AI Approaches to the Complexity of Legal Systems.- Introduction: Complex Systems and Six Challenges for the Development of Law and the Semantic Web.- I Language and Complex Systems in Law.- As Law Goes By: Topology, Ontology, Evolution.- Sailing the Semantic Seas by Structural Vessels: Problems and Perspectives for the Identification of Implicit Knowledge in the Legal Domain.- Network Analysis of the French Environmental Code.- Model Regularity of Legal Language in Active Modifications.- II Ontologies and the Representation of Legal Knowledge.- Traceability and Change in Legal Requirements Engineering.- When a FrameNet-Style Knowledge Description Meets an Ontological Characterization of Fundamental Legal Concepts.- Application of an Ontology-Based Model to a Selected Fraudulent Disbursement Economic Crime.- Multi-layer Markup and Ontological Structures in Akoma Ntoso.- III Argumentation and Logics.- Prescriptive and Descriptive Obligations in Dynamic Epistemic Deontic Logic.- Lex Minus Dixit Quam Voluit, Lex Magis Dixit Quam Voluit: A Formal Study on Legal Compliance and Interpretation.- IV Dialogue and Legal Multimedia.- Legal Electronic Institutions and ONTOMEDIA: Dialogue, Inventio, and Relational Justice Scenarios.- Mediation, ODR, and the Web 2.0: A Case for Relational Justice.- Legal "Neutral Dialogue", Implementing the Work of Bruce Ackerman in the Field of Law.- Legal Multimedia Management through JPEG2000 Framework.