• [2019-04-20 Sat] Christian’s latest substantive revision of his Non-monotonic Logic (Stanford Encyclopedia of Philosophy) went online today.
• [2019-04-16 Tue] Since last year’s Philosophische Logik - Blog accompanying the course on philosophical logic by Christian was a success, he also decided to accompany this year’s course on Deontic Logic with a blog: Deontic Logic and Normative Reasoning - Blog (this time in English).
• [2019-04-11 Thu] AnneMarie, Dunja and Christian were at Biases in Science - LMU Munich where Dunja gave a talk on Modeling Bias and Deception in Scientific Inquiry on joint work with AnneMarie, Daniel and Christian.
• [2019-03-28 Thu] Ofer’s, AnneMarie’s and Jesse’s paper “Structured Argumentation and Reasoning with Maximal Consistency’’, has been accepted for Annals of Mathematics and Artificial intelligence.
• [2019-03-23 Sat] Game Theory in Practice – Mini-Workshop: AnneMarie Borg (Bochum), Daniel Frey (Heidelberg), Dunja Seselja (Munich), Christian Straßer (Bochum) and Kevin Zollman (Pittsburgh) played a round of Power Grid ;-) (Daniel won.)
• [2019-03-22 Fri] The conference Agent-Based Models in Philosophy – Prospects and Limitations was a great success … thanks to all participants! :-)
• [2019-03-19 Tue] Jesse’s and Ofer’s paper “Simple Contrapositive Assumption-Based Frameworks” has been accepted for LPNMR19.
• [2019-02-15 Fri] Jared’s and Christian’s paper A Logic for Best Explanations has been accepted for the Journal of Applied Non-Classical Logics
• [2019-01-23 Wed] Jesse’s and Christian’s paper A fully rational argumentation system for preordered defeasible rules has been accepted for AAMAS 2019 as a full paper (acceptance rate: 24%).
• [2019-01-23 Wed] Jesse’s and Ofer’s paper Simple Contrapositive Assumption-Based Argumentation Frameworks has been accepted for AAMAS 2019 as an extended abstract.
• more changes

Welcome to the homepage of the Research Group for Non-Monotonic Logic and Formal Argumentation (NMLFA) at the Institute for Philosophy II, Ruhr-University Bochum. The group is funded by a Sofja Kovalevskaja Award of the Alexander von Humboldt-Foundation from September 2014 to September 2019.

The research of the group focuses on formal models of defeasible reasoning with a special focus on argumentation theory, and more broadly non-monotonic logic. We’re specifically interested in logical foundations of formal argumentation, applications of formal argumentation to scientific reasoning, and the method of sequent-based argumentation.

By now the group has published over 40 research papers in top tier journals and top tier conference proceedings in our discipline (e.g., IJCAI, AAMAS, DEON, NMR, KR, AAAI, etc.).

We have organized several conferences and workshops in Bochum.

## The Team

### Members

Currently the group hosts the following researchers:

AnneMarie Borg (PhD-candidate, funded by the Humboldt-foundation, office GA 3/155)
AnneMarie has been working on Justification Logic and Sequent Calculi. Her academic profile can be found here. Her PhD is supervised by Christian and Ofer Arieli. You can write her at annemarie.borg@rub.de

Jesse Heyninck (PostDoc, funded by the Humboldt-foundation, office GA 3/155)
Jesse finished his PhD under the supervision of Ofer Arieli and Christian Straßer in January 2019. He’s especially interested in combinations of defeasible reasoning forms and argument strength (here’s a description of his research project). His homepage can be found here and his CV here. You can write him at jesse.heyninck@rub.de

Pere Pardo Ventura (Post-Doc, funded by the Humboldt-foundation, office GA 3/155)
Pere is working on applications of argumentation and dynamic epistemic logic into defeasible reasoning and deontic logic. A brief CV and list of publications can be found in his homepage https://sites.google.com/site/perepardoventura/home You can write him at pere.pardoventura@mail.ruhr-uni-bochum.de

Christian Straßer (Jun.-Prof., funded by the Humboldt-foundation, office GA 3/39)
Christian is working in non-monotonic logics, defeasible reasoning, argumentation, deontic and adaptive logics, and agent-based models. His CV is here, his list of publications here and his talks ahere. For more information take a look at his academic homepage. His speaking hours are every Wednesday from 10:00–12:00 best write him a mail first. You can write him at christian.strasser@ruhr-uni-bochum.de

### Associate Members

Daniel Frey (Master Student in Economics at University Heidelberg)
Daniel frequently collaborates with us on agent-based models. He is equally interested in the implementation side of things (e.g., NetLogo) and the conceptual considerations underlying formal models.

Sanderson Molick (PhD Student, funded by CARES, office GA 3/39)
He’s doing a PhD under the supervision of Joao Marcos and Christian. His current research is focused on exploring adaptive logics in connection to the anti-exceptionalism debate, with special attention to the problem of logical revision. He can be found on academia.

Dunja Šešelja (Post-Doc, MCMP, LMU Munich)
Dunja is working in the philosophy of science. Her research topics include epistemic and methodological aspects of scientific inquiry, with a special emphasis on the context of scientific diversity. Her recent research mainly focuses on agent-based modeling of scientific inquiry and the question of its epistemic function. You find her CV here, her list of publications here and her list of talks here. Find more information on her academic homepage.

Mathieu Beirlaen (Post-Doc, Humboldt fellow)
Mathieu is working on ampliative reasoning (abduction, inductive generalizations), deontic logic, adaptive logic. Find more information on his homepage, including a list of publications.

### Previous Guests

Lorenz Demey (postdoctoral researcher in philosophical logic at KU Leuven, office GA 3/39)
Lorenz is visiting us from the beginning of July to the end of September 2017. His current research is focused on logical geometry; his other research interests include the philosophies of science, language and mathematics, and the mathematical environment of modal logic (algebra, topology, etc.). His webpages can be found at http://www.lorenzdemey.eu/ and KU Leuven who’s who - Lorenz Demey.

### Collaborators

Ofer Arieli (Professor of Computer Science at the School of Computer Science, The Academic College of Tel-Aviv)
Ofer Arieli co-supervises the PhDs of AnneMarie and Jesse. We often collaborate on Sequent-Based Argumentation (see e.g., Sequent-based logical argumentation - IOS Press). Recently a VIP-visiting grant for 2018 was granted to Ofer by the Research School PLUS (RUB).

Stef Frijters (PhD student, Ghent University)
Stef is a PhD student of Joke Meheus, Frederik Van De Putte and Christian. His special interest is in bringing deontic logic closer to real-life applications such as medical ethics.

Vlasta Sikimic (PhD student, University of Belgrade)
Vlasta co-organized the conference Formal Models of Scientific Inquiry (link) with us. One of her interests concerns the efficiency of knowledge acquisition in laboratory-based research (e.g., in the Fermilab). Besides that she has published on formal logic (e.g., structurality, display calculi) and animal ethics.

## Recent Publications

You find all publications here.

### 2019

• Ofer Arieli, AnneMarie Borg, and Jesse Heyninck,
Structured Argumentation and Reasoning with Maximal Consistency,
Annals of Mathematics and Artificial intelligence, 2019

• Ofer Arieli and Jesse Heyninck,
Simple Contrapositive Assumption-Based Frameworks,
LPNMR, 2019

• Jared Millson and Christian Straßer,
A Logic for Best Explanations,
Journal of Applied Non-Classical Logics, 2019

• Jesse Heyninck and Christian Straßer,
A fully rational argumentation system for preordered defeasible rulesc,
AAMAS 2019 (full paper, acceptance rate: 24%).

Structured argumentation is a family of formal approaches for the handling of defeasible, potentially inconsistent information. Many models for structured argumentation distinguish between strict and defeasible inference rules. Defeasible rules often come with varying degrees of strength which is formally represented by a preorder over the defeasible rules. Various lifting principles have been presented in the literature to determine the relative strength of an argument by considering the strength of the defeasible rules used in its construction. The strength of arguments then comes into play when determining whether an attack (a purely syntactic relationship between arguments) results in a defeat (i.e. a successful attack). In \cite{caminada2007evaluation,Wu-Phd}, several rationality postulates were proposed that serve as a measure to assess the normative rationality of structured argumentation formalisms. In \cite{heyninck2017revisiting}, the first formalism satisfying all rationality postulates for structured argumentation when taking into account totally ordered defeasible rules was proposed. In many settings, assuming a total order greatly limits the realistic modelling capabilities of a formal system, e.g. when agents do not know the actual preferences of each rule or since different agents have different preferences over defeasible rules. Our paper shows that in the more general setting of preorders, violations of several rationality postulates can occur. We show how for a wide class of lifting principles, these violations can be avoided, resulting in the first Dung-based system that satisfies all four rationality postulates for preordered defeasible rule bases.

• Jesse Heyninck,
Investigations into the logical foundations of defeasible reasoning: an Argumentative Perspective,
PhD thesis, Ruhr-University Bochum, 2019 (summa cum laude)

• Jesse Heyninck and Ofer Arieli,
Simple Contrapositive Assumption-Based Argumentation Frameworks,
AAMAS 2019 (extended abstract)

• Ofer Arieli and Christian Straßer,
Logical Argumentation by Dynamic Proof Systems,
Theoretical Computer Science, 2019

In this paper we provide a proof theoretical investigation of logical argumentation, where arguments are represented by sequents, conflicts between arguments are represented by sequent elimination rules, and deductions are made by dynamic proof systems extending standard sequent calculi. The idea is to imitate argumentative movements in which certain claims are introduced or withdrawn in the presence of counter-claims. This is done by a dynamic evaluation of sequences of sequents, in which the latter are considered derived’ or not derived’ according to the content of the sequence. We show that decisive conclusions of such a process correspond to well-accepted consequences of the underlying argumentation framework. The outcome is therefore a general and modular proof-theoretical approach for paraconsistent and non-monotonic reasoning with argumentation systems.

• AnneMarie Borg, Daniel Frey, Dunja Seselja, and Christian Straßer,
Theory-Choice, Transient Diversity and the Efficiency of Scientific Inquiry,
European Journal of Philosophy of Science, 2019

Recent studies of scientific interaction based on agent-based models (ABMs) suggest that a crucial factor conducive to efficient inquiry is what \cite{zollman2010epistemic} has dubbed transient diversity’. It signifies a process in which a community engages in parallel exploration of rivaling theories lasting sufficiently long for the community to identify the best theory and to converge on it. But what exactly generates transient diversity? And is transient diversity a decisive factor when it comes to the efficiency of inquiry? In this paper we examine the impact of different conditions on the efficiency of inquiry, as well as the relation between diversity and efficiency. This includes certain diversity-generating mechanisms previously proposed in the literature (such as different social networks and cautious decision-making), as well as some factors that have so far been neglected (such as evaluations underlying theory-choice performed by scientists).

This study is obtained via an argumentation-based ABM (\cite{ArgABM-HSR,ABM-Lori}). Our results suggest that cautious decision-making does not always have a significant impact on the efficiency of inquiry while different evaluations underlying theory-choice and different social networks do. Moreover, we find a correlation between diversity and a successful performance of agents only under specific conditions, which indicates that transient diversity is sometimes not the primary factor responsible for efficiency. Altogether, when comparing our results to those obtained by structurally different ABMs based on Zollman’s work, the impact of specific factors on efficiency of inquiry, as well as the role of transient diversity in achieving efficiency, appear to be highly dependent on the underlying model.

• H. van Ditmarsch, M. Gattinger, L. B. Kuijer and P. Pardo,
Strengthening Gossip Protocols using Protocol-Dependent Knowledge,
Journal of Applied Logics - IFCoLog Journal of Logics and their Applications 6(1), 2019

• AnneMarie Borg, Ofer Arieli and Christian Straßer,
Reasoning with maximal consistency by argumentative approaches,
Journal of Logic and Computation, forthcoming.

### 2018

• Jesse Heyninck,
Relations between Assumption-Based approaches in nonmonotonic logic and formal argumentation: from Structured Argumentation to Adaptive Logics
accepted for the Journal of Applied Logic special issue for IsraLog’2017

• Mathieu Beirlaen, Jesse Heyninck, and Christian Straßer,
A critical assessment of Pollock’s work on logic-based argumentation with suppositions,
NMR 2018.

• H. van Ditmarsch, J. van Eijck, P. Pardo, R. Ramezanian and F. Schwarzentruber
Dynamic Gossip,
Bulletin of the Iranian Mathematical Society, Springer

• Mathieu Beirlaen, Jesse Heyninck, Pere Pardo, Christian Straßer,
Argument Strength in Formal Argumentation,
IFCOLOG, 5(1), pp. 629–676

• Mathieu Beirlaen, Jesse Heyninck, and Christian Straßer,
A Critical Assessment of Pollock’s Accounts of Suppositional Argumentation,

COMMA 2018

• AnneMarie Borg,
Equipping sequent-based argumentation,

COMMA 2018

• AnneMarie Borg and Christian Straßer,
Relevance and Contamination in Structured Argumentation,

IJCAI 2018 (acceptance rate 20%)

• P. Pardo, E. Sarrión-Morillo, F. Soler-Toscano and F. R. Velázquez-Quesada,
Tuning the program transformers from LCC to PDL

Journal of Applied Logics (IfColog Journal of Logics and their Applications) 5(1) pp.71-96

• Jesse Heyninck and Christian Straßer,
A Comparative Study of Assumption-Based Approaches to Reasoning with Priorities,

Second Chinese Conference on Logic and Argumentation.

• Jesse Heyninck and Ofer Arieli,
On the Semantics of Simple Contrapositive Assumption-Based Argumentation Frameworks
Second Chinese Conference on Logic and Argumentation.

• AnneMarie Borg, Ofer Arieli and Christian Straßer,
Hypersequent-based Argumentation: An Instantiation in the Relevance Logic RM.
In: Theory and Applications of Formal Argumentation 2017. Lecture Notes in Computer Science, vol 10757. Springer.

• AnneMarie Borg, Ofer Arieli,
Hypersequential Argumentation Frameworks: An Instantiation in the Modal Logic S5,
AAMAS 2018 (acceptance rate 25%).

• Ofer Arieli, AnneMarie Borg, Christian Straßer,
Prioritized Sequent-Based Argumentation
AAMAS 2018 (acceptance rate 25%).

• Daniel Frey and Dunja Šešelja,
Robustness and Idealizations in Agent-Based Models of Scientific Interaction,
British Journal for the Philosophy of Science.

• Daniel Frey and Dunja Šešelja,
What is the Epistemic Function of Highly Idealized Agent-Based Models of Scientific Inquiry?,
Philosophy of the Social Sciences.

## Recent and Upcoming Talks

You find all talks here.

### 2019

• Dunja Šešelja,
Understanding scientific inquiry via agent-based modeling,
6th International Congress of Logic, Methodology and Philosophy of Science and Technology (CLMPST 2019), held in Prague, 5-10 August 2019, invited talk for the section on Empirical and Experimental Philosophy of Science. (invited talk)

• AnneMarie Borg, Daniel Frey, Dunja Šešelja, and Christian Straßer, Modeling Bias and Deception in Scientific Inquiry at Biases in Science - LMU Munich.

• Jesse Heyninck,
Investigations into the Logical Foundations of Defeasible Reasoning: an Argumentative Perspective,
a tutorial at “A Primer on Formal Argumentation” which is a lecture series for PhD students in the Doctoral School in Philosophy and Human Sciences, University of Milan (in January 2019).

### 2018

• Dunja Šešelja,
Using Agent-Based Models to Explain Scientific Inquiry: current limitations and future prospects (based on joint work with Daniel Frey)
at Interdisciplinary Center for Science and Technology Research, University of Wuppertal, November 7, 2018 (invited talk)
• AnneMarie Borg, Daniel Frey, Dunja Šešelja, and Christian Straßer,
Agent-Based Models of Scientific Inquiry: Towards Robust Findings,
Multiple Models Workshop, University of Helsinki, 2-3 October 2018,
• AnneMarie Borg and Christian Straßer,
Relevance and Contamination in Structured Argumentation,
at IJCAI 2018 in Stockholm, Sweden, 16-19th July
• Ofer Arieli, AnneMarie and Christian Straßer,
Prioritized Sequent-Based Argumentation,
at AAMAS 2018 in Stockholm, Sweden, 11-13th July
• Ofer Arieli and AnneMarie Borg,
Hypersequential Argumentation Frameworks: An Instantiation in the Modal Logic S5,
at AAMAS 2018 in Stockholm, Sweden. 11-13th July
• Daniel Frey and Dunja Šešelja,
Why Did It Happen the Way It Did? Using Agent-Based Models to Explain Past Scientific Episodes,
at Computational Modeling in Philosophy, LMU Munich, 22-23 June 2018
• Dunja Šešelja,
Mechanisms of Transient Diversity in Agent-Based Models of Scientific Inquiry,
at MCMP, LMU Munich June 27, 2018 (presenting joint work with AnneMarie Borg, Daniel Frey and Christian Straßer)
• Jesse Heyninck and Christian Straßer,
A Comparative Study of Assumption-Based Approaches to Reasoning with Priorities,
Second Chinese Conference on Logic and Argumentation, 2018
• Ofer Arieli and Jesse Heyninck
, On the Semantics of Simple Contrapositive Assumption-Based Argumentation Frameworks,
Second Chinese Conference on Logic and Argumentation, 2018
• Ofer Arieli and AnneMarie Borg
, Hypersequential Argumentation Frameworks: An Instantiation in the Modal Logic S5,
UniLog 2018 in Vichy, France, 21-26th June
• Jesse Heyninck and Christian Straßer
, Unrestricted Rebut in Structured Argumentation,
2nd Workshop on Argument Strength, Toulouse, France, 2018
• Mathieu Beirlaen, Jesse Heyninck and Christian Straßer,
Contrapostion in Structured Argumentation,
2nd Workshop on Argument Strength, Toulouse, France, 2018

## Conferences and Workshops

### Forthcoming

• Agent-Based Models in Philosophy – Prospects and Limitations (2019)
Organized by: Gergor Betz (KIT, Karlsruhe), Dunja Seselja (LMU, Munich), and Christian Straßer (RUB, Bochum)
Keynotes: Corinna Elsenbroich (Surrey), Rainer Hegselmann (Bayreuth), Cailin O’Conner (Irvine), Samuli Reijula (Tampere), Daniel Singer (University of Pennsylvania), Kevin Zollman (Carnegie Mellon)

### Past

1. Bridging the Gap between Formal Argumentation and Actual Human Reasoning (2018)
Organized by: Ofer Arieli (Tel Aviv), AnneMarie Borg (RUB), Marcos Cramer (Dresden), Jesse Heyninck (RUB), Pere Pardo Ventura (RUB), Christian Straßer (RUB)
Keynotes: Ofer Arieli (Tel Aviv), Federico Cerutti (Cardiff), Antonis Kakas (Cyprus), Chris Reed (Dundee), Alice Toniolo (St.-Andrews), Serene Villata (INRIA, Sophia Antipolis), Adam Wyner (Swansea)
2. Formal Models of Scientific Inquiry (2017)
Organized by: AnneMarie Borg (RUB), Dunja Seselja (RUB), Vlasta Sikimic (Belgrade), and Christian Straßer (RUB),
Keynotes: Gregor Betz (KIT, Karlsruhe), Leah Henderson (Groningen), Jason McKenzie Alexander (LSE, London)
3. Argument Strength (2016)
Organized by: Mathieu Beirlaen (RUB), AnneMarie Borg (RUB), Jesse Heyninck (RUB), Pere Pardo (RUB), Dunja Seselja (RUB), and Christian Straßer (RUB),
Keynotes: Gerhard Brewka (Leipzig), Dov Gabbay (London), Gabriele Kern-Isberner (Dortmund), Beishui Liao (Zhejiang), Henry Prakken (Utrecht), Leon Van Der Torre (Luxembourg)
4. Logic in Bochum (2016)
Organized by: AnneMarie Borg (RUB), Mathieu Beirlaen (RUB), Jesse Heyninck (RUB), Pere Pardo (RUB), Dunja Seselja (RUB), and Christian Straßer (RUB),
Keynotes: Joao Marcos (Natal), Gabriella Pigozzi (Paris), Niko Strobach (Münser), Allard Tamminga (Utrecht/Groningen)

## Teaching

You find a complete overview of the teaching activities of the group here.

### Forthcoming

• Christian Straßer,
On Gentle Murderers and Drowning Twins: Deontic Logic and Normative Reasoning
Master and Bachelor Course at RUB

Deontic logics offer a formal explication of reasoning with normative notions such as obligations and permissions. It forms a subclass of modal logic. Its applications are far-reaching, from ethics to computer science and artificial intelligence to legal reasoning.

In this course we start off with standard deontic logic. This system has the virtue of simplicity but it has severe limitations. One such limitation concerns the handling of normative conflicts (for instance, when you make two promises that you cannot both fulfill), another one concerns conditional norms (for instance, think of a sign which says “Parents are allowed only if accompanied by children”). Therefore, we will study several central alternative systems that were devised to tackle these and other problems, such as input/output logic, defeasible deontic logic, deontic default logic, deontic STIT-logic, formal argumentation, etc.

For the seminar previous knowledge of modal logic does not hurt but is in no way required. Nevertheless, a basic understanding of classical propositional logic is advised. Exercises will be discussed in the beginning of every session.

The content of the course has quite some cross-fertilizing potential since many formal methods to be discussed can also be found in other applications of logic. For instance: (i) Participants have the opportunity to familiarize themselves with central methods in modal logic which form the basis of many other philosophically relevant formalisms such as epistemic and temporal logic. (ii) Many systems of deontic logic handle conflicting information and give rise to non-monotonic behavior. In this sense deontic logics offer a showcase of methods that play an essential role in (non-deductive) defeasible reasoning.

• Dunja Seselja,
Contemporary Discussions in Epistemology
Master Course at LMU

### Winter Term 2018/2019

• Pere Pardo,
Epistemic Logic,
Master of Cognitive Science (RUB)
• Christian Straßer,
Übung: Philosophische Logik,
Bachelor Course at RUB
• Jesse Heyninck,
Investigations into the Logical Foundations of Defeasible Reasoning: an Argumentative Perspective,
tutorial at A Primer on Formal Argumentation, a lecture series for PhD students in the Doctoral School in Philosophy and Human Sciences, University of Milan (in January 2019)

### Summer Term 2018

• Dunja Seselja,
Computer simulations in social epistemology of science (expert tutorial)
at the Intensive Course for Philosophy Graduate Students: Computer Simulations and Numerical Experiments in Philosophy of Science, University of Belgrade, Serbia. (May 7-12, 2018)
• Christian Straßer,
Formal Argumentation (short tutorial)
at the Intensive Course for Philosophy Graduate Students: Computer Simulations and Numerical Experiments in Philosophy of Science, University of Belgrade, Serbia. (May 7-12, 2018)
• Christian Straßer,
Prädikatenlogik: Logik II
Bachelor at RUB
• Christian Straßer,
Übung: Prädikatenlogik: Logik II
Bachelor at RUB
• Christian Straßer and Heinrich Wansing,
Colloquium for Logic and Epistemology
Master and PostGrad at RUB
• Pere Pardo,
Introductory Course on Logic,
Cognitive Science Master at RUB
• Dunja Seselja,
Models and Simulations of Scientific Inquiry,
Bachelor and Master at RUB
• Dunja Seselja,
Integrated History and Philosophy of Science,
Bachelor and Master at RUB

### Winter Term 2017/2018

• Dunja Seselja,
Introduction to Scientific Rationality,
Bachelor at University of Vienna
• Dunja Seselja,
Contemporary Discussions on Scientific Pluralism,
Master at University of Vienna
• Dunja Seselja,
Argumentation in Context,
RUB, Optionalbereich
• Dunja Seselja,
Debating,
RUB, Optionalbereich
• Jesse Heyninck,
Logic Boot Camp 2018,
a two day intensive course for bachelor and master students (organised together with Daniel Skurt), Ruhr-University, Bochum.
• Christian Straßer,
Grundkurs Logik: Einführungsvorlesung in die Logik,
Lecture at RUB
• Christian Straßer,
Übung zum Grundkurs Logik,
Exercise at RUB
• Christian Straßer and Heinrich Wansing,
Colloquium for Logic and Epistemology,
Master and PostGrad at RUB
• Pere Pardo,
Epistemic Logic,
Master of Cognitive Science

## Contact

We are situated at

Ruhr-University Bochum
Universitätsstraße 150
44801 Bochum
Building GA
Office 3/39 (Christian and Dunja)
Office 3/155 (AnneMarie, Jesse, Mathieu, and Pere)
Tel.: +49234-3224721 (office 3/39) and +49234-3228714 (office 3/155)
Email: christian dot strasser at rub dot de`

Created: 2019-04-22 Mon 11:26

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