Reprise 2013-2014. Séance du 14 novembre 2013

Le Groupe de Travail reprend ses activités. Pour le premier semestre de l'année 2013-2014, les séances auront lieu le jeudi. Un prochain billet donnera toutes les informations.

Le GdT reprend dès le 14 novembre (la semaine prochaine) avec

Structures and Properties

Matthieu Gallais

Résumé :
In order to define the notion of compatibility between fictional models and target systems, not only the properties, but also the second-order relations between those properties need to be preserved.
According to the structuralist view of models, a target system is compatible with a model if there is an isomorphism mapping between their structures.
But an isomorphism is just a structural identity that ensures that all the properties in a structure have a counterpart in the other structure, not that it is the same property.
Then, in which sense is a property of a model-object linked to a property of real object?

Séance du 20 juin (attention au lieu!)

Modelling of a cognitive agent: processes and logic.

Christel Grimaud

20 juin, 13h-15h
Salle F0.13, Maison de la Recherche (attention, salle différente)

Résumé :
This talk will be two-fold. First I will introduce the problem of providing a logical and neural model for a cognitive agent, and ask what can be reasonable goals, and what requisites this entails on the logic to use. More precisely, I will distinguish between two kinds of reasoning processes, one I call deliberative reasoning, and the other automatic inferences. I will explain why it is reasonable to hope to provide a neural model for automatic inferences, whereas it is not for deliberative reasoning. Thus restricting myself to automatic inferences, I will suggest a plausible neural process for these, and ask what logic could model it. This will bring me to dismiss frst any logical modelling relying on possible worlds, and second, any logical modelling involving defeating
relations.
The second half of the talk will essentially take up again the content of my recently submitted paper. I will present what I think is a suitable logic for automatic inferences, namely the one based on partial worlds models (which I introduced already in my previous talk). Then I will tackle again the problem of providing a complete set of rules for inference relations induced by these models. In my previous talk, I proposed to do this by the means of a compatibility relation. This time I will analyse the question in terms of defnable sets of partial worlds, and propose instead to enrich the language with an additional connective. Within this renewed framework, I will provide two representation theorems: one for inference relations induced by admissible smooth models, and another for relations induced by admissible ranked models.

Séance du 30 mai

Repetition ranks: "why don't you just keep Felscher's rules?"

Nicolas Clerbout

30 mai, 11h-13h (Attention à l'horaire)
Salle D. Corbin

Résumé :
Apart from S. Rahman and his collaborators, most of the people knowing and/or working on dialogues keep Felscher's account in mind. This is mostly because his presentation is technically precise and because he provided one of the first accurate and complete proofs of an equivalence theorem in [3]. Even in the last decade, almost every work about dialogues which was not done by a direct collaborator of S. Rahman was done with Felscher's rules: for example [4, 5, 6, 7]. Thus, it is no suprise that we often face the question  "Why don't you just keep Felscher's rules?", especially in reaction to the device of repetition ranks as I introduced it [1, 2].


The main purpose of this talk is to give an answer to this disguised reproach. To do this I will recall and comment quite extensively Felscher's rules. Although it is an excuse to insist once more on the benefits of repetition ranks, there is another good reason for this flashback. As dialogicians we must be able to discuss with people knowing only Felscher's rules, if only to explain and convince that our account should be preferred. So we must know the answers to questions such as:
- What is the E-rule and what is the big deal with it?
- Does Felscher have something like ranks?
- etc
The comparison is also helpful to get a good grip on important issues related but not limited to proving results: finite vs. infinite plays, separation of rules and strategies, redundancy of rules, etc.

[1] Clerbout, N.: 2013a, ``First-Order Dialogical Games and Tableaux''. To appear in Journal of Philosophical Logic.
[2] Clerbout, N.: 2013b, Etude sur quelques sémantiques dialogiques. Concepts fondamentaux et éléments de metathéorie. PhD dissertation, Lille/Leiden.
[3] Felscher, W.: 1985, ``Dialogues, Strategies, and Intuitionistic Provability''. Annals of Pure and Applied Logic 28, pp. 217-254.
[4] Sorensen, M. and Urzyczyn, P.: 2006, Lectures on the Curry-Howard Isomorphism, Elsevier.
[5] Sorensen, M. and Urzyczyn, P.: 2007, ``Sequent Calculus, Dialogues, and Cut Elimination''. In Barendsen et al. (eds.), Reflections on Type Theory, Lambda Calculus, and the Mind, pp. 253-261.
[6] Uckelman, S.: ``Some remarks on the E-rule in dialogical logic''. Submitted manuscript, available on the author's website.
[7] Uckelman, S., Alama, J. and Knocks, A.: ``A curious dialogical logic and its composition problem''. Submitted manuscript.

Séance de rattrapage le 23 mai

La séance initialement prévue le 16 mai aura lieu le jeudi 23 mai.

Attention, l'horaire n'est pas l'horaire habituel : la séance se tiendra de 11h à 13h - mais le lieu reste le même que d'habitude (Salle Corbin, STL).

Dialogical dialogues are 2*2 matrices of formulas

Pierre Cardascia

Résumé :
The separation of particle rules and structural rules in dialogic causes a strange case of double justification when we try to transfer the dialogical logic in GS.
In my former talk, I spoke about the difference between the local formulation of rules in GS versus the global formulation of dialogical logic, which is the origine of this double justification: in dialogic, one needs (sometimes) to know the entire history of the dialogue to know what moves he can do, and it doesn't fit very well with the compositionality of arenas in GS. To solve that, I made modifications in the formalism (but not so large in the contents), introduced a notion of position, and used it to give another definition of moves (better I hope).

Séance du 16 mai ANNULEE

SEANCE ANNULEE POUR CAUSE DE GREVE DES TRANSPORTS

La séance de remplacement sera annoncée dès que possible

On Abramsky's game semantics 

(continued)

Pierre Cardascia

16 mai 2013, 13h-15h
Salle D. Corbin

Séance du 4 avril

Nature logique ou sémantique de la contradiction chez Aristote : 

le questionnement suscité par les Réfutations Sophistiques

Myriam Hecquet

4 avril 2013, 13h-15h
Salle D. Corbin


Résumé : Dans les Réfutations Sophistiques, l'analyse des paralogismes met en jeu les notions de réfutation (pour toutes les réfutations apparentes), de déduction (pour celles qui ne "tiennent pas à l'expression") et de contradiction (pour celles qui "tiennent à l'expression"), semblant ainsi mettre la contradiction du coté de l'analyse sémantique et réserver l'analyse formelle à la déduction. Pourtant la frontière est perméable et nécessite d'examiner la question de plus près. Cela me permet de revenir sur le rôle de "démonstration par réfutation" du principe de non-contradiction dans Métaphysique Gamma.

Séance du jeudi 21 mars

Dialogue avec des êtres d'un autre type

Matthieu Fontaine

21 mars 2013, 13h-15h
Salle D. Corbin (UMR STL)


Résumé : Dans la théorie artefactuelle, la définition du statut ontologique des entités fictionnelles intègre la notion de dépendance ontologique. S'appuyant sur la sémantique de Fontaine & Rahman [2013] et les premiers développements de Fontaine [2010], l'objectif consiste à définir des relations de dépendances ontologiques dans le contexte de la logique dialogique libre. Pour ce faire, on introduit ces relations dans le langage au moyen de prédicats intentionnels spécifiques, dont la sémantique est donnée par des règles de particules. Certains aspects de telles relations peuvent en fait être capturés en termes de combinaisons de choix opérés lors de l'attaque ou la défense de quantificateurs. Il semblerait sur ce point que les règles de particules qu'on définit pourraient s'apparenter à des règles de formations de prédicats de la théorie des types.

Références

Fontaine, M. 2010. Weak Impermeabilism for Fictionality in a Dialogical Framework, Symposium ``New directions in Dialogical Logics''. 14th CLMPS, Nancy

Fontaine, M. & Rahman, Sh. 2013. ``Towards a Semantics for the Artifactual Theory of Fiction and Beyond (forthcoming)

Séance du 13 décembre 2012

On Abramsky's game semantics

Pierre Cardascia

13 décembre, 13h-15
Attention : salle F0.42 (Maison de la Recherche)


(titre provisoire)

Séance du 15 novembre 2012

A Modal Approach to Theoretical Terms

Matthieu Gallais

15 novembre, 13h-15h
Maison de la recherche, salle F1.07


Abstract:
  The purpose of my presentation is to explain some issues related to the understanding of scientific theories as intrinsically modal constructions. In particular, how can one identify an actual object with a theoretical identity if, for example, that entity has idealized properties according to the theory in which it has been defined? I will suggest a solution which consists in using Hintikka's concept of world-line. The aim is not to replace the original individuating functions, but to develop a second-order function to study the behaviour of properties across possible worlds. Finally, I will show the usefulness of that idea concerning the traditional issue of theoretical terms by revisiting their definitions thanks to world-lines.

Séance du 8 novembre 2012

Game-Theoretical Semantics Generalized

Tero Tulenheimo

8 novembre, 13h-15h
Maison de la Recherche, salle F1.07


Abstract:
   I present a way of generalizing Game-Theoretical Semantics, by enriching positions of games with a new component called `mode'. In connection with certain languages (including IF logic) classical negation becomes game-theoretically interpretable. Ways of capturing certain fragment of higher-order logic in this setting are discussed.

Séance du 18 octobre 2012

Au programme de cette première séance de l'année 2012-2013 :

Learning and inferences: a logical model of a cognitive agent

Christel Grimaud

18 octobre, 13h-15h.
Maison de la Recherche, salle F1.07


Abstract:
     In my talk I will present what I think is a suitable logic for modelling the inferences and learning processes of a cognitive agent.
     First, I will recall the theoretical background of belief revision and non-monotonic inferences. The most influential model for belief revision is the AGM model, called after its three originators, Carlos Alchourron, Peter Gardenfors and David Makinson. However this model suffers from a well-known problem, which is that it doesn't allow iteration. I will recall where does this problem come from, and will consequently argue that the AGM model is not suitable for modelling an agent's learning. In the field of non-monotonic logic, an important account was given by Sarit Kraus, Daniel Lehmann and Menachem Magidor, with a family of logics known as KLM logics or inference relations. Amongst there are the so-called rational consistent inference relations, which have been shown to be strictly equivalent to AGM's belief revision. I will recall this result and will argue that learning must be seen not as a revision of beliefs sets as in the AGM model, but rather as revision of an agent's dispositions to infer. That is, that what are to be revised are the very inference relations. There have been a few attempts in this sense, but non of these seems to be fully satisfying. I will argue that this comes from the fact that rational consistent relations are not the ones which are to be revised, but rather the inference relations of a more general class, which has not been characterized yet. I will present this class of inference relations, and will show how these relations can be revised in a natural and intuitive manner. Then I will present my own attempt to caraterize it.

Séance du 12 avril

Jeudi 12 avril, 11h-13h

Salle Corbin

Abramsky's game semantic and dialogic

Pierre Cardascia

Abstract:

My first presentation in this GdT, "Vers une définition de stratégie sans hypothèse métalogique", began by questioning a metaphoric sentence from Girard: "Game semantics is a fighting sport; but a polite and civilised one: there is an arbiter who prevents nasty moves and bad behaviours. Ludics is more like wrestling: we knocked down the arbiter." I tried to interpret this "arbiter" as "metalogical hypotheses", I exposed some ideas about what should be a strategical behaviour in this context, inspired by different analyses of the Nim games (classic MeX-calculus, categorical analysis, question of the meaning of the cheat.

In my second intervention, "Formalism towards strategical behaviours", I showed the formal problems underlying the precedent talk: materialized players, variable number of players, both legal and illegal moves are possible... It gives us a "research plan". Then I finished by suggesting a "convergence" between the representation of dialogues and the representation of the trace in Abramsky's game semantics (with arenas etc).

For this session, "Abramsky's game semantics and dialogic", I will do more than suggesting, I will construct algorithms of translation between them, thanks to one little but new theorem of "arena-making dialogue":

For each set of particle rules , for each game, there exists a concrete justification [legitimation] such that this game forms a justified sequence of moves in an arena

It shall allow us to implement new results in dialogic (from categorial GS: Abramsky, Hyland, Ong ...) and fulfill the desiderata of the precedent talk. But we won't go too fast: to prove this theorem, I shall present and discuss the concepts of Abramsky's GS.

Séance du 5 avril

Jeudi 5 avril, 11h-13h
Salle D. Corbin

A Dynamic Logic of Interrogative Inquiry

Yacin Hamami

(Vrije Universiteit Brussel)

Abstract :

In this talk, I will propose a dynamic-epistemic analysis of the different epistemic operations constitutive of the process of interrogative inquiry, as described by Hintikka's Interrogative Model of Inquiry (IMI). I will develop a dynamic logic of questions for representing interrogative steps, based on Hintikka's treatment of questions in the IMI, along with a dynamic logic of inferences for representing deductive steps, based on the tableau method. I will then merge these two systems into a dynamic logic of interrogative inquiry which articulates a joint treatment of questions and inferences, providing thereby a unified framework representing the informational dynamics of interrogative inquiry.

I will provide sound and complete axiomatic systems for the three dynamic logics that I introduce, I will compare the framework with existing approaches and I will finally propose several directions for further works. This work is meant as a first step towards linking the IMI with the field of dynamic logics of information and rational agency.

Séance du 15 mars

Jeudi 15 mars, 11h-13h.

Salle Corbin

Husserl on Intentional Attitudes

Giuliano Bacigalupo

Abstract:

In my presentation, I start by addressing the semantics developed by Husserl in his lecture Alte und Neue Logik (1908/9), which may be labelled as "sheres semantics". In the second part, I rely on this semantics as an interpretation grid for Husserl's analysis of intentional attitudes in Ideen I (1913) and argue for an interpretation of the noema as reference to non-actual objects or, what is tantamount to the same, to a non-actual sphere. Thirdly, I address Husserl's discussion of a prosteriori identities in the third section of Ideen I and how this bears on the previous discussion, especially on the notion of object simpliciter. Finally, I turn on the vexed question wether Husserl is a Fregean.

Séance du 16 février

Jeudi 16 février, 11h-13h

Salle Corbin

Playing with or without a list of announcements?

Sébastien Magnier

Abstract:

In a previous presentation, I have argued that a public announcement does not correspond to any conditional connectives. But in fact there are algorithms of translation that turn any public announcement in a conditional way. These translations do not yield an immediate material implication of annoucement propositions. They give us complex or embedded conditionals whose complexity directly depends of the post-condition of the announcement operator. Now, our aim is to compare the dialogues with those propositions (the one with the public announcement operator on the one hand and its corresponding translation on the other hand). As we shall see, such a study underlines the meaning of the list of announcements. This list represents the story of the commitment of the players. It emphasizes the two distinct levels: play and strategy level which occur in the dialogical framework. The comparison between them also suggests some improvements of the rule (SR-A.1) that will probably entail a weakening of the formal rule.

Séance du 2 février 2012

Jeudi 2 février, 11h-13h

Against the so-called “fictional nature” of Law

Juliele Sievers

Abstract:

In my presentation I will try once more to attack the notion of fiction in Law, this time by using some elements of Amie Thomasson’s artefactual theory and Hans Vaihinger’s Philosophy of As-If. Since the first lecture of those works seems to give the idea that norms have the same characteristics of fictions, I will present some arguments against this interpretation. One of them refers to the multiplicity of interpretations of the term “fiction”, which often leads to confusion in its use. Starting by comprehending that the definition of fiction in Literature, in Science and in Law has totally different aspects will lead us to a strong consequence: that the presence of this term in a prescriptive ambit it’s in fact a misuse of it (and we will also understand why this improper practice is nevertheless so widely spread).

Attention : les horaires du GdT ont changé (voir le message ci-dessous).

Dates et Horaire des séances à venir

Changement de semestre et d'emplois du temps obligent, les séances du Groupe de Travail auront désormais lieu à des horaires différents.

Les séances auront lieu de 11 heures à 13 heures les jeudis suivants :

2 février, 16 février.

8 mars, 22 mars.

5 avril, 12 avril.

10 mai, 24 mai.

7 juin, 28 juin.

Séance du 12 décembre

Lundi 12 décembre, 14h-16h

Salle Corbin

The gap in the proof

Nicolas Clerbout

Abstract:

In my last talk I mentionned a result which holds in propositional and first-order dialogical games, namely that the Proponent has a winning strategy in D(F) if and only if he has one in D1(F), where F is a sentence of the relevant language and D1(F) is the subgame of D(F) where the Opponent chooses rank 1.
I also mentionned that there is currently a gap in the proof of the righ-to-left direction. Briefly, the point is that in order to prove this direction we need to prove that if the Opponent cannot win by chosing rank 1 then she cannot win at all.

The aim of this talk is to discuss and hopefully give the proof of that last claim.

Séance du 5 décembre

Lundi 5 décembre, 14 h - 16h,

Salle Corbin

Formalism towards strategical behaviours

Pierre Cardascia

Résumé :

In my last talk I criticized some hypotheses of our approach calling them "meta", and expressed the desire to wipe them out. I had some arguments, but no formal arguments, so my intervention looked like a moment of poetry in a terrible world. I worked a lot, and today I can implement some important notions I spoke about last time. At the end of this talk the strategical reflexion won't be a black box anymore, but will be defined properly as a function from the rules and a project to the strategical behaviour. Then, maybe I will be able to present the notion of orthogonality of behaviours, then show that all the hypotheses I criticize can be reduced into one result of biorthogonality.
After showing that, you will see that I'm a big cheater, because though I can define the "strategical reflexion", it is very nominative, and then, it will be the next problem I have to solve.

Séance du 28 novembre

Comme annoncé précédemment, la séance prévue le 21 novembre aura lieu ce 28 novembre.

Lieu : Salle D. Corbin

Horaire : 14h-16h

Pour rappel, la séance sera consacrée au thème suivant :

Repetition Ranks and Decidability

Nicolas Clerbout

The aim of the talk is to explain how the question of decidability gets manifested in Dialogical Logic. We will see that a clear and concise formulation of the dialogical manifestation of the decidability (or not) of a logic can be given in terms of repetition ranks.

We will consider the cases of Propositional Logic and First-Order Logic.