Barcelona Set theory Seminar
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
This Week in Logic at CUNY
Date: Monday, October 25, 4.156.15 (NY time)
Noah FriedmanBiglin (San José State University)
Title: Regrounding the Unworldly: Pluralism and Politics in Carnap’s Philosophy of Logic
Abstract: The locus classicus of logical pluralism – that is, the view that there is more than on logic, properly so called – since the earliest days of analytic philosophy, can be found in Rudolf Carnap’s ‘principle of tolerance’. Clarifying the principle of tolerance is the focus of this first section of this paper. I will argue that the principle should be understood as widely as possible, and thus we will see that Carnap’s tolerance is a very radical view. In section two, I discuss the motivations Carnap had for his pluralism, and argue that they are based in the Vienna Circle’s “Scientific WorldConception” — a platform of philosophical commitments which set the direction for the Circle’s philosophical investigations as well as a program of social change. What emerges from this discussion is the oftenignored relationship between his logical pluralism and his political views. In short, I will argue that the radical quality of his tolerance is due to these political commitments. In section three, I examine the reasons why this connection is not very wellknown. I will argue that the political situation in the United States in the aftermath of World War 2 created conditions where it was dangerous to explicitly link scholarly work and politics, and discuss the reasons that Carnap might have had for distancing himself from – or at least deemphasizing – the political foundations of his views.
Computational Logic seminar
For a zoom link, contact Sergei Artemov (sartemov@gc.cuny.edu)
Title: On logical foundations of strategic games
Abstract: In his dissertation of 1950, Nash based his concept of solution to a game on the principles that "a rational prediction should be unique, that the players should be able to deduce and make use of it." Nash noticed that such a definitive solution is always a Nash Equilibrium (NE). We observe that, for the basic notion of Aumann's rationality, NE, even if it is unique, is not necessarily Nash's definitive solution. We show that the Iterated Deletion of Strictly Dominated Strategies is a complete procedure for Nash's definitive solution for strategic games.
    Wednesday, Oct 27, 2021    
    Thursday, Oct 28, 2021    
    Friday, Oct 29, 2021    
CUNY Graduate Center, Room 6417
Friday, October 29, 2pm
Potentialism about classes
    Monday, Nov 1, 2021    
Models of Peano Arithmetic (MOPA)
Monday, October 25th, 2pm
The seminar will take place virtually at 2pm US Eastern Standard Time. Please email Victoria Gitman (vgitman@nylogic.org) for meeting id.
Fedor Pakhomov Ghent University
Logic and Metaphysics Workshop
Date: Monday, November 1, 4.156.15 (NY time)
For meeting information, please sign up for our mailing list at https://logic.commons.gc.cuny.edu/about/
The SubjectMatter of Modal Sentences
The framework of topicsensitive intentional modal operators (TSIMs) described by Berto provides a general platform for representing agents' intentional states of various kinds. For example, a TSIM can model doxastic states, capturing a notion that given the acceptance of antecedent information P, an agent will have a consequent belief Q. Notably, the truth conditions for TSIMs include a subjectmatter filter so that the topic of the consequent Q must be "included" within that of the antecedent. To extend the account to languages with richer expressivity thus requires an expanded account of subjectmatter. In this talk, I will discuss extending earlier work on the subjectmatter of intensional conditionals to the special case of modal sentences whose primary operators are interpreted by possible worlds semantics.
    Tuesday, Nov 2, 2021    
    Wednesday, Nov 3, 2021    
    Thursday, Nov 4, 2021    
    Friday, Nov 5, 2021    
CUNY Graduate Center, Room 6417
Friday, November 5, 2pm
Tom Benhamou, Tel Aviv University
Intermediate Prikrytype models, quotients, and the Galvin property
We classify intermediate models of MagidorRadin generic extensions. It turns out that similar to Gitik Kanovei and Koepke's result, every such intermediate model is of the form where is a subsequence of the generic club added by the forcing. The proof uses the Galvin property for normal filters to prove that quotients of some Prikrytype forcings are c.c. in the generic extension and therefore do not add fresh subsets to . If time permits, we will also present results regarding intermediate models of the TreePrikry forcing.
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Damian Głodkowski; The poset of projections in the Calkin algebra, cont.
Next CMU math logic seminar (special time)
Wednesday seminar
Logic Seminar Wed 27 Oct 2021 17:00 hrs at NUS by Mars Yamaleev
UPDATE: This Week in Logic at CUNY
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
New URL: http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Title: Out of Sample Generalization with Kan Extensions.
Abstract: A common problem in data science is use this function defined over this small set to generate predictions over that larger set. Extrapolation, interpolation, statistical inference and forecasting all reduce to this problem. The Kan extension is a powerful tool in category theory that generalizes this notion. In this work we explore several applications of Kan extensions to data science.
    Thursday, Oct 21, 2021    
    Friday, Oct 22, 2021    
Friday, October 22, 2:003:30pm
    Monday, Oct 25, 2021    
Date: Monday, October 25, 4.156.15 (NY time)
Noah FriedmanBiglin (San José State University)
Title: Regrounding the Unworldly: Pluralism and Politics in Carnap’s Philosophy of Logic
Abstract: The locus classicus of logical pluralism – that is, the view that there is more than on logic, properly so called – since the earliest days of analytic philosophy, can be found in Rudolf Carnap’s ‘principle of tolerance’. Clarifying the principle of tolerance is the focus of this first section of this paper. I will argue that the principle should be understood as widely as possible, and thus we will see that Carnap’s tolerance is a very radical view. In section two, I discuss the motivations Carnap had for his pluralism, and argue that they are based in the Vienna Circle’s “Scientific WorldConception” — a platform of philosophical commitments which set the direction for the Circle’s philosophical investigations as well as a program of social change. What emerges from this discussion is the oftenignored relationship between his logical pluralism and his political views. In short, I will argue that the radical quality of his tolerance is due to these political commitments. In section three, I examine the reasons why this connection is not very wellknown. I will argue that the political situation in the United States in the aftermath of World War 2 created conditions where it was dangerous to explicitly link scholarly work and politics, and discuss the reasons that Carnap might have had for distancing himself from – or at least deemphasizing – the political foundations of his views.
Models of Peano Arithmetic (MOPA)
Monday, October 25th, 2pm
The seminar will take place virtually at 2pm US Eastern Standard Time. Please email Victoria Gitman (vgitman@nylogic.org) for meeting id.
Fedor Pakhomov Ghent University
    Wednesday, Oct 27, 2021    
    Thursday, Oct 28, 2021    
    Friday, Oct 29, 2021    
CUNY Graduate Center, Room 6417
Friday, October 29, 2pm
Potentialism about classes
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
This Week in Logic at CUNY
Date: Monday, October 18, 4.156.15 (NY time)
Rohit Parikh (CUNY GC).
Title: States of Knowledge
Abstract: We know from long ago that among a group of people and given a true proposition P, various states of knowledge of P are possible. The lowest is when no one knows P and the highest is when P is common knowledge. The notion of common knowledge is usually attributed to David Lewis, but it was independently discovered by Schiffer. There are indications of it also in the doctoral dissertation of Robert Nozick. Aumann in his celebrated Agreeing to Disagree paper is generally thought to be the person to introduce it into game theory. But what are the intermediate states? It was shown by Pawel Krasucki and myself that there are only countably many and they correspond to what S. C. Kleene called regular sets. But different states of knowledge can cause different group actions. If you prefer restaurant A to B and so do I, and it is common knowledge, and we want to eat together, then we are likely to both go to A. But without that knowledge we might end up in B, or one in A and one in B. This was discussed by Thomas Schelling who also popularized the notion of focal points. Do different states of knowledge always lead to different group actions? Or can there be distinct states which cannot be distinguished through action? The question seems open. It obviously arises when we try to infer the states of knowledge of animals by witnessing their actions. We will discuss the old developments as well as some more recent ideas.
    Tuesday, Oct 19, 2021    
    Wednesday, Oct 20, 2021    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
New URL: http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Title: Out of Sample Generalization with Kan Extensions.
Abstract: A common problem in data science is use this function defined over this small set to generate predictions over that larger set. Extrapolation, interpolation, statistical inference and forecasting all reduce to this problem. The Kan extension is a powerful tool in category theory that generalizes this notion. In this work we explore several applications of Kan extensions to data science.
    Thursday, Oct 21, 2021    
    Friday, Oct 22, 2021    
Friday, October 22, 2:003:30pm
    Monday, Oct 25, 2021    
Date: Monday, October 25, 4.156.15 (NY time)
Noah FriedmanBiglin (San José State University)
Title: Regrounding the Unworldly: Pluralism and Politics in Carnap’s Philosophy of Logic
Abstract: The locus classicus of logical pluralism – that is, the view that there is more than on logic, properly so called – since the earliest days of analytic philosophy, can be found in Rudolf Carnap’s ‘principle of tolerance’. Clarifying the principle of tolerance is the focus of this first section of this paper. I will argue that the principle should be understood as widely as possible, and thus we will see that Carnap’s tolerance is a very radical view. In section two, I discuss the motivations Carnap had for his pluralism, and argue that they are based in the Vienna Circle’s “Scientific WorldConception” — a platform of philosophical commitments which set the direction for the Circle’s philosophical investigations as well as a program of social change. What emerges from this discussion is the oftenignored relationship between his logical pluralism and his political views. In short, I will argue that the radical quality of his tolerance is due to these political commitments. In section three, I examine the reasons why this connection is not very wellknown. I will argue that the political situation in the United States in the aftermath of World War 2 created conditions where it was dangerous to explicitly link scholarly work and politics, and discuss the reasons that Carnap might have had for distancing himself from – or at least deemphasizing – the political foundations of his views.
Models of Peano Arithmetic (MOPA)
Monday, October 25th, 2pm
The seminar will take place virtually at 2pm US Eastern Standard Time. Please email Victoria Gitman (vgitman@nylogic.org) for meeting id.
Fedor Pakhomov Ghent University
    Wednesday, Oct 27, 2021    
    Thursday, Oct 28, 2021    
    Friday, Oct 29, 2021    
CUNY Graduate Center, Room 6417
Friday, October 29, 2pm
Potentialism about classes
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
Barcelona Set theory Seminar
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Damian Głodkowski; The poset of projections in the Calkin algebra
Logic Seminar Wed 20 Oct 2021 16:00 hrs at NUS by Yang Yue
(KGRC) seminar talks on Tuesday, October 19 and Thursday, October 21
Talks next Tuesday
Wednesday seminar
Logic Seminar Wednesday 13 October 2021 16:00 hrs at NUS by Liao Yuke
This Week in Logic at CUNY
*** GRAD CENTER CLOSED TODAY ***
    Tuesday, Oct 12, 2021    
Computational Logic Seminar
Tuesday October 12, 2021, 24pm
For a zoom link, contact Sergei Artemov (sartemov@gc.cuny.edu)
    Wednesday, Oct 13, 2021    
    Thursday, Oct 14, 2021    
    Friday, Oct 15, 2021    
CUNY Graduate Center, Room 6417
Friday, October 1
    Monday, Oct 18, 2021    
Date: Monday, October 4, 4.156.15 (NY time)
Rohit Parikh (CUNY GC).
Title: States of Knowledge
Abstract: We know from long ago that among a group of people and given a true proposition P, various states of knowledge of P are possible. The lowest is when no one knows P and the highest is when P is common knowledge. The notion of common knowledge is usually attributed to David Lewis, but it was independently discovered by Schiffer. There are indications of it also in the doctoral dissertation of Robert Nozick. Aumann in his celebrated Agreeing to Disagree paper is generally thought to be the person to introduce it into game theory. But what are the intermediate states? It was shown by Pawel Krasucki and myself that there are only countably many and they correspond to what S. C. Kleene called regular sets. But different states of knowledge can cause different group actions. If you prefer restaurant A to B and so do I, and it is common knowledge, and we want to eat together, then we are likely to both go to A. But without that knowledge we might end up in B, or one in A and one in B. This was discussed by Thomas Schelling who also popularized the notion of focal points. Do different states of knowledge always lead to different group actions? Or can there be distinct states which cannot be distinguished through action? The question seems open. It obviously arises when we try to infer the states of knowledge of animals by witnessing their actions. We will discuss the old developments as well as some more recent ideas.
    Tuesday, Oct 19, 2021    
    Wednesday, Oct 20, 2021    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
New URL: http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Title: Out of Sample Generalization with Kan Extensions.
Abstract: A common problem in data science is use this function defined over this small set to generate predictions over that larger set. Extrapolation, interpolation, statistical inference and forecasting all reduce to this problem. The Kan extension is a powerful tool in category theory that generalizes this notion. In this work we explore several applications of Kan extensions to data science.
    Thursday, Oct 21, 2021    
    Friday, Oct 22, 2021    
Friday, October 22, 2:003:30pm
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
UPDATE  This Week in Logic at CUNY
    Monday, Oct 4, 2021    
Penn Logic and Computation Seminar
Monday, October 4, 3:30 pm US Eastern, online
Speaker: Sergei Artemov, CUNY Graduate Center
Title: Missing Proofs and the Provability of Consistency
The link will be available by 12 noon on Monday. To get it, contact Andre Scedrov <scedrov@math.upenn.edu> or Sergei Artemov <sartemov@gc.cuny.edu>.
Date: Monday, October 4, 4.156.15 (NY time)
Abstract: In this talk, I consider modal logics extending J (intuitionistic logic) and RMO (sometimes called ‘constructive mingle’). Adapting previous work of Humberstone, all of these systems are given a purely operational bisemilattice semantics and soundness and completeness results are proved. I consider a way of exactly translating each intuitionistic modal system into a relevant modal companion and discuss what, if any, light this sheds on the interpretation of the relevant companions. Various applications are examined (e.g., to developing constructive theories of entailment) and results germane to those applications are proved. I also discuss connections between the present semantic framework and related frameworks, including Fine’s hybrid operationalpartial order semantics, inquisitive semantics, and Urquhart’s semilattice semantics.
    Tuesday, Oct 5, 2021    
Computational Logic Seminar
Tuesday October 5, 2021, 24pm
For a zoom link, contact Sergei Artemov (sartemov@gc.cuny.edu)
Speaker: Noson Yanofsky, CUNY
Title: Diagonalization, Fixed Points, and Selfreference
    Wednesday, Oct 6, 2021    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
New URL: http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Date and Time: Wednesday October 6, 2021, 7:00  8:30 PM., on Zoom.
Title: From simplicity to universality and undecidability.
Abstract: Why is it so easy to generate complexity? I will suggest that this is due to the phenomenon of universality — essentially every nontrivial system is universal, and thus able to explore all complexity in its domain. We understand universality in spin models, automata and neural networks. I will present the first step toward rigorously linking the first two, where we cast classical spin Hamiltonians as formal languages and classify the latter in the Chomsky hierarchy. We prove that the language of (effectively) zerodimensional spin Hamiltonians is regular, onedimensional spin Hamiltonians is deterministic contextfree, and higherdimensional and alltoall spin Hamiltonians is contextsensitive. I will also talk about the other side of the coin of universality, namely undecidability, and will raise the question of whether universality is visible in Lawvere’s Theorem.
    Thursday, Oct 7, 2021    
Thursday, October 7, 6:30 PM
A Zoom link will be posted Wednesday on https://philog.arthurpaulpedersen.org/
Negative probabilities: What are they for?
Yuri Gurevich, University of Michigan
The topic may sound nonsensical. The standard frequential interpretation of probabilities makes no sense for negative probabilities. Yet negative probabilities are profitably used in quantum physics and elsewhere. So what are they? What is their intrinsic meaning? We don't know. There are attempts in the literature to provide meaning for negative probabilities but, in our judgement, the problem is wide open.
Instead, we address a more pragmatic question: What are negative probabilities good for? It is not rare in science to use a concept without understanding its intrinsic meaning. Consider early uses of complex numbers. The standard quantitative interpretation of numbers makes no sense for imaginary numbers. And the intrinsic meaning of imaginary numbers wasn't clear (and is debatable even today). Yet complex numbers were profitably used to solve algebraic equations. It turned out, for example, that many real algebraic numbers cannot be
expressed in radicals unless we allow nonreal complex coefficients.
It turns out that the disparate quantum applications of negative probabilities can be seen as examples of a certain application template. To make this template explicit, we introduce observation spaces. An observation space S is a family of (nonnegative) probability distributions P1, P2, ... on a common sample space. A question arises whether there is a single probability distribution P (a grounding for S) which yields all P1, P2, ... as marginal distributions. That P may be necessarily signed. We solve the grounding problem for a number of observation spaces of note.
The talk is based on a recent paper with Andreas Blass in J. Phys. A.
    Friday, Oct 8, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 8
Brent Cody, Virginia Commonwealth University
By beginning with the order topology on an ordinal , and iteratively declaring more and more derived sets to be open, Bagaria defined the derived topologies on , where is an ordinal. He showed that the nonisolated points in the space can be characterized using a strong form of iterated simultaneous stationary reflection called sreflection, which is deeply connected to certain transfinite indescribability properties. However, Bagaria's definitions break for because, under his definitions, the th derived topology is discrete and no ordinal can be sstationary. We will discuss some new work in which we use certain diagonal versions of Bagaria's definitions to extend his results. For example, we introduce the notions of diagonal Cantor derivative and use it to obtain a sequence of derived topologies on a regular that is strictly longer than that of Bagaria's, under certain hypotheses.
Next Week in Logic at CUNY:
    Monday, Oct 11, 2021    
    Tuesday, Oct 12, 2021    
    Wednesday, Oct 13, 2021    
    Thursday, Oct 14, 2021    
    Friday, Oct 15, 2021    
CUNY Graduate Center, Room 6417
Friday, October 1
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
This Week in Logic at CUNY
    Monday, Oct 4, 2021    
Penn Logic and Computation Seminar
Monday, October 4, 3:30 pm US Eastern, online
Speaker: Sergei Artemov, CUNY Graduate Center
Title: Missing Proofs and the Provability of Consistency
The link will be available by 12 noon on Monday. To get it, contact Andre Scedrov <scedrov@math.upenn.edu> or Sergei Artemov <sartemov@gc.cuny.edu>.
Date: Monday, October 4, 4.156.15 (NY time)
Abstract: In this talk, I consider modal logics extending J (intuitionistic logic) and RMO (sometimes called ‘constructive mingle’). Adapting previous work of Humberstone, all of these systems are given a purely operational bisemilattice semantics and soundness and completeness results are proved. I consider a way of exactly translating each intuitionistic modal system into a relevant modal companion and discuss what, if any, light this sheds on the interpretation of the relevant companions. Various applications are examined (e.g., to developing constructive theories of entailment) and results germane to those applications are proved. I also discuss connections between the present semantic framework and related frameworks, including Fine’s hybrid operationalpartial order semantics, inquisitive semantics, and Urquhart’s semilattice semantics.
    Tuesday, Oct 5, 2021    
Computational Logic Seminar
Tuesday October 5, 2021, 24pm
For a zoom link, contact Sergei Artemov (sartemov@gc.cuny.edu)
Speaker: Noson Yanofsky, CUNY
Title: Diagonalization, Fixed Points, and Selfreference
    Wednesday, Oct 6, 2021    
Department of Computer Science
Department of Mathematics
The Graduate Center of The City University of New York
New URL: http://www.sci.brooklyn.cuny.edu/~noson/Seminar/index.html
Date and Time: Wednesday October 6, 2021, 7:00  8:30 PM., on Zoom.
Title: From simplicity to universality and undecidability.
Abstract: Why is it so easy to generate complexity? I will suggest that this is due to the phenomenon of universality — essentially every nontrivial system is universal, and thus able to explore all complexity in its domain. We understand universality in spin models, automata and neural networks. I will present the first step toward rigorously linking the first two, where we cast classical spin Hamiltonians as formal languages and classify the latter in the Chomsky hierarchy. We prove that the language of (effectively) zerodimensional spin Hamiltonians is regular, onedimensional spin Hamiltonians is deterministic contextfree, and higherdimensional and alltoall spin Hamiltonians is contextsensitive. I will also talk about the other side of the coin of universality, namely undecidability, and will raise the question of whether universality is visible in Lawvere’s Theorem.
    Thursday, Oct 7, 2021    
    Friday, Oct 8, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 8
Brent Cody, Virginia Commonwealth University
By beginning with the order topology on an ordinal , and iteratively declaring more and more derived sets to be open, Bagaria defined the derived topologies on , where is an ordinal. He showed that the nonisolated points in the space can be characterized using a strong form of iterated simultaneous stationary reflection called sreflection, which is deeply connected to certain transfinite indescribability properties. However, Bagaria's definitions break for because, under his definitions, the th derived topology is discrete and no ordinal can be sstationary. We will discuss some new work in which we use certain diagonal versions of Bagaria's definitions to extend his results. For example, we introduce the notions of diagonal Cantor derivative and use it to obtain a sequence of derived topologies on a regular that is strictly longer than that of Bagaria's, under certain hypotheses.
Next Week in Logic at CUNY:
    Monday, Oct 11, 2021    
    Tuesday, Oct 12, 2021    
    Wednesday, Oct 13, 2021    
    Thursday, Oct 14, 2021    
    Friday, Oct 15, 2021    
CUNY Graduate Center, Room 6417
Friday, October 1
    Other Logic News    
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
(KGRC) Set Theory Research Seminar talk on Tuesday, October 5
Two events on October 5
Wednesday seminar
Logic Seminar 6 Oct 2021 16:00 hrs at NUS by Chong Chitat
This Week in Logic at CUNY  UPDATE
Computational Logic Seminar
Tuesday September 28, 2021, 24pm
For a zoom link, contact Sergei Artemov (sartemov@gc.cuny.edu)
Speaker: Melvin Fitting, CUNY Graduate Center
Title: Admitting the Empty Domain
This talk is about classical logic. But the same issues come up for intuitionistic logic, modal logics, paraconsistent logics, and so on. Nobody seems to have looked at what happens. At the heart of it all, the original question that prompted the investigations of the 1960’s still remains: why should the existence of something be taken as a logical truth?
    Wednesday, Sep 29, 2021    
    Thursday, Sep 30, 2021    
    Friday, Oct 01, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 1
Matteo Viale, University of Torino
Absolute model companionship, forcibility, and the continuum problem: Part II
Absolute model companionship (AMC) is a strengthening of model companionship defined as follows: For a theory , denotes the logical consequences of which are boolean combinations of universal sentences. is the AMC of if it is model complete and . The theory of algebraically closed field is the model companion of the theory of but not its AMC as . Any model complete theory is the AMC of . We use AMC to study the continuum problem and to gauge the expressive power of forcing. We show that (a definable version of) is the unique solution to the continuum problem which can be in the AMC of a partial Morleyization of the theory there are class many supercompact cardinals. We also show that (assuming large cardinals) forcibility overlaps with the apparently weaker notion of consistency for any mathematical problem expressible as a sentence of a (very large fragment of) third order arithmetic (, the Suslin hypothesis, the Whitehead conjecture for free groups are a small sample of such problems ). Partial Morleyizations can be described as follows: let be the set of first order formulae; for , is the expansion of adding atomic relation symbols for all formulae in and is the theory asserting that each formula is logically equivalent to the corresponding atomic formula . For a theory is the partial Morleyization of induced by .
Next Week in Logic at CUNY:
    Monday, Oct 4, 2021    
Date: Monday, October 4, 4.156.15 (NY time)
    Tuesday, Oct 5, 2021    
    Wednesday, Oct 6, 2021    
    Thursday, Oct 7, 2021    
    Friday, Oct 8, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 8
Brent Cody, Virginia Commonwealth University
    Other Logic News    
ANNOUNCEMENT  Carl Posy  Working Group on Intuitionism
I am assembling a working group on intuitionism. We aim eventually to explore the philosophical ground of intuitionistic mathematics. We will ultimately look at issues in philosophy of mind (including phenomenology), epistemology, ontology and semantics. However, in order to do so, we will begin with in depth studies of intuitionistic mathematics and intuitionistic logic.
Participation in the group will provide the needed background for someone who would like to develop large or small projects related to some aspect of intuitionism (mathematics, logic or philosophy). The group will also serve those who are interested simply in acquiring a working knowledge of intuitionism per se.
Our initial studies of intuitionistic mathematics and logic will roughly follow the organization of the first chapters of my recent book Mathematical Intuitionism. However, we will refine, correct and expand the material in the book. There’ll be references and material for those who would like to pursue some topic or other even further.
The group invites both participants with some limited or even extensive background in intuitionism and those without any background in intuitionism but with an interest in learning about intuitionism and/or working on related research aims. Some knowledge of mathematics (in particular of elementary real analysis) and/or logic (in particular through basic philosophical logic) is desirable.
The group will have regularly scheduled meetings no more frequently than twice a month, during the academic year. We will set a schedule at the start of each year.
The current plan is to function for at least two or three academic years. Sometime in the second or third year we will have a conference including members and outside researchers. We will begin in late 2021 or early 2022.
From time to time will also have guest lectures from prominent researchers.
From time to time active members will prepare and present material  appropriate to their background and interests.
Anyone interested should contact me at: carl.posy@mail.huji.ac.il We will then arrange a time to speak.
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
 ADMINISTRIVIA 
To subscribe/unsubscribe to this list, please email your request to jreitz@nylogic.org.
If you have a logicrelated event that you would like included in future mailings, please email jreitz@nylogic.org.
This Week in Logic at CUNY
    Monday, Sep 27, 2021    
Date: Monday, September 27, 4.156.15 (NY time)
Title: A Recipe for Paradox: A Better Schema than the Inclosure Schema
Abstract: In this talk, we provide a recipe that not only captures the common structure between semantic paradoxes but it also captures our intuitions regarding the relations between these paradoxes. Before we unveil our recipe, we first talk about a popular schema introduced by Graham Priest, namely, the inclosure schema. Without rehashing previous arguments against the inclosure schema, we contribute different arguments for the same concern that the inclosure schema bundles the wrong paradoxes together. That is, we will provide alternative arguments on why the inclosure schema is both too broad for including the Sorites paradox, and too narrow for excluding Curry’s paradox. We then spell out our recipe. Our recipe consists of three ingredients: (1) a predicate that has two specific rules, (2) a simple method to find a partial negative modality, and (3) a diagonal lemma that would allow us to let sentences be their partial negative modalities. The recipe shows that all of the following paradoxes share the same structure: The liar, Curry’s paradox, Validity Curry, Provability Liar, a paradox leading to Löb’s theorem, Knower’s paradox, Knower’s Curry, GrellingNelson’s paradox, Russell’s paradox in terms of extensions, alternative liar and alternative Curry, and other unexplored paradoxes. We conclude the talk by stating the lessons that we can learn from the recipe, and what kind of solutions does the recipe suggest if we want to adhere to the Principle of Uniform Solution.
    Tuesday, Sep 28, 2021    
    Wednesday, Sep 29, 2021    
    Thursday, Sep 30, 2021    
    Friday, Oct 01, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 1
Matteo Viale, University of Torino
Absolute model companionship, forcibility, and the continuum problem: Part II
Absolute model companionship (AMC) is a strengthening of model companionship defined as follows: For a theory , denotes the logical consequences of which are boolean combinations of universal sentences. is the AMC of if it is model complete and . The theory of algebraically closed field is the model companion of the theory of but not its AMC as . Any model complete theory is the AMC of . We use AMC to study the continuum problem and to gauge the expressive power of forcing. We show that (a definable version of) is the unique solution to the continuum problem which can be in the AMC of a partial Morleyization of the theory there are class many supercompact cardinals. We also show that (assuming large cardinals) forcibility overlaps with the apparently weaker notion of consistency for any mathematical problem expressible as a sentence of a (very large fragment of) third order arithmetic (, the Suslin hypothesis, the Whitehead conjecture for free groups are a small sample of such problems ). Partial Morleyizations can be described as follows: let be the set of first order formulae; for , is the expansion of adding atomic relation symbols for all formulae in and is the theory asserting that each formula is logically equivalent to the corresponding atomic formula . For a theory is the partial Morleyization of induced by .
Next Week in Logic at CUNY:
    Monday, Oct 4, 2021    
Date: Monday, October 4, 4.156.15 (NY time)
    Tuesday, Oct 5, 2021    
    Wednesday, Oct 6, 2021    
    Thursday, Oct 7, 2021    
    Friday, Oct 8, 2021    
Set Theory Seminar
CUNY Graduate Center, Room 6417
Friday, October 8
Brent Cody, Virginia Commonwealth University
    Other Logic News    
ANNOUNCEMENT  Carl Posy  Working Group on Intuitionism
I am assembling a working group on intuitionism. We aim eventually to explore the philosophical ground of intuitionistic mathematics. We will ultimately look at issues in philosophy of mind (including phenomenology), epistemology, ontology and semantics. However, in order to do so, we will begin with in depth studies of intuitionistic mathematics and intuitionistic logic.
Participation in the group will provide the needed background for someone who would like to develop large or small projects related to some aspect of intuitionism (mathematics, logic or philosophy). The group will also serve those who are interested simply in acquiring a working knowledge of intuitionism per se.
Our initial studies of intuitionistic mathematics and logic will roughly follow the organization of the first chapters of my recent book Mathematical Intuitionism. However, we will refine, correct and expand the material in the book. There’ll be references and material for those who would like to pursue some topic or other even further.
The group invites both participants with some limited or even extensive background in intuitionism and those without any background in intuitionism but with an interest in learning about intuitionism and/or working on related research aims. Some knowledge of mathematics (in particular of elementary real analysis) and/or logic (in particular through basic philosophical logic) is desirable.
The group will have regularly scheduled meetings no more frequently than twice a month, during the academic year. We will set a schedule at the start of each year.
The current plan is to function for at least two or three academic years. Sometime in the second or third year we will have a conference including members and outside researchers. We will begin in late 2021 or early 2022.
From time to time will also have guest lectures from prominent researchers.
From time to time active members will prepare and present material  appropriate to their background and interests.
Anyone interested should contact me at: carl.posy@mail.huji.ac.il We will then arrange a time to speak.
    Web Site    
Find us on the web at: nylogic.github.io
(site designed, built & maintained by Victoria Gitman)
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Two events on Tuesday 9/28/21
Barcelona Set theory Seminar
ICREA Research Professor
Universitat de Barcelona
Departament de Matemàtiques i Informàtica
Gran Via de les Corts Catalanes 585
08007 Barcelona
Catalonia
Phone: +34 93 402 1609
joan.bagaria@icrea.cat
bagaria@ub.edu
Event Tuesday, September 21
Wednesday seminar
Logic Seminar Wed 15 Sept 2021 16:00 hrs at NUS by Bakhadyr Khoussainov
Logic Seminar Today 16:00 hrs SGT at NUS by Khoussainov and Stephan
Logic Seminar Today 16:00 hrs SGT at NUS by Khoussainov and Stephan
Logic Seminar 8 September 2021 16:00 hrs at NUS by Bakhadyr Khoussainov and Frank Stephan
Logic Seminar 8 September 2021 16:00 hrs at NUS by Bakhadyr Khoussainov and Frank Stephan
Logic Seminar today 16:00 hrs at NUS by Rupert Hoelzl, University of the Bundeswehr in Munich
Free Registration for IPEC 2021 until 29 August 2021 (Online Conference)
Felix Weilacher on Tuesday (8/31) 3:30 PM Eastern
Logic Seminar 1 Sept 2021 16:00 hrs at NUS by Rupert Hoelzl, Univ. of the Bundeswehr, Munich
Logic Seminar 25 April 2021 16:00 hrs by Ng Keng Meng (NTU) at NUS (today)
RIMS Set Theory Workshop: October 1215, 2021
First math logic seminar of the new semester
Logic Seminar at NUS on Wed 18 Aug 2021 at 16:00 hrs
Logic Seminar 11 Aug 2021 16:00 hrs at NUS by Frank Stephan
Events next Tuesday
Events next Tuesday
Logic seminar and set theory reading group for next week
An apology to all about today's seminar
Talk tomorrow by Gianluca Paolini at 1 30 pm (Toronto time)
Talk Friday 23rd June by Gianluca Paolini at 1 30 pm (Toronto time)
Talk in ONE hour by Richard Matthews
In this talk we shall discuss the notion of a Reinhardt embedding over several weakened base theories, primarily ZFC without Power Set, Zermelo and Power Kripke Platek. We shall see how to obtain some upper bounds, lower bounds and equiconsistency results in terms of the usual ZFC large cardinal hierarchy as well as many unexpected characteristics such embeddings can have. Moreover, we shall see that, under reasonable additional assumptions, it is possible to reobtain Kunentype inconsistency results in both ZFC without Power Set and Power Kripke Platek plus WellOrdering.
Events next Tuesday
Today at 1 30 pm talk by Richard Matthews (Toronto time)
In this talk we shall discuss the notion of a Reinhardt embedding over several weakened base theories, primarily ZFC without Power Set, Zermelo and Power Kripke Platek. We shall see how to obtain some upper bounds, lower bounds and equiconsistency results in terms of the usual ZFC large cardinal hierarchy as well as many unexpected characteristics such embeddings can have. Moreover, we shall see that, under reasonable additional assumptions, it is possible to reobtain Kunentype inconsistency results in both ZFC without Power Set and Power Kripke Platek plus WellOrdering.
Two events on Tuesday
Talk Tomorrow by Osvaldo Guzmán 1 30 pm (Totonto time)
Series finale
Talk this Friday (July 9th) by Osvaldo Guzmán 1 30 pm (Totonto time)
James Cummings series continues
Talk TODAY by Riley Thornton 1 30 pm (Toronto time)
Talk this Friday 25th (in less than two days) by Riley Thornton 1 30 pm (Toronto time)
(KGRC) research seminar talk on Thursday, June 24
Talk tomorrow 18th by David Schrittesser (1:30 pm to 3pm Toronto time)
provide a basic framework in which one can reason about optimality (or
lack thereof) of statistical methods, such as estimators and tests.
One (very weak) property of such methods is admissibility  roughly, a
method of estimation is admissible if there is no other which does
better under all circumstances (in a sense specified by the decision
theoretical framework).
Although a weak property, admissibility is notoriously hard to
characterize. Recently we have found a characterization of admissibility
(in a large class of statistical problems) in Bayesian terms, by using
prior probability distributions which can take on infinitesimal values.
(The talk will not presuppose any knowledge on statistics or nonstandard
analysis. Joint work with D. Roy and H. Duanmu.)
Talk this Friday 18th by David Schrittesser (1:30 pm to 3pm Toronto time)
provide a basic framework in which one can reason about optimality (or
lack thereof) of statistical methods, such as estimators and tests.
One (very weak) property of such methods is admissibility  roughly, a
method of estimation is admissible if there is no other which does
better under all circumstances (in a sense specified by the decision
theoretical framework).
Although a weak property, admissibility is notoriously hard to
characterize. Recently we have found a characterization of admissibility
(in a large class of statistical problems) in Bayesian terms, by using
prior probability distributions which can take on infinitesimal values.
(The talk will not presuppose any knowledge on statistics or nonstandard
analysis. Joint work with D. Roy and H. Duanmu.)
(KGRC) research seminar talk and master defense Michael Zechner
Reminder: Boise Extravaganza in Set Theory, June 1719
CMU logic events during coming week
Mathematical logic seminar: 3:30 P.M., Online, James Cummings, Carnegie Mellon University
Join Zoom Meeting: https://cmu.zoom.us/j/621951121 [cmu.zoom.us]
Meeting ID: 621 951 121
TITLE: Homological algebra for logicians
ABSTRACT: This is part 3 of a short series of talks aimed at giving some background for Nathaniel Bannister's forthcoming seminars. Nathaniel's talks will describe his work with Bergfalk and Moore on the additivity of strong homology.
I will give a rapid overview of some necessary background in homological algebra (eg abelian categories, chain complexes, derived functors). I will assume very little background, just familiarity with basic notions in category theory (category, functor, natural transformation) and algebra (the definition of an Rmodule).
TUESDAY, June 15, 2021
Set Theory Reading Group: 4:30 P.M., Online, James Cummings, Carnegie Mellon University
Join Zoom Meeting: https://cmu.zoom.us/j/621951121 [cmu.zoom.us]
Meeting ID: 621 951 121
TITLE: Homological algebra for logicians
ABSTRACT: This is part 4 of a short series of talks aimed at giving some background for Nathaniel Bannister's forthcoming seminars. Nathaniel's talks will describe his work with Bergfalk and Moore on the additivity of strong homology.
I will give a rapid overview of some necessary background in homological algebra (eg abelian categories, chain complexes, derived functors). I will assume very little background, just familiarity with basic notions in category theory (category, functor, natural transformation) and algebra (the definition of an Rmodule).
THURSDAY, June 17, 2021
Ph.D. Thesis Defense: 12:00 P.M., Online, Marcos MazariArmida
Zoom:
https://cmu.zoom.us/j/96301869290?pwd=Qk1zS0h6ZThmUnRpbmNLNkVJSjkrQT09
TITLE OF DISSERTATION: Remarks on classification theory for abstract elementary classes with applications to abelian group theory and ring theory
EXAMINERS:
Prof. Rami Grossberg (Committee Chair)
Prof. Jeremy Avigad
Prof. John Baldwin, UIC
Prof. Will Boney, Texas State
Prof. James Cummings
Barcelona Set theory Seminar
Talk tomorrow by Piotr Szewczak (1:30 pm Toronto time)
Talk this Friday June 4th by Piotr Szewczak (1:30 pm Toronto time)
Barcelona Set theory Seminar
Two events on June 8
Talk Tomorrow by Boban Velickovic at 1 30 (Toronto time)
(KGRC) research seminar talk on Thursday, May 27
An interesting series of talks for grad students
introduce some areas of set theory to the students.
them to the list of participants. vera.fischer@univie.ac.at
(it is 9:30am CET, Fridays, May 28June 18), but she will record the
talks for those who want to hear them at a later point. Here is
the program until the end of the semester.
https://sites.google.com/view/shorttalkslogicuniwien/home
