Enforcement in Abstract Argumentation via Boolean Optimization

Computational aspects of argumentation are a central research topic of modern artificial intelligence. A core formal model for argumentation, where the inner structure of arguments is abstracted away, was provided by Dung in the form of abstract argumentation frameworks (AFs). AFs are syntactically directed graphs with the nodes representing arguments and edges representing attacks between them. Given the AF, sets of jointly acceptable arguments or extensions are defined via different semantics. The computational complexity and algorithmic solutions to so-called static problems, such as the enumeration of extensions, is a well-studied topic. Since argumentation is a dynamic process, understanding the dynamic aspects of AFs is also important. However, computational aspects of dynamic problems have not been studied thoroughly. This work concentrates on different forms of enforcement, which is a core dynamic problem in the area of abstract argumentation. In this case, given an AF, one wants to modify it by adding and removing attacks in a way that a given set of arguments becomes an extension (extension enforcement) or that given arguments are credulously or skeptically accepted (status enforcement). In this thesis, the enforcement problem is viewed as a constrained optimization task where the change to the attack structure is minimized. The computational complexity of the extension and status enforcement problems is analyzed, showing that they are in the general case NP-hard optimization problems. Motivated by this, algorithms are presented based on the Boolean optimization paradigm of maximum satisfiability (MaxSAT) for the NP-complete variants, and counterexample-guided abstraction refinement (CEGAR) procedures, where an interplay between MaxSAT and Boolean satisfiability (SAT) solvers is utilized, for problems beyond NP. The algorithms are implemented in the open source software system Pakota, which is empirically evaluated on randomly generated enforcement instances

Strong Refinements for Hard Problems in Argumentation Dynamics

Peer reviewe

Revisiting the "Compliance-vs.-Rebalancing" Debate in WTO Scholarship a Unified Research Agenda

This paper constitutes an attempt to reframe and eventually deflate the ongoing “compliance-vs.-rebalancing” debate which has permeated WTO scholarship for the last 10 years. At face value, this controversy circles around object and purpose of WTO enforcement and the legal nature of dispute panels’ recommendations: Compliance advocates maintain that the objective of WTO enforcement is to induce compliance with DSB panel/AB rulings, and to deter future violations of the Agreement, while rebalancing advocates detect an inherent “pay-or-perform” logic in WTO enforcement. In the paper we examine the shortcomings of each approach separately. Our main criticism, however, concerns the substance of the entire debate. We find that scholars on both sides of the compliance/rebalancing controversy put an unduly rigid emphasis on the subsequent issues of WTO enforcement and the interpretation of the wording of the dispute settlement understanding. They thereby neglected systemic issues of contracting, viz. the nature of contractual entitlements, the need for trade policy flexibility mechanisms and the optimal design of the appropriate remedies. We redefine and recalibrate the compliance/rebalancing controversy along the lines of the nature of the WTO contract. This results in to three key findings: First, none of the two schools of thought succeeds in giving an accurate picture of the WTO treaty. Second, the two perspectives actually portray two strikingly different concepts of the WTO contract, and therefore have been at cross-purposes from the very beginning. This implies a third finding: The two schools of thought essentially describe different facets of the same complex WTO contract. Hence, they have hardly been at loggerheads at all, and are actually complementing each other in important aspects. We lay out a unified research agenda that practitioners, economists, trade lawyers, and international relations scholars alike can accept. The agenda may contribute to reconciling the two opposing views and help WTO scholarship tackle the real systemic issues of the WTO Agreement.WTO, dispute settlement, incomplete contracts, remedies, enforcement

SAT for argumentation

Peer reviewe

SAT-Based Approaches to Adjusting, Repairing, and Computing Largest Extensions of Argumentation Frameworks

Peer reviewe

The Power of Rational Discourse and the Legitimacy of International Governance

governance; legitimacy; participation

The Economic Optimality of Sanction Mechanisms in Interorganizational Ego Networks – A Game Theoretical Analysis –

Even though small- and medium-sized firms (SMEs) were believed not to proceed beyond exporting in their internationalization routes, we can observe new types of co-operation intensive entrepreneurial firms – so-called “micromultinational enterprises” (mMNEs) – entering the global landscape. These firms face the challenge to manage and control a portfolio of national and international alliances simultaneously (ego network). The aim of this paper is to provide game theoretically consolidated conditions in order to analyze the effectiveness and efficiency of interorganizational sanction mechanisms in an alliance portfolio setting. A game theoretical framework is developed over three stages with increasing complexity. Results show that two out of six analyzed sanction mechanisms do not fulfill the game theoretical condition for effectiveness. The efficiency analysis sensibilizes for discretionary elements in governance structures and demonstrates that not one single sanction mechanism but rather the right choice and combination of different types of sanction mechanisms leads to efficient results. We contribute to the international business, alliance, and network literature in several ways by focusing on alliance portfolios held by mMNEs. In doing so, we move beyond the dyadic level and analyze sanction mechanisms from an ego network perspective, a still widely under-emphasized topic in the literature.alliance portfolio, ego network, governance, sanctions, game theory

Thomas S. Schelling: game theory and indirect communication

In their recent work Thomas S. Schelling (2007, 2010), reiterating original arguments about game theory and its applications to social sciences. In particular, game theory helps to explore situations in which agents make decisions interdependent (strategic communication). Schelling's originality is to extend economic theory to social sciences. When a player can anticipate the options and influence the decisions of others. The strategy, indirect communication plays a crucial role. To illustrate, we investigate how to perform the payoff matrix in cases of bribery and threatSocial Science, Schelling, game theory, strategic communications, bribes, threats

Argumentation update in YALLA (Yet Another Logic Language for Argumentation)

International audienceThis article proposes a complete framework for handling the dynamics of an abstract argumentation system. This frame can encompass several belief bases under the form of several argumentation systems, more precisely it is possible to express and study how an agent who has her own argumentation system can interact on a target argumentation system (that may represent a state of knowledge at a given stage of a debate). The two argumentation systems are defined inside a reference argumentation system called the universe which constitutes a kind of “common language”. This paper establishes three main results. First, we show that change in argumentation in such a framework can be seen as a particular case of belief update. Second, we have introduced a new logical language called YALLA in which the structure of an argumentation system can be encoded, enabling to express all the basic notions of argumentation theory (defense, conflict-freeness, extensions) by formulae of YALLA. Third, due to previous works about dynamics in argumentation we have been in position to provide a set of new properties that are specific for argumentation update

Public Debt and the Future of the EU's Stability and Growth Pact

Monetary policy and fiscal policy are connected in various ways. This is why the adoption of the Euro as a common European currency has been accompanied by the setup of the European Union's Stability and Growth Pact, a framework for the coordination of the EU countries' fiscal policies. In this paper, we provide a short overview of the SGP's history of origins and the degree to which the EU Member States adhered to it. Further, we analyse what effects public debt and public deficits have and whether, after all, public debt should be limited in one way or the other. Along these lines, the case for budgetary policy coordination in the special context of the Economic and Monetary Union is presented. After looking at the current SGP framework, we shed light on its main shortcomings and present various reform proposals, all of which are critically questioned. Finally, we present a case for a more flexible country-by-country approach to the interpretation of the deficit criterion (based on some simple algebra). --Stability and Growth Pact (SGP),public debt,public deficits,fiscal policy,policy coordination,Maastricht criteria