Talks during the spring term 2017
Wed 18.1.2017 12-14, C124
Juliette Kennedy: Tarski and "the mathematical"
Wed 25.1.2017 12-14, C124
Tapani Hyttinen: On the model theory of Bohr's hydrogen atom
Wed 1.2.2017 12-14, C124
Tim Gendron (University of Cuernavaca): Quantum j-invariant in positive characteristic and Hilbert's 12th problem, Abstract
Wed 8.2.2017 12-14, C124
Tim Gendron (University of Cuernavaca): The modular ultrascheme and the universal modular invariant: towards a proof of Hilbert's 12th problem in characteristic zero, Abstract
Wed 15.2.2017 12.15-13.20, C124
Jouko Väänänen: Dedekind and the problem of categoricity
Wed 22.2.2017 12-14, C124
Juliette Kennedy: Squeezing Arguments and Strong Logics cancelled
Wed 1.3.2017 12-14, C124
Kim Solin: Slow Philosophy of Mathematics
Wed 8.3.2017 12-14, C124
Wed 15.3.2017 12-14, C124
Annika Kanckos: A mathematical context for Gödel's ontological proof
Wed 22.3.2017 12-14, C124
Gianluca Grilletti (Amsterdam): Disjunction and Existence Properties in Inquisitive Logic, Abstract
Wed 29.3.2017 12-14, C124
Miguel Moreno: Reflection principles and Borel reducibility
Wed 5.4.2017 12-14, C124
Juliette Kennedy: Squeezing Arguments and Strong Logics
Wed 12.4.2017 12-14, C124
Jonni Virtema: Polyteam Semantics cancelled
Wed 19.4.2017 12-14, C124
Wed 26.4.2017 12-14, C124
Chris Lambie-Hanson: Reflections on the coloring and chromatic numbers
Abstract: Compactness phenomena play a central role in modern set theory, and the investigation of compactness and incompactness for the coloring and chromatic numbers of graphs has been a thriving area of research since the mid-20th century, when De Bruijn and Erdős published their compactness theorem for finite chromatic numbers. In this talk, we will briefly review some of the highlights in this area and then present new results indicating, firstly, that the coloring number can only exhibit a limited amount of incompactness, and, secondly, that large amounts of incompactness for the chromatic number are compatible with strong compactness statements, including compactness for the coloring number. This indicates that the chromatic and coloring numbers behave quite differently with respect to compactness. This is joint work with Assaf Rinot.
Wed 3.5.2017 12-14, C124
Antti Hyttinen: Statistical Independence in Machine Learning and Causality Research
Abstract: The concept of independence is important part of machine learning, statistics and modern AI research. I will first describe on an intuitive level how independence is represented and used in probabilistic graphical models of machine learning. Then I will talk about causality and intervention, and what complications arise if we want to understand these concepts. This first part builds on the presentation on given in Dagstuhl 2014 seminar for dependence logic. In the final part of I will describe my own research (accepted recently to the IJCAI conference) on learning optimal causal graphs from statistical independence constraints. This work solves a particular causality research problem using a general purpose Boolean optimization solver.
Wed 10.5.2017 12-14, C124
Dag Westerståhl: A Carnapian approach to the meaning of logical constants, Abstract
Yurii Khomskii: "On the bounding number and covering of meager in the generalised Baire space" (joint work with Marlene Koelbing, Giorgio Laguzzi and Wolfgang Wohofsky)
Oskari Kuusela: Wittgenstein’s non-empiricist naturalism in logic
Abstract: In his later philosophy of logic Wittgenstein develops a novel account of the status of logical statements and their non-empirical role. This constitutes a significant departure from his early account of logic, where logic was conceived as abstracting away from anything contingent and empirical (including anything specifically human). On this early account, logic is only concerned with what is necessary and essential to thought and language, whereby this is identified as something common to all possible languages or, in the case of specific expressions, to all expressions capable of expressing a certain sense. By contrast to the strict apriorism of Wittgenstein’s early philosophy of logic, his later account explains 1) how logic can take as its object of investigation contingent (human) forms of language, while retaining its non-empirical character. An important part of the explanation of how this is possible is Wittgenstein’s later account of logical idealization, i.e. how it is possible to describe complex, fluctuating and vague uses of natural language in simple, fixed and exact terms without falsification. Further, 2) logical models in Wittgenstein’s later sense can themselves be based on empirical natural-historical considerations, while their use as logical models is nevertheless clearly distinguished from true/false empirical assertions with reference to the non-temporal use of logical models, as opposed to the temporal use of empirical assertions. This opens up new possibilities for the use of logical methods as instruments of philosophical clarification.
Wed 31.5.2017 12-14, C124
Anselm Haak: Descriptive Complexity and Circuit Complexity
Abstract: In this talk I will give a brief introduction to and overview of descriptive complexity. Furthermore, descriptive complexity results in circuit complexity are presented and discussed, with some special focus on the characterization of the class of functions computable by constant-depth polynomial size arithmetic circuits (with Boolean inputs) and an attempt to connect this characterization to a known characterization of the class #P. Finally, some work in progress is presented: Many important classes from circuit complexity can be characterized with first-order logic extended by a certain kind of recursive predicate definition.