# Difference between revisions of "Graduate Logic Seminar"

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=== October 26 - Alice Vidrine === | === October 26 - Alice Vidrine === | ||

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+ | Title: Categorical logic for realizability, part III: Actual realizability | ||

+ | |||

+ | Abstract: Realizability is an approach to semantics for non-classical logic that interprets propositions by sets of abstract computational data. In the present talk we describe the notion of a Schonfinkel algebra (also called a partial combinatory algebra), which gives us a very general notion of computation. We then describe the construction of a topos whose notions of morphism and subobject must respect the computational structure, and describe the unusual features of these toposes, closing with some discussion of Lawvere-Tierney topologies on such toposes. | ||

+ | |||

+ | (The abstracts for parts I and II, which were given in spring 2021, can be found [https://hilbert.math.wisc.edu/wiki/index.php/Graduate_Logic_Seminar,_previous_semesters#March_30_4PM_-_Alice_Vidrine here].) | ||

=== November 9 - Antonio Nákid Cordero === | === November 9 - Antonio Nákid Cordero === |

## Revision as of 19:45, 21 October 2021

The Graduate Logic Seminar is an informal space where graduate students and professors present topics related to logic which are not necessarily original or completed work. This is a space focused principally on practicing presentation skills or learning materials that are not usually presented in a class.

**When:**Tuesdays 4-5 PM**Where:**Van Vleck 901**Organizers:**Jun Le Goh

The talk schedule is arranged at the beginning of each semester. If you would like to participate, please contact one of the organizers.

Sign up for the graduate logic seminar mailing list: join-grad-logic-sem@lists.wisc.edu

## Fall 2021 tentative schedule

To see what's happening in the Logic qual preparation sessions click here.

### September 14 - organizational meeting

We met to discuss the schedule.

### September 28 - Ouyang Xiating

Title: First-order logic, database and consistent query answering

Abstract: Databases are a crucial component of many (if not all) modern applications. In reality, the data stored are often dirty and contain duplicated/missing entries, and it is a natural practice to clean the data first before executing the query. However, the same query might return different answers on different cleaned versions of the dataset. It is then helpful to compute the consistent answers: the query answers that will always be returned, regardless of how the dirty data is cleaned. In this talk, we first introduce the connection between first-order logic and query languages on databases, and then discuss the problem of Consistent Query Answering (CQA): How to compute consistent answers on dirty data? Finally, we show when the CQA problem can be solved using first-order logic for path queries.

### October 12 - Karthik Ravishankar

Title: Notions of randomness for subsets of the Natural Numbers

Abstract: There are a number of notions of randomness of sets of natural numbers. These notions have been defined based on what a 'random object' should behave like such as being 'incompressible' or being 'hard to predict' etc. There is often a interplay between computability and randomness aspects of subsets of natural numbers. In this talk we motivate and present a few different notions of randomness and compare their relative strength.

### October 26 - Alice Vidrine

Title: Categorical logic for realizability, part III: Actual realizability

Abstract: Realizability is an approach to semantics for non-classical logic that interprets propositions by sets of abstract computational data. In the present talk we describe the notion of a Schonfinkel algebra (also called a partial combinatory algebra), which gives us a very general notion of computation. We then describe the construction of a topos whose notions of morphism and subobject must respect the computational structure, and describe the unusual features of these toposes, closing with some discussion of Lawvere-Tierney topologies on such toposes.

(The abstracts for parts I and II, which were given in spring 2021, can be found here.)

### November 9 - Antonio Nákid Cordero

### November 23 - Antonio Nákid Cordero?

### December 7 - John Spoerl

## Previous Years

The schedule of talks from past semesters can be found here.