Events

Pantelis Eleftheriou, Department of Pure Mathematics, University of Waterloo

“Model-theoretic constructions in many-valued modal logics”

We study a family of Heyting-valued modal logics introduced by Fitting in the early ’90s. For each logic in this family, the semantics is given via Kripke-frames whose edges are labelled with values from an underlying Heyting algebra H.

Ian Payne, Department of Pure Mathematics University of Waterloo

“Continuation of Discrete Homotopy”

I will continue to prove that the operation I defined last week is well defined, and is a group operation. The next step is to define higher homotopy groups, and maybe even do a (very) small example.

Mehdi Radjabalipour, Iranian Academy of Sciences

“Algebraic frames”

The theory of frames (ordinary, generalized, analytic or algebraic frames) is a setting in which one can study signal processing tools such as: Fourier series, Fourier transform, win-dowed Fourier transform, continuous wavelet transforms, etc.

Graham Denham, Western University

“Duality properties for abelian covers”

In parallel with a classical definition due to Bieri and Eckmann, we say an FP group G is an abelian duality group if Hp(G,Z[Gab]) is zero except for a single integer p = n, in which case the cohomology group is torsion-free. We make an analogous definition for spaces.

Mehdi Monfared, University of Windsor

“Involutions and Trivolutions on Second Dual Algebras”

The involution of a C∗-algebra has a nautral extension to its second dual. This is due to the regularity of multiplication in C∗-algebras. In general, for an involutive Banach algebra, not much is known about involutions on A∗∗. Ghahramani and Farhadi have shown that if G has an infinite amenable subgroup, then L1(G)∗∗ does not have any involution extending that of L1(G).

Dima Sinapova, University of Illinois, Chicago

"Powers of singular cardinals"

Cardinal arithmetic has a long history, dating back to Cantor. After the invention of forcing, any reasonable behavior of regular cardinals was shown to be consistent. In contrast, results about singular cardinals are much more intricate and require more than the standard axioms of set theory.

Peter Sinclair, University of Waterloo

"Auxiliary Results on Homotopy Groups and Digraphs"

Abstract: Two weeks ago, we defined a digraph $F^k(X,x_0)$, whose vertices were a particular set of homomorphisms, and a group $\sigma_k(X,x_0)$, whose elements were connected components of $F^k(X,x_0)$. This week, we will begin looking at these structures in more detail.

Nico Spronk, Department of Pure Mathematics, University of Waterloo

"On the subalgebra of a Fourier-Stieltjes algebra generated by pure positive definite functions"

Abstract: For a locally compact group $G$, Yin-Hei Cheng considered the closed subspace $a_0(G)$ which is generated by the pure positive definite

Please note the time

Jessie Yang, McMaster University

Tropical Severi Varieties”

Tropical Geometry is a systematic development of the very well-known fundamental con- cept, “degeneration”. In this talk, I will make this statement precise, focusing on an explicit example, Severi varieties. Severi varieties are classical objects in algebraic geometry which parametrize plane curves with nodal singularities.