Introduction Norms Heuristics for Normative Conflict Resolution An Argumentation Inspired Heuristic for Resolving Normative Conflict Nir Oren, Michael Luck, Simon Miles, Timothy J. Norman nir.oren, michael.luck, simon.miles@kcl.ac.uk, t.j.norman@abdn.ac.uk King’s College London, University of Aberdeen 12 May 2008 Nir Oren et al. Heuristics for Normative Conflict
Introduction Norms Heuristics for Normative Conflict Resolution Introduction Alice promised Bob that she would go to the theatre with him. Alice promised her sick mother that she would visit her in hospital. Alice must cook dinner for her friends. Alice must write a paper for her boss. Alice can’t go to the hospital and theatre simultaneously, and cooking dinner does not leave enough time to write the paper. What should Alice do? Nir Oren et al. Heuristics for Normative Conflict
Introduction Norms Heuristics for Normative Conflict Resolution Introduction Alice’s promises, as well as what she should, must, or is allowed to do, can be represented as a set of norms imposed on her. In computational settings, particularly within the agent paradigm, norms are useful for many reasons, including: Norms are declarative. Decisions on whether to comply with norms are decentralised. By reasoning about other’s norms, one may make assumptions about their behaviour. These assumptions may lead to computational savings. Weaknesses of the normative approach includes the problem of resolving normative conflict. Nir Oren et al. Heuristics for Normative Conflict
Introduction Norms Heuristics for Normative Conflict Resolution Overview We examine how an agent may reason about, and resolve normative conflict. The result of such reasoning is a set of norms that the agent will attempt to honour, it will drop, or ignore, norms outside this set. We propose some heuristics, based on argumentation theory, allowing an agent to decide which norms it should comply with. Our focus is on the heuristic, rather than having a complex model of norms. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example A Model of Norms O bob ( theatre ) A norm has a type (obligation, permission, prohibition). A norm is imposed on the agent by some social entity. We refer to this as the norm’s social context . Agents handle norms with different social contexts in very different ways. A norm has a normative goal. We consider norms already adopted by the agent, and thus do not specify a “norm target”. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example A Model of Norms We ignore Conditional norms. Discharge of norms. Temporal effects. Distinctions between actions and states. We assume Norms are all or nothing, if an agent decides to ignore a norm once, they will always ignore the norm. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Agents and the Environment Agents have a set of norms, and are aware of the social contexts associated with the norms. They have preferences (i.e. a partial ordering) over the social contexts. Agents operate within an environment containing the various social contexts, and a set of “states of affairs”, representing the agent’s effects on the environment. Certain states of affairs may be mutually exclusive, capturing the notion that certain norms may not be complied with simultaneously. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Formalisation Norm = N c ( g ) where N ∈ { O , P , F } Environment = � S , C � Normative Agent = ( Norms , ≤ ) mutuallyExclusive : S × S Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Normative Conflict Graph By using its norms and the mutuallyExclusive relation, an agent may generate a normative conflict graph (NCG). A NCG captures those norms that the agent is unable to simultaneously satisfy. The edges of the NCG are directed based on the types of norms. The problem the agent faces may now be seen as selecting a subset of nodes (norms) from the NCG that have no edges between them. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example ( a ) O bob ( theatre ) ( b ) O sickMother ( hospital ) ( c ) O friends ( cooking ) ( d ) O boss ( paper ) ( e ) P superior ( delayPaper ) ( theatre , hospital ) ( hospital , theatre ) ( cooking , paper ) ( paper , delay ) ( cooking , theatre ) ( paper , cooking ) ( hospital , paper ) ( theatre , cooking ) ( delay , paper ) ( paper , hospital ) Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example a b e c d Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Pruning Agents may prune edges from the NCG based on social context preferences (more important social contexts take precedence over less important social contexts). Some agents, referred to as extended normative agents, may have a strict partial ordering over norm types. EA = ( Norms , ≤ , ≺ ) These agents prefer to honour one type of norm over another. Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example ( a ) O bob ( theatre ) ( b ) O sickMother ( hospital ) ( c ) O friends ( cooking ) ( d ) O boss ( paper ) ( e ) P superior ( delayPaper ) friends < bob bob < boss sickMother < boss friends < boss ( theatre , hospital ) ( hospital , theatre ) ( cooking , paper ) ( paper , delay ) ( cooking , theatre ) ( paper , cooking ) ( hospital , paper ) ( theatre , cooking ) ( delay , paper ) ( paper , hospital ) O ≺ P Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example a b e c d Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example a b e c d Nir Oren et al. Heuristics for Normative Conflict
Introduction The Model Norms Normative Conflict Graph Heuristics for Normative Conflict Resolution Example Example a b e c d Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation The Heuristics Our approach: Construct NCG 1 Prune the NCG 2 If edges remain in the graph, use a heuristic to select 3 norms to honour Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation The Random Drop Heuristic Given a normative conflict graph, select an edge (i.e. a normative conflict) at random. If this edge is labelled ( n , m ) , node m (and all edges containing it) are removed from the graph. This process is repeated until no edges remain in the graph. Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation Example a b c Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation Example b c ( b , a ) Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation Example c ( b , a ) , ( c , b ) Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation Example a b c Nir Oren et al. Heuristics for Normative Conflict
Random Drop Introduction Maximal Conflict-free Set Heuristic Norms Preferred Extension Based Heuristic Heuristics for Normative Conflict Resolution Evaluation Example a c ( c , b ) Nir Oren et al. Heuristics for Normative Conflict
Recommend
More recommend
