Arguing Agents in a Multi- Agent System for Regulated Information Exchange Pieter Dijkstra

Regulated information exchange Information exchange is often regulated by data protection laws Hardcoding these laws in communication protocols: Ensures compliance with the law But in a rigid way, ignoring exceptional circumstances, social goals... Allow for argumentation

ANITA: MAS for exchanging crime-related information Goal of police organisation: exchange as much information as possible But stay within the law Goal of crime investigators: protect their investigation Anonymity of informants! How to balance these goals? Allow agents to argue with each other; But also to reason internally about their goals

Example P: Tell me all you know about recent trading in explosive materials (request) P: why don’t you want to tell me? P: why aren’t you allowed to tell me? P: You may be right in general (concede) but in this case there is an exception since this is a matter of national importance P: since we have heard about a possible terrorist attack P: OK, I agree (offer accepted). O: No I won’t (reject) O: since I am not allowed to tell you O: since sharing such information could endanger an investigation O: Why is this a matter of national importance? O: I concede that there is an exception, so I retract that I am not allowed to tell you. I will tell you on the condition that you don’t exchange the information with other police officers (offer)

Example P: Tell me all you know about recent trading in explosive materials (request) P: why don’t you want to tell me? P: why aren’t you allowed to tell me? P: You may be right in general (concede) but in this case there is an exception since this is a matter of national importance P: since we have heard about a possible terrorist attack P: OK, I agree (offer accepted). O: No I won’t (reject) O: since I am not allowed to tell you O: since sharing such information could endanger an investigation O: Why is this a matter of national importance? O: I concede that there is an exception, so I retract that I am not allowed to tell you. I will tell you on the condition that you don’t exchange the information with other police officers (offer)

Example P: Tell me all you know about recent trading in explosive materials (request) P: why don’t you want to tell me? P: why aren’t you allowed to tell me? P: You may be right in general (concede) but in this case there is an exception since this is a matter of national importance P: since we have heard about a possible terrorist attack P: OK, I agree (offer accepted). O: No I won’t (reject) O: since I am not allowed to tell you O: since sharing such information could endanger an investigation O: Why is this a matter of national importance? O: I concede that there is an exception, so I retract that I am not allowed to tell you. I will tell you on the condition that you don’t exchange the information with other police officers (offer)

The communication language Speech actAttackSurrender request(  )offer (  ’), reject(  ) - offer(  )offer(  ’) (  ≠  ’), reject(  )accept(  ) reject(  )offer(  ’) (  ≠  ’), why-reject (  ) - accept(  ) -- why-reject(  )claim (  ’) - claim(  )why(  )concede(  ) why(  )  since S (an argument)retract(  )  since Swhy(  ) (   S) deny(  ) (   S)  ’ since S’ (a defeater) concede(  ) concede  ’ (  ’  S) concede(  ) -- retract(  ) -- deny(  ) --

The protocol Start with a request Repy to a previous move of the other agent Pick your replies from the table Finish persuasion before resuming negotiation Turntaking: In nego: after each move In pers: various rules possible Termination: In nego: if offer is accepted or someone withdraws In pers: if main claim is retracted or conceded

Example dialogue formalised P: Request to tell O: Reject to tell P: Why reject to tell? Embedded persuasion... O: Offer to tell if no further exchange P: Accept after tell no further exchange

Persuasion part formalised O: Claim Not allowed to tell P: Why not allowed to tell? O: Not allowed to tell since telling endangers investigation & What endangers an investigation is not allowed P: Concede What endangers an investigation is not allowed O: Why National importance? P: National importance since Terrorist threat & Terrorist threat  National importance P: Exception to R1 since National importance & National importance  Exception to R1

Persuasion part formalised O: Claim Not allowed to tell P: Why not allowed to tell? O: Not allowed to tell since telling endangers investigation & What endangers an investigation is not allowed P: Concede What endangers an investigation is not allowed O: Why National importance? P: National importance since Terrorist threat & Terrorist threat  National importance P: Exception to R1 since National importance & National importance  Exception to R1 P: Concede Exception to R1

Persuasion part formalised O: Claim Not allowed to tell P: Why not allowed to tell? O: Not allowed to tell since telling endangers investigation & What endangers an investigation is not allowed P: Concede What endangers an investigation is not allowed O: Why National importance? P: National importance since Terrorist threat & Terrorist threat  National importance P: Exception to R1 since National importance & National importance  Exception to R1 O: Concede Exception to R1 O: Retract Not allowed to tell

Agent Design Knowledge of Regulations Goals Consequences of actions Reasoning Defeasible Dialogue policies Negotiation Persuasion Belief revision policies

Negotiation policy of responding agent Perform requested action? Obliged? yes: accept no: → Forbidden? yes: reject no: → Violation of own interests? no: accept yes: → Try to find conditions yes: counteroffer no: reject

Persuasion policy for responding agent (1) How to respond to “p since Q”? Does the argument satisfy the context criteria? yes: concede premises and conclusion no: → Does KB imply p? yes: concede conclusion no: → Does KB warrant a counterargument (for not-p or an exception)? yes: state counterargument yes or no: → Investigate each premise q in Q

Persuasion policy for responding agent (2) How to respond to premise q of “p since Q”? Is the argument of the form p since p? yes: deny p no: → Does KB imply q? yes: concede q no: → Does KB imply not-q? yes: state argument for not-q no: why q

Persuasion policy for responding agent (3) How to respond to “why p”? Does KB warrant an argument p since Q? yes: state “p since Q” no: retract p

Conclusion We have integrated three strands of theoretical work on dialogue in a MAS application scenario: Argumentation logics Dialogue systems Dialogue strategies for agents