commonsense reasoning and argumentation 14/15 hc 14: dialogue systems for argumentation (2) henry...
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Commonsense Reasoning and Argumentation 14/15
HC 14:Dialogue systems for argumentation (2)
Henry Prakken30 March 2015
Contents Dialogue systems for
argumentation (2) Prakken’s dialogue system framework
Two systems for persuasion dialogue
Parsons, Wooldridge & Amgoud Journal of Logic and Computation
13(2003) Prakken
Journal of Logic and Computation 15(2005)
Prakken: languages, logic, agents
Lc: Any, provided it has a reply structure (attacks + surrenders)
Lt: any Logic: argumentation logic
ASPIC with grounded semantics Assumptions on agents: none.
Prakken: example Lc (with reply structure)
Acts Attacked by
Surrendered by
claim p why p concede p
why p Argue A(Conc(A) = p)
retract p
concede p
retract p
Argue A Argue B(defeats its target)
Why p (p Prem(A))
concede Aconcede p (p Prem(A) or p = Conc(A))
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
Termination: if player to move has no legal moves
… Outcome: what is dialogical status of
initial move at termination?
Dialogical status of moves
Each move in a dialogue is in or out: A surrender is out, An attacker is:
in if surrendered, else: in iff all its attackers are out out iff it has an attacker that is in
(An Argue A move is surrendered iff A’s conclusion is conceded)
Functions of dialogical status
Can determine winning Proponent wins iff at termination the initial claim is
in; opponent wins otherwise Can determine turntaking
Turn shifts if dialogical status of initial move has changed
Immediate response protocols Can be used in defining relevance
1: claim (owe $500)
1: claim (owe $500)
2: why (owe $500)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
12: why (notary’s seal is forged)
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
12: why (notary’s seal is forged)
13: concede (owe $500))
Owe 500
contract no payment
notary’s docsigned by us Not notary’s doc
seal forged
Prakken: example dialogue
P1: claim safe
Prakken: example dialogue
P1: claim safe
O1: why safe
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag O2b: safe since newspaper, newspaper safe
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag O2b: safe since newspaper, newspaper safe
P3a: concede newspaper
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag O2b: safe since newspaper, newspaper safe
P3a: concede newspaper P3b: so what since unreliable, unreliable so what
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag O2b: safe since newspaper, newspaper safe
O3: safe since high speed, high speed safe
P3a: concede newspaper P3b: so what since unreliable, unreliable so what
Prakken: example dialogue
P1: claim safe
O1: why safe
P2: safe since airbag,airbag safe
O2a: concede airbag O2b: safe since newspaper, newspaper safe
O3: safe since high speed, high speed safe
P3a: concede newspaper P3b: so what since unreliable, unreliable so what
P4: retract safe
safeclaim
safeclaim why
safe
airbag airbag safe
claim why
since
safe
airbag airbag safe
claim why
since
concede
safe
airbag airbag safe
safe
newspaper newspaper safe
claim why
since
concede
since
safe
airbag airbag safe
safe
newspaper newspaper safe
claim why
since
concede
since
concede
safe
airbag airbag safe
safe
newspaper newspaper safe
so what
unreliable unreliable so what
claim why
since
concede
since
concede
since
safe
airbag airbag safe
safe
newspaper newspaper safe
safe
high speed high speed safe
so what
unreliable unreliable so what
claim why
since
concede
since
concede
since
since
safe
airbag airbag safe
safe
newspaper newspaper safe
safe
high speed high speed safe
so what
unreliable unreliable so what
retract
claim why
since
concede
since
concede
since
since
Relevant protocols
A reply must be relevant An attacking move is relevant if it changes the status
of the initial move A surrendering move is relevant if an attacking
counterpart is relevant (an attacking counterpart replies to the same (part
of) move) The turn shifts if dialogical status of initial
move has changed Immediate response protocols
P1+
O1-
P2- P4+
O2- O3+
P3+ Relevant target?
P1+
O1-
P2- P4+
O2+ O3+
P3-
O4+
P1+
O1-
P2- P4+
O2- O3+
P3+
Relevant target?
P1-
O1+
P2- P4-
O2- O3+
P3+
O4+
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
12: why (notary’s seal is forged)
What are the relevant targets for ?
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
12: why (notary’s seal is forged)
13: concede (owe $500))
What are the relevant targets for ?
Game for grounded semantics unsound in distributed settings
Paul: p, r
Olga: s, t
p qs qr sr, t p
Knowledge bases Inference rules
P1: q since p
Game for grounded semantics unsound in distributed settings
Paul: p, r
Olga: s, t
Knowledge bases Inference rules
P1: q since p
O1: q since s
p qs qr sr,t p
Game for grounded semantics unsound in distributed settings
Paul: p, r
Olga: s,t, r
Knowledge bases Inference rules
P1: q since p
O1: q since s
P2: s since r
p qs qr sr,t p
Game for grounded semantics unsound in distributed settings
Paul: p, r
Olga: s,t, r
Knowledge bases Inference rules
P1: q since p
O1: q since s
O2: p since r,t
P2: s since r
p qs qr sr,t p
Paul: p, r, p ∧r q,q s
Knowledge bases:
Inference rules:
Rd = {, }Rs = all valid inference rules of prop. l.
Olga: t, t p,p q
No preferences
Find a terminated legal dialogue of five moves with a relevant protocol won by Olga, assuming both are honest
Acts Attacked by
Surrendered by
claim p why p concede p
why p Argue A(Conc(A) = p)
retract p
concede p
retract p
Argue A Argue B(defeats its target)
Why p (p Prem(A))
concede Aconcede p (p Prem(A) or p = Conc(A))
Winning and logic A protocol should respect the underlying logic We want: main claim is in iff it is implied by the
current ‘theory’ of the dialogue (all non-challenged and non-retracted ‘current’ premises)
Ensured in relevant protocols if No surrenders are moved; and Arguments cannot be weakened by ‘backwards
extending’ Each argument implied by the current theory has been
moved Current theory = all non-challenged and non-retractred
current premises
1: claim (owe $500)
2: why (owe $500)
4: argue (owe $500 since contract & no payment)
5: concede (no payment) 6: why (contract)
8: argue (contract since notary’s document & signed by us)
11: argue (notary’s document since notary’s seal is forged)
12: why (notary’s seal is forged)
13: concede (owe $500))
Owe 500
contract no payment
notary’s docsigned by us Not notary’s doc
seal forged
Owe 500
contract no payment
notary’s docsigned by us Not notary’s doc
seal forged
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 in protocol
Commitments Not used (could be used in protocol)
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 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!
Example 2
Paul: pq
Olga: pq p
Knowledge bases Inference rules
P1: claim pModus ponens
…
Paul Olga does not justify p but they will agree on p if players are
conservative, that is, if they stick to their beliefs if possible
Example 2
Paul: pq
Olga: pq p
Knowledge bases Inference rules
P1: claim p
O1: concede p
Modus ponens
…
Paul Olga does not justify p but they will agree on p if players are
conservative, that is, if they stick to their beliefs if possible
Example 2
Paul: pq
Olga: pq p
Knowledge bases Inference rules
P1: claim p
O1: what about q?
Modus ponens
…
Possible solution (for open-minded agents, who are
prepared to critically test their beliefs):
Example 2
Paul: pq
Olga: pq p
Knowledge bases Inference rules
P1: claim p
O1: what about q?
Modus ponens
…
P2: claim q
Possible solution (for open-minded agents, who are
prepared to critically test their beliefs):
Example 2
Paul: pq
Olga: pq p
Knowledge bases Inference rules
P1: claim p
O1: what about q?
Modus ponens
…
P2: claim q
O2: p since q, q p Possible solution (for open-minded agents, who are
prepared to critically test their beliefs):
Problem: how to ensure relevance?