.
  • B concedes if allowed, or the dialogue terminates.
  • Outcome: do players agree at termination?
slide30

Example persuasion dialogue

P1: My car is safe. claim

P2: Since it has an airbag. argument

P3: why does that not make my car safe? challenge

P4: Yes, that is what the newspapers say, concession but that does not prove anything, since newspapers are unreliable sources of technological information undercutter

P5: OK, I was wrong that my car is safe. retraction

O1: Why is your car safe? challenge

O2: That is true, concession but your car is still not safe counterclaim

O3: Since the newspapers recently reported on airbags exploding without cause rebuttal

O4: Still your car is not safe, since its maximum speed is very high. alternative rebuttal

pwa example dialogue
PWA: example dialogue

P: careful/cautious

P1: claim safe

P2: claim {airbag, airbag  safe}

P3: claim {airbag  safe}

O: thoughtful/cautious

O1: why safe

O2a: concede airbag

O2b: why airbag  safe

P: careful/cautious

P1: claim safe.

P2: whysafe

P3a: concede newspaper

P3b: why newspaper   safe

O: confident/cautious

O1: claimsafe

O2: claim {newspaper,

newspaper   safe}

O3: claim {newspaper   safe}

pwa characteristics
PWA: characteristics
  • Protocol
    • multi-move
    • (almost) unique-reply
    • Deterministic in Lc
  • Dialogues
    • Short (no stepwise construction of arguments, no alternative replies)
    • Only one side develops arguments
  • Logic
    • used for single agent: check attitudes and construct argument
prakken languages logic agents
Prakken: languages, logic, agents
  • Lc: Any, provided it has a reply structure (attacks + surrenders)
  • Lt: any
  • Logic: argumentation logic
    • Arguments: trees of conclusive and/or defeasible inferences
    • Attack: depends on chosen logic
    • Semantics: grounded
  • Assumptions on agents: none.
prakken example lc with reply structure

Acts

Attacked by

Surrendered by

claim p

why p

concede p

why p

p since S

retract p

concede p

retract p

p since S

p’ since S’

why s (s  S)

concede (p since S)

concede s (s  S)

Prakken: example Lc (with reply structure)
protocol variations
Protocol variations
  • Unique-vs multiple moves per turn
  • Unique vs. multiple replies
  • Immediate response or not
prakken protocols basic rules
Prakken: protocols (basic rules)
  • Each noninitial move replies to some previous move of hearer
  • Replying moves must be defined in Lc as a reply to their target
  • Argue moves must respect underlying argumentation logic
  • Termination: if player to move has no legal moves
  • Outcome: what is dialogical status of initial move at termination?
dialogical status of moves
Dialogical status of moves
  • Each move in a dialogue is in or out:
    • A surrender is out,
    • An attacker is:
      • in iff surrendered, else:
      • in iff all its attacking children are out
slide38

P1+

O1-

P2-

P4+

O2-

O3+

P3+

functions of dialogical status
Functions of dialogical status
  • Can determine winning
    • Plaintiff wins iff at termination the initial claim is in; defendant wins otherwise
  • Can determine turntaking
    • Turn shifts if dialogical status of initial move has changed
      • Immediate response protocols (Loui 1998)
  • Can be used in defining relevance
relevant protocols
Relevant protocols
  • A move must reply to a relevant target
  • A target is relevant if changing its status changes the status of the initial claim
  • Turn shifts if dialogical status of initial move has changed
    • Immediate response protocols
slide41

P1+

O1-

P2-

P4+

O2-

O3+

P3+

slide42

P1+

O1-

P2-

P4+

O2+

O3+

P3-

O4+

slide43

P1+

O1-

P2-

P4+

O2-

O3+

P3+

slide44

P1-

O1+

P2-

P4-

O2-

O3+

O4+

P3+

prakken example dialogue1
Prakken: example dialogue

P1: claim safe

O1: why safe

prakken example dialogue2
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

prakken example dialogue3
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

O2a: concede airbag

prakken example dialogue4
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

O2b: safe since newspaper,

newspaper  safe

O2a: concede airbag

prakken example dialogue5
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

O2b: safe since newspaper,

newspaper  safe

O2a: concede airbag

P3a: concede newspaper

prakken example dialogue6
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

O2b: safe since newspaper,

newspaper  safe

O2a: concede airbag

P3b: so whatsince unreliable,

unreliable  so what

P3a: concede newspaper

prakken example dialogue7
Prakken: example dialogue

P1: claim safe

O1: why safe

P2: safe since airbag,

airbag  safe

O2b: safe since newspaper,

newspaper  safe

O2a: concede airbag

O3: safe since high speed,

high speed  safe

P3b: so whatsince unreliable,

unreliable  so what

P3a: concede newspaper

prakken example dialogue8
Prakken: example dialogue

P1: claim safe

O1: why safe

P4: retract safe

P2: safe since airbag,

airbag  safe

O2b: safe since newspaper,

newspaper  safe

O2a: concede airbag

O3: safe since high speed,

high speed  safe

P3b: so whatsince unreliable,

unreliable  so what

P3a: concede newspaper

argument graph

safe

airbag  safe

airbag

safe

safe

newspaper  safe

high speed  safe

newspaper

high speed

Argument graph

so what

unreliable

unreliable  so what

winning and logic
Winning and logic
  • A protocol should respect the underlying logic
  • We want: main claim is in iff it is implied by the exchanged information
    • (except information that is disputed and not defended)
  • Ensured in relevant protocols (under certain conditions)
prakken s relevant protocols characteristics
Prakken’s relevant protocols: characteristics
  • Protocol
    • Multiple-move
    • Multiple-reply
    • Not deterministic in Lc
    • Immediate-response
  • Dialogues
    • Can be long (stepwise construction of arguments, alternative replies
    • Both sides can develop arguments
  • Logic
    • Used for single agent: construct/attack arguments
    • Used for outcome: players jointly build dialectical graph
filibustering
Filibustering
  • Many two-party protocols allow obstructive behaviour:
    • P: claim p
    • O: why p?
    • P: p since q
    • O: why q?
    • P: q since r
    • O: why r?
    • ...
possible sanctions
Possible sanctions
  • Social sanctions:
    • I don’t talk to you any more
  • Shift of burden of proof by third party
    • ...
    • P: q since r
    • O: why r?
    • referee: O, you must defend not-r!
protocol design vs agent design
Protocol design vs. agent design
  • Can protocol designer rely on agent properties?
    • Rationality
    • Cooperativeness
    • Social behaviour
design of dialogical agents
Design of dialogical agents
  • Assertion and acceptance attitudes (PWA)
  • Model choice of move as planning / practical reasoning
    • Amgoud 2006
  • Apply game theory
    • Roth 2007
  • Much work remains to be done
investigation of protocol properties formal proof of experimentation
Investigation of protocol properties(formal proof of experimentation)
  • Does protocol induce “well-behaved” dialogues? (is it fair and effective?)
  • Do agent attitudes, external goals or social conventions induce “well-behaved” dialogues?
  • If a claim is successfully defended, is it implied by
    • The shared or joint commitments of all participants?
    • The shared or joint beliefs of all participants?
  • Do agent attitudes constrain or even predetermine the outcome?
r esearch issues
Research issues
  • Investigation of protocol properties
  • Combinationsof dialogue types
    • Deliberation!
  • Multi-party dialogues
  • Protocol design vs agent design
  • Embedding in social context
  • A framework for dialogue games
further reading
Further reading
  • Argumentation in logic
    • H. Prakken & G. Vreeswijk, Logics for defeasible argumentation (Handbook of Philosophical Logic, 2nd edition)
  • Argumentation in dialogue
    • H. Prakken, Formal systems for persuasion dialogue. The Knowledge Engineering Review 21:163-188, 2006.
    • I. Rahwan et al., Argumentation-based negotiation, The Knowledge Engineering Review 18:343-375, 2003.
  • For more resources see:http://www.cs.uu.nl/people/henry/easss07.html
ad