4th International Workshop on Law of Electronic AgentsICAIL2005Bologna, Italy, 10 June 2005 Monica Palmirani & Regis RiveretCIRSFID - University of Bologna (Italy)

A Multi-agent System for Managing the Normative Consolidation

C.I.R.S.F.I.DUniversity of BolognaResearch Centre of History of Law, Philosophy and Sociology of Law, Computer Science and Law

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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

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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

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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]

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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

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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

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1. Taxonomy of modifications

NormModifications

Modification of the text

repeal

integration

Modification of the norm

range

Modification of the time

substitution

relocation

meaning change

derogationextension

changes of force

changesof efficacy

interpretation

Normative SystemModifications

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1. Taxonomy of modifications (ii)

Modification of the time

Changes of validity

Changesof efficacy

a) Limitation of validity• invalid norms

b) Extension of validity • prorogue norms• renewal norms

a) Limitation of efficacy• suspend norms

b) Extension of efficacy • postpone efficacy• retroactivity• extra-activity

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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

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Normative chain of the document A

Document

Time line

t0 tnti ti+1 tn+1t1 t2

….A0 A1 A2 Ai Ai+1 An-1 An….

M0 M1 Mn-1…. ….

Set of Modifications

f(Aj-1, Mj-1) = Aj

versioning chain vc(A) = An , n = [0, ∞[normative chain nc(A) = vc(A) + (vc(Mj))

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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

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Legislative system at the time tj

Document A

Time line

t0 tnti ti+1 tn+1t1 t2

….A0 A1 A2 Ai Ai+1 An-1 An….

Document D

….D0 D1 Dz Dz+1 Dn….

Document B

….B0 B1 Bk Bk+1 Bn-1 Bn….

…………………………

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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)

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Normative information system

Legal system

Temporal line

t0 tnti ti+1 tn+1t1 t2

….LS0 LS1 LS2 LSi LSi+1 LSn-1 LSn….

M0 M1 Mi Mn-1…. ….

Set of Modifications

engine

In force efficacy applicable

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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)."

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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

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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

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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

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Modifications

Condition Times

-inforce-efficacy

PassiveTime

-app_date-duration

ActiveTime

SpaceConditions CaseConditions EventConditions

Certain unCertaininstantaneousMod futureMod pastMod

hasCondition

hasTime

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Example of conditioned modification

L. n. 328 del 8/11/2000 (in force since: 28/11/2000)Art. 30Repeals. ....

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.

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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

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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

now

e1 e2

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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

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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

URN

DTD

METADATI

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PART II – Régis Riveret

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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)

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A theory in Defeasible Logic

Facts Inforce(Law n.50/99)

Strict rules Law(x) → StateRule(x)

Defeasible rules Repealed(x) => ¬Inforce(x)

Defeaters Conditioned prorogation(x) ~> Inforce(x)

Ranking StateRule > FederalRule

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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

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A toy theory

R1: enter_inforce(x) : t =>p inforce(x) : t+15R2: repeal(x) : t =>p ¬inforce(x) : t R3: Conditional Prorogation (X): t ~>p inforce(x): tR4: revival(x) : t =>p inforce(x) : t

R4>R2>R1

Enter_inforce(Law50/99) : 0Repeal(Law50/99) : tnRevival(Law50/99) : tzCond. Prorogation (Law50/99) : tn+1

0 tn tz

R3>R2

tn+1

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Document repository A

mod

Document repository B

A normative system

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Agents ?

Active norm + events Proactivity

Passive norm Reactivity

Unpredictable normative environment + adaptation

Autonomy

Complex interactions + Collaboration work Sociability Model the complexity

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Node BNode A

Legal operator

Event agent

Normative agent

Consolidation agentProof agent

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thank you for your attention

Monica Palmirani - palmirani@cirfid.unibo.itRegis Riveret – rrivert@cirfid.unibo.it