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* '''When:''' Mondays 3:30-4:30 PM
* '''When:''' Mondays 3:30-4:30 PM
* '''Where:''' Van Vleck B223
* '''Where:''' Van Vleck B235
* '''Organizers:''' [https://uriandrews.netlify.app/ Uri Andrews] and [https://sites.google.com/view/hongyu-zhu/ Hongyu Zhu]
* '''Organizer:''' Mariya Soskova


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


Sign up for the graduate logic seminar mailing list:  [mailto:join-grad-logic-sem@lists.wisc.edu join-grad-logic-sem@lists.wisc.edu]
<!--Sign up for the graduate logic seminar mailing list:  [mailto:join-grad-logic-sem@lists.wisc.edu join-grad-logic-sem@lists.wisc.edu]-->


== Fall 2023 ==
== Spring 2025 ==


The seminar will be run as a 1-credit seminar Math 975 in Fall 2023. If you are not enrolled but would like to audit it, please contact [mailto:andrews@math.wisc.edu Uri Andrews] and [mailto:hongyu@math.wisc.edu Hongyu Zhu].
The seminar will be run as a 1-credit seminar Math 975. In Spring 2025, we will finish last semester's topic on Higher Computability Theory.Once we are done students will present a logic topic of their choice (it could be original work, but does not have to be).  If you are not enrolled but would like to audit it, please contact [mailto:soskova@wisc.edu Mariya Soskova].


While you are welcome (and encouraged) to present on a topic of your own choice, feel free to ask for help from faculties and/or other graduate students.
Presentation Schedule: [https://docs.google.com/spreadsheets/d/1uRSaI1edJ5sepz57NV07ohIfBSKL9FgkvJvMAewk1ms/edit?usp=sharing Sign up here.]


Presentation Schedule: https://docs.google.com/spreadsheets/d/15Qd4EzrrKpn1Ct5tur1P_FDc2czsdAVnUf_pfp65Lb4/edit?usp=sharing
Notes on Higher Computability Theory: [https://uwmadison.box.com/s/j3xftdj1i70d4lblxhzswhg9e25ajcpq Download the notes here.] You will need your UW-login. Please, do not distribute these notes without permission from the author.


Zoom link for remote attendance: https://uwmadison.zoom.us/j/96168027763?pwd=bGdvL3lpOGl6QndQcG5RTFUzY3JXQT09 (Meeting ID: 961 6802 7763, Password: 975f23)
<!--Zoom link for remote attendance: https://uwmadison.zoom.us/j/96168027763?pwd=bGdvL3lpOGl6QndQcG5RTFUzY3JXQT09 (Meeting ID: 961 6802 7763, Password: 975f23)-->


Possible readings:
=== '''January 27 - Organizational Meeting and Sapir Ben-Shahar''' ===
* (Elementary) Proof Theory: Chapters 4-7 of <i>[https://projecteuclid.org/ebooks/lecture-notes-in-logic/Aspects-of-Incompleteness/toc/lnl/1235416274 Aspects of Incompleteness]</i> by Per Lindström.
* An invitation to model-theoretic Galois theory.  <i>[https://arxiv.org/abs/0909.4340 On arxiv here.]</i>
* Variations on the Feferman-Vaught Theorem <i>[https://arxiv.org/abs/1812.02905 On arxiv here.]</i>
* Any of several papers on "Turing Computable Embeddings"
* Computability/Model/Set Theory: Consult faculties/students for recommended texts on specific areas.


=== September 11 - Organizational Meeting ===
Mariya Soskova will call for volunteers to sign up for presentations.


We will meet to assign speakers to dates.
Sapir Ben-Shahar will wrap up Section 5.1


=== '''September 18 - Taeyoung Em''' ===
=== '''February 3 - Taeyoung Em''' ===
'''Title:''' Explicit construction of non-quasidetermined game on <math>\mathcal P(2^{\mathbb N})</math> without using A.C. ([https://wiki.math.wisc.edu/images/Gale-Stewart_implies_A.C..pdf Supplement])


'''Abstract:''' We will go over briefly some basic information about trees and infinite games. Then we prove the Gale-Stewart Theorem. The proof of the theorem motivates definition of quasistrategy. Then we will briefly introduce Borel determinacy. We will go over how the usage of A.C. makes convenient for us to make a non-quasidetermined or undertermined game. We will give an explicit construction of a non-quasidetermined game on <math>\mathcal P(2^{\mathbb N})</math> without using A.C.
Taeyoung Em will present Section 5.3.  


=== '''September 25 - Karthik Ravishankar''' ===
=== '''February 10 - Hongyu Zhu''' ===
'''Title:''' Spectra of structures


'''Abstract:''' One way to measure the complexity of a structure is via its spectrum - the set of Turing degrees of its copies. In this talk, we'll look at the definition and first properties of the spectrum followed by some examples. In particular, we'll show that the non-computable degrees and the hyperimmune degrees form a spectrum while the DNC degrees do not.
Hongyu Zhu will present Section 5.3


=== '''October 2 - Hongyu Zhu''' ===
=== '''February 17 - Karthik Ravishankar''' ===
'''Title:''' Continuum Hypothesis: On Platonism and Pluralism ([https://wiki.math.wisc.edu/images/CH.pdf Slides] and [https://uwmadison.zoom.us/rec/share/lSe2BL28988PGmmthWKA6FM7bWOJ0eR6vxP4laS7O6ImNN2gQ5skPJ6-C8KlbGcm.G48mQQ0qlW-lo3gr Recording]; Passcode: .iXJs?1t)


'''Abstract:''' Despite its independence from ZFC, the continuum hypothesis continues to be of interest to logicians. In this talk, we will see arguments for settling the truth of CH in one way or another (or yet another). We will see how mathematical arguments (the inner model program) are intertwined with philosophical beliefs (mathematical Platonism and pluralism) about the set-theoretic universe(s).
'''Title:''' Strong minimal covers and the cupping property


=== '''October 9 - Hannah Ashbach ''' ===
'''Abstract:''' A longstanding question in degree theory has been whether every minimal Turing degree has a strong minimal cover. Meanwhile a strong example of degrees without SMC's are those which have the cupping property. It is known that PA degrees have the cupping property, as do degrees with a certain amount of escaping power. On the other hand, it is known that being weak in the sense of being non DNC and Hyperimmune-free lets you have a SMC. Degrees with the cupping property are closed upwards while it is not known if degrees with SMC are closed downwards. It is also not known if every degree either has the cupping property or a SMC. In this talk we will review several of these results and present techniques used to build SMCs.
'''Title:''' An Introduction to Constructive Mathematics ([https://wiki.math.wisc.edu/images/An_Introduction_to_Constructive_Mathematics.pdf Slides] and [https://uwmadison.zoom.us/rec/share/UIxI2m2WWMnitZTd1oQxYxl6vpashJdvf_2UtN6erlFXN9yNgm7q0mhXw1min0-L.cz3b7tsbBPlsgxD6 Recording]; Passcode: 5.$c5L+2)


'''Abstract:''' Have you ever written a mathematical proof and felt dissatisfied after writing QED? Perhaps you had proven the existence of a particularly complicated mathematical object, but you have no clue how that object may actually look or be constructed. Or perhaps you are ready to denounce the Axiom of Choice after reading about its far-reaching consequences. Constructive logic is a formal logic system that seeks to clear up these concerns for mathematicians, though not all mathematicians agree with the power it holds-- or takes away.
=== '''February 24 -  Hongyu Zhu''' ===


=== '''October 16 - Rune Chen ''' ===
'''Title:''' Seeing the forest does not account for the trees
'''Title:''' An Introduction to Model-Theoretic Galois Theory


'''Abstract:''' Given an arbitrary first-order theory with elimination of imaginaries, the standard Galois theory can be translated into a model-theoretic version, which can be further generalized and thus be useful in other algebraic settings. In this talk, we will give a brief introduction to model-theoretic Galois theory and then look at a simple case of model-theoretic Galois correspondence. We will skip the detailed discussion of elimination of imaginaries by choosing our theory T to be a first-order theory coding finite sets and working in a large enough saturated model M of T.
'''Abstract:''' Say a first-order theory (or a type) has bounded axiomatization if it has an axiomatization by <math>\forall_n</math>-formulas for some finite n. In this talk, we will discuss basic properties of theories and types with (or without) bounded axiomatizations, and in particular whether boundedness of theories implies that of types. (The meaning of the title will be explained in due time.)


=== '''October 23 - John Spoerl ''' ===
=== '''March 3 - Uri Andrews''' ===
'''Title:''' The Computational Content of Forcing


'''Abstract:''' Given information about a ground model, how much can you know about it’s forcing extensions? Given a forcing extension, how much can you know about its ground model? This talk will be a primer on forcing and a review of the main results of Hamkins, Miller and Williams’ 2020 paper: “Forcing as a Computational Process”.
'''Title:''' On the spectra of computable models of disintegrated strongly minimal theories with bounded ranks


=== '''October 30 - Chiara Travesset ''' ===
'''Abstract:''' The spectrum of a strongly minimal theory characterizes which of its countable models have computable copies (indexed by their dimensions). We will focus on the disintegrated strongly minimal theories, i.e., where the algebraic closure of a set is the union of the algebraic closures of the elements of the set.
'''Title:''' Mission-time LTL (MLTL) Formula Validation Via Regular Expressions


'''Abstract:''' Mission-time Linear Temporal Logic (mLTL) is an extension of propositional logic that includes temporal operators over finite intervals of time. A computation is a (finite) sequence consisting of a truth assignment for each propositional variable at each time step. This presentation will describe how we can use regular expressions to describe the structure of the computations that make a given mLTL formula true. We prove soundness and completeness, and also give an implemented algorithm (the WEST program) and analyze its complexity both theoretically and experimentally. We generate a test suite using control flow diagrams to robustly test the code. Finally, we present the REST theorem, which significantly simplifies certain sets of computations. This talk only requires basic familiarity with propositional logic and computer science.
Somewhere in the late aughts, Alice Medvedev and I proved that if a theory is disintegrated strongly minimal and has a finite signature, then either all models are computable, no models are computable, or only the prime model is computable. Steffen Lempp and I tried to push this sort of analysis past finite signatures and we have results about theories which are disintegrated strongly minimal and every symbol in the (infinite) signature has rank less than or equal to 1 in the theory (i.e., you cannot have R(a,b,\bar{z}) if a and b are algebraically independent). Over this past winter break, I found a strategy to bring (some of) this analysis to strongly minimal theories in infinite languages as long as there is some finite N so that every symbol has rank less than or equal to N. I'll describe this strategy, and depending on time, I might even present something that loosely resembles a proof.


=== '''November 6 - Antonio Nakid Cordero ''' ===
=== '''March 10 - Logan Heath''' ===
'''Title:''' TBA


'''Abstract:''' TBA
'''Title:''' Degree Spectra of Theories
 
'''Abstract:''' I will discuss the notion of the degree spectrum of a theory, introduce a class of questions one might ask about such a thing, point to a few of the answers to such questions, and look a little more closely at one such spectrum to highlight the sorts of techniques that arise in the area.
 
 
=== '''March 17 -  Yiqing Wang''' ===
 
'''Title:''' The compactness theorem is overrated
 
'''Abstract:''' Elementary classes, or first-order logic in general, are limited in their ability to capture many natural mathematical classes, such as locally finite groups and Archimedean ordered fields. Conversely, obtaining meaningful results in the generality of non-elementary classes can be impossible. In 1978, Shelah introduced the notion of Abstract Elementary Classes (AECs), providing a framework for studying classes that are not first-order axiomatizable yet still possess rich model-theoretic properties and carry the same 'test question'.
 
In this talk, I will try to give an overview of AECs, prove Shelah’s Presentation Theorem, and highlight some open problems in this area.
 
=== '''March 31 -  Chiara Travesset''' ===
 
'''Title:''' The Sacks Density Theorem
 
'''Abstract:'''  The Sacks Density Theorem states that between any two c.e. degrees, there are two incomparable c.e. degrees. I will present a detailed proof of this theorem.
 
=== '''April 7th -  Taeyoung Em''' ===
 
'''Title:''' Sets that encode themselves
 
'''Abstract:''' Introreducible sets were introduced by Dekker and Myhill. Mansfield proved that complementary retraceable sets are computable and Seetapun and Slaman proved that complementary introreducible sets are computable. In this talk, I will present some results of Appel and McLaughlin on regressive sets, and maybe some other results.
 
=== '''April 21 -  Ang Li???''' ===
 
'''Title:''' tba
 
'''Abstract:''' tba
 
 
== Fall 2024 ==
 
The seminar will be run as a 1-credit seminar Math 975 . In Fall 2024, the topic will be Higher Computability Theory. We will follow notes by Noam Greenberg. If you are not enrolled but would like to audit it, please contact [mailto:soskova@wisc.edu Mariya Soskova].
 
Presentation Schedule: [https://docs.google.com/spreadsheets/d/1ect-dgHdoHOgq4-5BGFiDh6pPThLfDg69Yg__-b_5RY/edit?usp=sharing Sign up here.]
 
Notes: [https://uwmadison.box.com/s/j3xftdj1i70d4lblxhzswhg9e25ajcpq Download the notes here.] You will need your UW-login. Please, do not distribute these notes without permission from the author.
 
<!--Zoom link for remote attendance: https://uwmadison.zoom.us/j/96168027763?pwd=bGdvL3lpOGl6QndQcG5RTFUzY3JXQT09 (Meeting ID: 961 6802 7763, Password: 975f23)-->
 
=== '''September 9 - Organizational Meeting''' ===
 
Mariya Soskova will start with the first sections from the notes.
 
We will then assign speakers to dates and topics.
 
=== '''September 16 -  Sections 1.2-1.4''' ===
 
Kanav Madhura will continue with Sections 1.2-1.4.
 
=== '''September 23 -  Sections 1.3-1.4 and 2.1-2.2''' ===
 
Kanav Madhura will continue with Sections 1.3-1.4. Lucas Duckworth will be ready with Sections 2.1 and 2.2 should there be time.
 
=== '''September 30 -  Sections 2.2 and 2.3-2.5''' ===
 
Lucas Duckworth will finish Section 2.2. Karthik Ravishankar will begin 2.3, 2.4, and 2.5.
=== '''October 7th -  Sections 2.4 and 2.5''' ===
 
Karthik Ravishankar will  finish, 2.4, and 2.5.  Liang Yu will give a talk at 4:00pm.
 
=== '''October 14th -  Sections 2.6 and 2.7''' ===
 
Bjarki Gunnarsson  will present Sections 2.6 and 2.7
 
=== '''October 21th -  Section 3.1''' ===
 
Karthik Ravishankar will present Section 3.1 
 
=== '''October 28th -  Sections 3.2 and 3.3''' ===
 
Karthik Ravishankar will finish Sections 3.2  and John Spoerl will begin Section 3.3
 
=== '''November 4th -  Sections 3.3 and 3.4''' ===
 
John Spoerl will finish Sections 3.3 and 3.4
 
=== '''November 11th -  Section 4.1''' ===


=== '''November 13 - Alice Vidrine ''' ===
Antonion Nakid-Cordero will present Section 4.1
'''Title:''' TBA


'''Abstract:''' TBA
=== '''November 19th -  Sections 4.1 and 4.2''' ===


=== '''November 20 - Logan Heath ''' ===
Start 4:00PM in VV901! Antonion Nakid-Cordero will continue with Section 4.1, Ang Li will begin Section 4.2.
'''Title:''' TBA


'''Abstract:''' TBA


=== November 27 - Thanksgiving Break ===
=== '''November 25th -  Sections 4.2 and 4.3''' ===
'''Title:''' TBA


'''Abstract:''' TBA
Back to the usual time and place. Ang Li will begin Section 4.2.


=== '''December 4 - Ang Li ''' ===
=== '''December 2nd -  Section 4.3''' ===
'''Title:''' TBA


'''Abstract:''' TBA
Ang Li will present Section 4.3.


=== '''December 11 - Mei Rose Connor ''' ===
=== '''December 9nd - Section 5.1''' ===
'''Title:''' TBA


'''Abstract:''' TBA
Last seminar for this semester. Sapir Ben-Shahar will begin Section 5.1


<!-- Template
<!-- Template


=== '''September 18 - Karthik Ravishankar''' ===
=== '''September 18 - xxx''' ===
'''Title:''' Lowness for Isomorphism ([https://wiki.math.wisc.edu/images/Karthik_talk.pdf Slides])
'''Title:''' TBA ([https://wiki.math.wisc.edu/images/***.pdf Slides])


'''Abstract:''' A Turing degree is said to be low for isomorphism if it can only compute an isomorphism between computable structures only when a computable isomorphism already exists. In this talk, we show that the measure of the class of low for isomorphism sets in Cantor space is 0 and that no Martin Lof random is low for isomorphism.
'''Abstract:''' TBA


-->
-->

Latest revision as of 20:59, 1 April 2025

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: Mondays 3:30-4:30 PM
  • Where: Van Vleck B235
  • Organizer: Mariya Soskova

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


Spring 2025

The seminar will be run as a 1-credit seminar Math 975. In Spring 2025, we will finish last semester's topic on Higher Computability Theory.Once we are done students will present a logic topic of their choice (it could be original work, but does not have to be). If you are not enrolled but would like to audit it, please contact Mariya Soskova.

Presentation Schedule: Sign up here.

Notes on Higher Computability Theory: Download the notes here. You will need your UW-login. Please, do not distribute these notes without permission from the author.


January 27 - Organizational Meeting and Sapir Ben-Shahar

Mariya Soskova will call for volunteers to sign up for presentations.

Sapir Ben-Shahar will wrap up Section 5.1

February 3 - Taeyoung Em

Taeyoung Em will present Section 5.3.

February 10 - Hongyu Zhu

Hongyu Zhu will present Section 5.3

February 17 - Karthik Ravishankar

Title: Strong minimal covers and the cupping property

Abstract: A longstanding question in degree theory has been whether every minimal Turing degree has a strong minimal cover. Meanwhile a strong example of degrees without SMC's are those which have the cupping property. It is known that PA degrees have the cupping property, as do degrees with a certain amount of escaping power. On the other hand, it is known that being weak in the sense of being non DNC and Hyperimmune-free lets you have a SMC. Degrees with the cupping property are closed upwards while it is not known if degrees with SMC are closed downwards. It is also not known if every degree either has the cupping property or a SMC. In this talk we will review several of these results and present techniques used to build SMCs.

February 24 - Hongyu Zhu

Title: Seeing the forest does not account for the trees

Abstract: Say a first-order theory (or a type) has bounded axiomatization if it has an axiomatization by [math]\displaystyle{ \forall_n }[/math]-formulas for some finite n. In this talk, we will discuss basic properties of theories and types with (or without) bounded axiomatizations, and in particular whether boundedness of theories implies that of types. (The meaning of the title will be explained in due time.)

March 3 - Uri Andrews

Title: On the spectra of computable models of disintegrated strongly minimal theories with bounded ranks

Abstract: The spectrum of a strongly minimal theory characterizes which of its countable models have computable copies (indexed by their dimensions). We will focus on the disintegrated strongly minimal theories, i.e., where the algebraic closure of a set is the union of the algebraic closures of the elements of the set.

Somewhere in the late aughts, Alice Medvedev and I proved that if a theory is disintegrated strongly minimal and has a finite signature, then either all models are computable, no models are computable, or only the prime model is computable. Steffen Lempp and I tried to push this sort of analysis past finite signatures and we have results about theories which are disintegrated strongly minimal and every symbol in the (infinite) signature has rank less than or equal to 1 in the theory (i.e., you cannot have R(a,b,\bar{z}) if a and b are algebraically independent). Over this past winter break, I found a strategy to bring (some of) this analysis to strongly minimal theories in infinite languages as long as there is some finite N so that every symbol has rank less than or equal to N. I'll describe this strategy, and depending on time, I might even present something that loosely resembles a proof.

March 10 - Logan Heath

Title: Degree Spectra of Theories

Abstract: I will discuss the notion of the degree spectrum of a theory, introduce a class of questions one might ask about such a thing, point to a few of the answers to such questions, and look a little more closely at one such spectrum to highlight the sorts of techniques that arise in the area.


March 17 - Yiqing Wang

Title: The compactness theorem is overrated

Abstract: Elementary classes, or first-order logic in general, are limited in their ability to capture many natural mathematical classes, such as locally finite groups and Archimedean ordered fields. Conversely, obtaining meaningful results in the generality of non-elementary classes can be impossible. In 1978, Shelah introduced the notion of Abstract Elementary Classes (AECs), providing a framework for studying classes that are not first-order axiomatizable yet still possess rich model-theoretic properties and carry the same 'test question'.

In this talk, I will try to give an overview of AECs, prove Shelah’s Presentation Theorem, and highlight some open problems in this area.

March 31 - Chiara Travesset

Title: The Sacks Density Theorem

Abstract: The Sacks Density Theorem states that between any two c.e. degrees, there are two incomparable c.e. degrees. I will present a detailed proof of this theorem.

April 7th - Taeyoung Em

Title: Sets that encode themselves

Abstract: Introreducible sets were introduced by Dekker and Myhill. Mansfield proved that complementary retraceable sets are computable and Seetapun and Slaman proved that complementary introreducible sets are computable. In this talk, I will present some results of Appel and McLaughlin on regressive sets, and maybe some other results.

April 21 - Ang Li???

Title: tba

Abstract: tba


Fall 2024

The seminar will be run as a 1-credit seminar Math 975 . In Fall 2024, the topic will be Higher Computability Theory. We will follow notes by Noam Greenberg. If you are not enrolled but would like to audit it, please contact Mariya Soskova.

Presentation Schedule: Sign up here.

Notes: Download the notes here. You will need your UW-login. Please, do not distribute these notes without permission from the author.


September 9 - Organizational Meeting

Mariya Soskova will start with the first sections from the notes.

We will then assign speakers to dates and topics.

September 16 - Sections 1.2-1.4

Kanav Madhura will continue with Sections 1.2-1.4.

September 23 - Sections 1.3-1.4 and 2.1-2.2

Kanav Madhura will continue with Sections 1.3-1.4. Lucas Duckworth will be ready with Sections 2.1 and 2.2 should there be time.

September 30 - Sections 2.2 and 2.3-2.5

Lucas Duckworth will finish Section 2.2. Karthik Ravishankar will begin 2.3, 2.4, and 2.5.

October 7th - Sections 2.4 and 2.5

Karthik Ravishankar will finish, 2.4, and 2.5. Liang Yu will give a talk at 4:00pm.

October 14th - Sections 2.6 and 2.7

Bjarki Gunnarsson will present Sections 2.6 and 2.7

October 21th - Section 3.1

Karthik Ravishankar will present Section 3.1

October 28th - Sections 3.2 and 3.3

Karthik Ravishankar will finish Sections 3.2 and John Spoerl will begin Section 3.3

November 4th - Sections 3.3 and 3.4

John Spoerl will finish Sections 3.3 and 3.4

November 11th - Section 4.1

Antonion Nakid-Cordero will present Section 4.1

November 19th - Sections 4.1 and 4.2

Start 4:00PM in VV901! Antonion Nakid-Cordero will continue with Section 4.1, Ang Li will begin Section 4.2.


November 25th - Sections 4.2 and 4.3

Back to the usual time and place. Ang Li will begin Section 4.2.

December 2nd - Section 4.3

Ang Li will present Section 4.3.

December 9nd - Section 5.1

Last seminar for this semester. Sapir Ben-Shahar will begin Section 5.1


Previous Years

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

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