# Graduate Logic Seminar: Difference between revisions

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=== September 30 - Josiah Jacobsen-Grocott === | === September 30 - Josiah Jacobsen-Grocott === | ||

Title: Scott Rank of Computable Models | Title: Scott Rank of Computable Models | ||

Abstract: Infinatary logic extends the notions of first order logic by allowing infinite formulas. Scott's Isomorphism Theorem states that any countable structure can be characterized up to isomorphism by a single countable sentence. Closely related to the complexity of this sentence is what is known as the Scott Rank of the structure. In this talk we restrict our attention to computable models and look at an upper bound on the Scott Rank of such structures. | Abstract: Infinatary logic extends the notions of first order logic by allowing infinite formulas. Scott's Isomorphism Theorem states that any countable structure can be characterized up to isomorphism by a single countable sentence. Closely related to the complexity of this sentence is what is known as the Scott Rank of the structure. In this talk we restrict our attention to computable models and look at an upper bound on the Scott Rank of such structures. |

## Revision as of 16:44, 1 October 2019

The Graduate Logic Seminar is an informal space where graduate student and professors present topics related to logic which are not necessarly 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:**Mondays 4p-5p**Where:**Van Vleck B223.**Organizers:**Omer Mermelstein

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 2019 - Tentative schedule

### September 5 - Organizational meeting

### September 9 - No seminar

### September 16 - Daniel Belin

Title: Lattice Embeddings of the m-Degrees and Second Order Arithmetic

Abstract: Lachlan, in a result later refined and clarified by Odifreddi, proved in 1970 that initial segments of the m-degrees can be embedded as an upper semilattice formed as the limit of finite distributive lattices. This allows us to show that the many-one degrees codes satisfiability in second-order arithmetic, due to a later result of Nerode and Shore. We will take a journey through Lachlan's rather complicated construction which sheds a great deal of light on the order-theoretic properties of many-one reducibility.

### September 23 - Daniel Belin

Title: Lattice Embeddings of the m-Degrees and Second Order Arithmetic - Continued

### September 30 - Josiah Jacobsen-Grocott

Title: Scott Rank of Computable Models

Abstract: Infinatary logic extends the notions of first order logic by allowing infinite formulas. Scott's Isomorphism Theorem states that any countable structure can be characterized up to isomorphism by a single countable sentence. Closely related to the complexity of this sentence is what is known as the Scott Rank of the structure. In this talk we restrict our attention to computable models and look at an upper bound on the Scott Rank of such structures.

### October 7 - Josiah Jacobsen-Grocott

Title: Scott Rank of Computable Codels - Continued

### October 14 - Tejas Bhojraj I - Date may change

### October 21 - Tejas Bhojraj II - Date may change

### October 28 - Two short talks

Iván Ongay Valverde and James Earnest Hanson

### November 4 - Two short talks

Speakers TBD

### November 11 - Manlio Valenti I

### November 18 - Manlio Valenti II

### November 25 - Two short talks

Speakers TBD

### December 2 - Iván Ongay Valverde I

### December 9 - Iván Ongay Valverde II

## Previous Years

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