A Multi-agent System for Managing the Normative Consolidation

A Multi-agent System for Managing the Normative Consolidation 4th International Workshop on Law of Electronic Agents ICAIL2005 Bologna, Italy, 10 June 2005 Monica Palmirani & Regis Riveret CIRSFID - University of Bologna (Italy) C.I.R.S.F.I.D University of Bologna Research Centre of History of Law, Philosophy and Sociology of Law, Computer Science and Law Objective   To present a model of normative information system based on a multi-agent technology The aim is:    to manage the legislative consolidation process in a proactive way to detect inconsistencies in the modification norms to resolve the modifications linked to uncertain future events  To use a logic framework oriented to the legal reasoning in the semantic web meaning 2 LEA2005 Outline Part I – Palmirani  Introduction of the problem  To present a time model for representing the dynamicity of the normative system (not a legislative system)  To introduce a model for producing in semi-automatic way legislative document updated respect three temporal axes:  law in force, efficacy, applicability Part II - Riveret  To present the logic framework based on the defeasible logic  To present the multi-agent architecture LEA2005 3 Introduction of the problem (i)  Several legal information systems (LIS) are managing the consolidation of legislative documents because there is a crucial request from the eGovernment and eDemocracy research field [eEurope2002, eEurope2005, Better lawmaking EU initiative, White paper on governance, DEXA2004] On the other hand these LIS face the problem mostly oriented to the document not to the normative system dynamicity [MetaLex-NL, LexDania-DK, LexGo-CH, NormeInRete-IT, RIS-AT, ADELE-FR] 4  LEA2005 Introduction of the problem (ii)  Furthermore the conditional provisions and other uncertain modification provisions arise some questions about the fitted model and architecture to adopt in order to cope with the consolidation process Several studies [Boella 03-a, Boella 03-b] suggest that we can model a normative systems using a multi-agent schema enabling interaction among agents whose behavior is autonomous, reactive, and proactive  LEA2005 5 Updating law corpora  For updating law corpora we should fix some criteria: 1. define a taxonomy of modifications 2. apply the modifications in the correct sequence 3. define the behaviors of the normative system in case of modifications  It is fundamental to define a time-model for representing the temporal axes:    in force efficacy applicability 6 LEA2005 1. Taxonomy of modifications Modification of the text repeal substitution integration relocation Norm Modifications Modification of the norm range interpretation meaning change derogation extension changes of force changes of efficacy 7 Modification of the time Normative System Modifications LEA2005 1. Taxonomy of modifications (ii) Modification of the time Changes of validity a) Limitation of validity • invalid norms b) Extension of validity • prorogue norms • renewal norms Changes of efficacy a) Limitation of efficacy • suspend norms b) Extension of efficacy • postpone efficacy • retroactivity • extra-activity LEA2005 8 2. Correct sequence  The correct sequence is determined by:  the sequence of modifications in the time  a set of time-information included in the legislative text  the analysis of the conditional provisions  the analysis of the impacts on the normative system LEA2005 9 Normative chain of the document A Time line t0 Document t1 t2 ti ti+1 tn+1 tn A0 A1 A2 …. Ai Ai+1 …. An-1 An Set of Modifications M0 M1 …. …. Mn-1 f(Aj-1, Mj-1) = Aj versioning chain normative chain LEA2005 vc(A) =  An , n = [0, ∞[ nc(A) = vc(A) +  (vc(Mj)) 10 Legislative system: a definition   LS(t) = {a system of norms N that satisfy at least one membership criterion at a given time t} Legislative system is the synchronic view of the norms [Guastini 1998] LS(t) = {D1(t) , D2(t), D3(t), ... Dm(t)} m  N, Dm=document t is a fixed time in a discrete representation LEA2005 11 Legislative system at the time tj Time line t0 Document A t1 t2 ti ti+1 tn+1 tn A0 A1 A2 …. Ai Ai+1 …. An-1 An Document B B0 B1 …. Bk …. Bk+1 Bn-1 Bn ………………………… Document D D0 D1 …. Dz Dz+1 …. Dn LEA2005 12 Normative system: a definition  Normative system is a sequence of legislative system in the time [Guastini 1998, Alchourrón 1971] NS = {LS(t1) , LS(t2), LS(t3), ... LS(tj)} j  N  The normative information system is an IS that include:  all the original legislative texts  all the modifications and the versioning chain  or better all the normative chain of all the texts  Normative information system =  nc(Dj) LEA2005 13 Normative information system Temporal line t0 t1 t2 ti ti+1 tn+1 tn Legal system LS0 LS1 LS2 …. engine LSi LSi+1 …. LSn-1 LSn Set of Modifications M0 M1 …. Mi …. Mn-1 In force LEA2005 efficacy applicable 14 Times in the normative provision    part of text with a normative meaning is a normative provision It is possible to consider a normative provision also as a logic proposition (true or false) composed by two parts: cause and effect  Cause  Effect  Facts  Consequences if the conditions are verified then some effects are expected "Murder is punished." A true proposition: "If F (you kill), then E (you will be punished)." LEA2005 15 Anatomy of a normative provision    So we have three times:  we have the time when the enunciates are included in the “corpora” – date of force  we have the time when the disposition is active for the fact-type – date of efficacy  we have the time when the disposition produce results – date of application usually date of force =date of efficacy= date of application but not always  e.g. retroactive norms LEA2005 16 Toy Example  “for all the students that in the year 2003-2004 had a rate >28/30, the University of Bologna will give a special grant for the year 2004-2005” Time of force June 2005 Time of efficacy 2003-2004 Time of applicability 2004-2005    LEA2005 17 When a disposition is a modification  The period of application of the modification can be:    instantaneously postponed – in the future anticipated – retroactivation effect or  conditioned to an event  certain  uncertain LEA2005 18 Modifications hasTime Condition hasCondition Times PassiveTime SpaceConditions CaseConditions EventConditions -inforce -efficacy ActiveTime -app_date -duration Certain unCertain instantaneousMod futureMod pastMod LEA2005 19 Example of conditioned modification L. n. 328 del 8/11/2000 (in force since: 28/11/2000) Art. 30 Repeals.  .... 2. Since the enter in force of the legislative decree declared in the art. 10, all the provisions about IPAB in the law 17 July 1890, n. 6972 are repealed. Since the enter in force of the legislative decree declared in the article 24, the provisions about the economic incomes in the Law 10 February 1962, n. 66, Law 26 May 1970, n. 381, Law 27 May 1970, n. 382, Law 30 March 1971, n. 118, Law e 11 February 1980, n. 18 and following modifications are repealed. LEA2005 20 3. Some crucial modification types  The normative information system should manage:   Conditioned modifications and the related events The abrogation of abrogation Retroactive abrogation Annulment of a modification by the Constitutional Court decision “Authentic interpretation” that is retroactive for all the normative system Decree not converted in law Substitution of textual parts concerning time definition Modification of modification Modifications that have cycle effect on the normative system        LEA2005 21 Forking model   Manage ex-tunc modifications Fork the versioning lines:  One time-line to register what happen after the court decision with effect ex-tunc (retroactive) in the past  On time-line to register what was happened during a period in the alternative-normative system e1 e2 now LEA2005 22 Current applications  Build in semi-automatic way the law in force  NORMA-SYSTEM project: client/server architecture   Norma-Editor: mark-up in XML in semi-automatic way the text Norma-Server: manage all the versioning system  Application in the Italian Court of Cassation: 200.000 legislative texts  IR respect three different axes:  Law in force  Efficacy  Applicability LEA2005 23 Future applications     Formalise the conditional provisions and modifications in OWL Define a Logic framework based on defeasible logic Define a level of proof Implement a Multi-agent system able to verify the conditions and to make proof METADATI DTD URN LEA2005 24 PART II – Régis Riveret LEA2005 25 Logic Framework for consolidation   Non-monotonic reasoning Choice of Defeasible Logic      suitable for legal reasoning manage incomplete and uncertain facts linear computability suitable with the logic layer of the semantic web Inference engines (DR-Device) 26 LEA2005 A theory in Defeasible Logic  Facts  Inforce(Law n.50/99) Law(x) → StateRule(x) Repealed(x) => ¬Inforce(x) Conditioned prorogation(x) ~> Inforce(x)  Strict rules   Defeasible rules   Defeaters   Ranking  StateRule > FederalRule LEA2005 27 Time integration by two means  Literals labelled by time instants  Inforce(x) :t  Persistent and transient rules Condition :t =>p effect :t  Condition :t =>trans effect :t  LEA2005 28 A toy theory R1: enter_inforce(x) : t =>p inforce(x) : t+15 R2: repeal(x) : t =>p ¬inforce(x) : t R3: Conditional Prorogation (X): t ~>p inforce(x): t R4: revival(x) : t =>p inforce(x) : t R4>R2>R1 R3>R2 Enter_inforce(Law50/99) : 0 Repeal(Law50/99) : tn Revival(Law50/99) : tz Cond. Prorogation (Law50/99) : tn+1 LEA2005 0 tn tn+1 tz 29 A normative system mod Document repository A LEA2005 Document repository B 30 Agents ?    Active norm + events  Proactivity Reactivity Passive norm  Unpredictable normative environment + adaptation  Autonomy Sociability Model the complexity 31  Complex interactions + Collaboration work   LEA2005 Legal operator Proof agent Consolidation agent Normative agent Event agent Node A LEA2005 Node B 32 thank you for your attention Monica Palmirani - palmirani@cirfid.unibo.it Regis Riveret – rrivert@cirfid.unibo.it LEA2005 33