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Logic Seminar

The Logic seminar is held on Wednesdays at 12-14 in C124. After the seminar we have coffee together at 14-15 in the coffee room on the 4th floor.

The seminar is led by prof. Juha Kontinen and university lecturer Juliette Kennedy.

Schedule of the spring term 2020

Wed 15.1.2020 13.00-14, C124
Kaisa Kangas: On groups definable in fields with commuting automorphisms

Wed 22.1.2020 12-14, C124
Joni Puljujärvi: On a Quest to Capture Linear Isomorphism, Part 1: Games on Banach Spaces

Wed 29.1.2020 12-14, C124
Joni Puljujärvi: On a Quest to Capture Linear Isomorphism, Part 2: From Games to Formulas

Wed 5.2.2020 12-14, C124
Jouko Väänänen: Lindström's theorem revisited

Wed 12.2.2020 12-14, C124
Jouko Väänänen: Lindström's theorem revisited (cont.)

Wed 19.2.2020 12-14, C124
Tapio Saarinen: Coloring ladder systems with a weak diamond principle

Wed 26.2.2020 12-14, C124
Edi Pavlovic:
A more unified approach to free logics

Free logics is a family of first-order logics which came about as a result of examining the existence assumptions of classical logic. What those assumptions are varies, but the central ones are that (1) the domain of interpretation is not empty (2) every name denotes exactly one object in the domain and (3) the quantifiers have existential import. Free logics usually reject (2), and of the systems considered in this paper, the positive free logic concedes that some atomic formulas containing non-denoting names, namely self-identity, are true, while negative free logic rejects even the latter claim. Inclusive logics, which reject (1), are likewise briefly considered.

These logics have complex and varied axiomatizations and semantics, and the goal of this paper is to present an orderly examination of the various systems and their mutual relations. This is done by first offering a formalization using sequent calculi, which possess all the desired structural properties of a good proof system, including admissibility of contraction and cut. We then present a simple and unified system of abstract semantics, which allows for a straightforward demonstration of the meta-theoretical properties, and offers insights into the relationship between different systems.

Final part of this paper is dedicated to extending the system with modalities by using a labelled sequent calculus, and here we are again able to map out the different approaches and their mutual relations using the same framework.

This presentation is part of joint work with Norbert Gratzl of MCMP, Munich.

Wed 4.3.2020 12-14, C124
Exam week

Wed 11.3.2020 12-14, C124
Nick Ramsey: Kim-independence over arbitrary sets

Wed 18.3.2020 12-14, C124
Martin Lück: LTBA cancelled

Due to the corona virus situation, the seminar has moved online. Talks will primarily be 1 hour long.

Wed 25.3.2020 13.00-14, Zoom Meeting ID: 733 200 600, https://helsinki.zoom.us/j/733200600
Jouko Väänänen: Fraenkel-Mostowski Models for Dependence Logic

Wed 1.4.2020 13.00-14, C124
Joint Mathematical Physics and Mathematical Logic seminar, Zoom Meeting ID: 726 088 428, https://helsinki.zoom.us/j/726088428
MIP*=RE, Henry Yuen, University of Toronto

What is the connection between Connes' embedding conjecture
from the theory of von Neumann algebras, Tsirelson’s conjecture
in quantum mechanics and theoretical computer science? Using the
methods form the latter the former two conjectures were recently
refuted.

We will watch the recent seminar at IAS, Princeton by
Henry Yuen with the help of local experts here at Helsinki.

Wed 8.4.2020 13-14, C124, Zoom Meeting ID: 321 760 683, https://helsinki.zoom.us/j/321760683
Davide Quadrellaro: Algebraic Semantics for Propositional Dependence Logic

Wed 15.4.2020 13-14, C124
Easter, no seminar

Wed 22.4.2020 12-14, C124
(TBC) Jose Iovino (San Antonio): Compact logics and Tao's concept of metastability

Wed 29.4.2020 12-14, C124
Tuomas Hakoniemi: TBA

Wed 6.5.2020 12-14, C124
Exam week



Talks of the fall term 2019

Talks of the spring term 2019

Talks of the fall term 2018

Talks of the spring term 2018

Talks of the fall term 2017

Talks of the spring term 2017

Talks of the fall term 2016

Talks of the spring term 2016

Talks of the fall term 2015

Talks of the spring term 2015

Talks of the fall term 2014

Talks of the spring term 2014

Talks of the fall term 2013

Talks of the spring term 2013

Talks of the fall term 2012

Older talks (2011-2012)

 

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