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Friday, September 30, 2016 3:30 pm - 3:30 pm EDT (GMT -04:00)

“A syntactic characterization”

Mohammad Mahmoud, Department of Pure Mathematics, University of Waterloo

R.i.c.e. relations can be characterized in a purely syntactic way using computably infinitary formulas and without referring to the different copies of the structure. We go through the proof of Theorem II.1.14 that establishes this characterization.

MC 5417

Tuesday, October 18, 2016 3:30 pm - 3:30 pm EDT (GMT -04:00)

“Coding sets of natural numbers into structures”

Jonathan Stephenson, Department of Pure Mathematics, University of Waterloo

We will describe a way to interpret certain r.i.c.e relations as coding sets of natural numbers into structures. Using enumeration reductions, we will give a characterization of the sets of natural numbers which are coded in a structure in terms of the types of the tuples in that structure.

MC 5417

Thursday, October 20, 2016 2:30 pm - 2:30 pm EDT (GMT -04:00)

“Computable structures and computable dimension”

Jonathan Stephenson, Department of Pure Mathematics, University of Waterloo

This seminar will discuss some of the ideas of computable structure theory, which aims to apply computability-theoretic ideas to structures from other areas of mathematics.

Tuesday, October 25, 2016 3:30 pm - 3:30 pm EDT (GMT -04:00)

“Joins of r.i.c.e relations and r.i.c.e complete relations”

Jonathan Stephenson, Department of Pure Mathematics, University of Waterloo

 

We will show that there is a natural way to form both finite and infinite joins of subsets of a structure. We will also introduce r.i.c.e complete relations, and show that every structure has a r.i.c.e. complete relation. We will use this to define a jump operator on relations in structures.

MC 5417

Tuesday, November 15, 2016 3:30 pm - 3:30 pm EST (GMT -05:00)

“The Adjacency Relation”

Jonathan Stephenson, Department of Pure Mathematics, University of Waterloo

 

We will show that the adjacency relation is structurally complete in linear orders, by expressing rice relations in terms of universal sentences over it.

MC 5417