Dear Cheerful Logicians and Friends of Logic, It's another big week! Nine events. Woohoo! I won't summarize them here, so just skip on down to the good stuff below. Hooray for logic!
*Supergroup Talk:* *Speaker: *Michaela McSweeney *Title: *Logical Realism, Anti-Exceptionalism, and the Cost of Closure *Time and Date:* Thursday, April 22, 20:00 GMT-5 *Link*: https://unimelb.zoom.us/j/88904597769?pwd=Zi9LOUlDVHBqWTV0b0RsVGRwVko0QT09 *Passcode*: 176963 *Abstract: *Philosophers of science often assume that logically equivalent theories are in fact theoretically equivalent; in fact, this is an implicit commitment in most accounts of theoretical equivalence. I argue that (a) one version of anti-exceptionalism about logic raises a serious epistemic worry for this commitment, and that (b) logical realism (which says, roughly, that differences in logic reflect genuine metaphysical differences in the world) raises a serious metaphysical worry for it. It might be thought that we can contain these problems--or at least those raised by logical realism--by treating theoretical equivalence as domain-specific: theoretical equivalence, on this view, does not entail metaphysical equivalence, since metaphysics makes more fine-grained distinctions between theories than science does. I do not think this move works. Talks by Member Groups: *Logic and Metaphysics Seminar (CUNY)* *Speaker: *V. Alexis Peluce *Title: *Brouwer's First Act of Intuitionism *Time and Date: *Monday, April 19, 15:15 GMT-5 *Link: * https://gc-cuny-edu.zoom.us/j/88000847766?pwd=d29KdlZxQlp0a1Y5dlBEVldtbGMrQT09 *Meeting ID*: 880 0084 7766 *Passcode*: 269353 *Abstract: *L.E.J. Brouwer famously argued that mathematics was completely separated from formal language. His explanation for why this is so leaves room for interpretation. Indeed, one might ask: what sort of philosophical background is required to make sense of the strong anti-linguistic views of Brouwer? In this talk, we outline some possible answers to the above. We then present an interpretation that we argue best makes sense of Brouwer’s first act. *Alophis Seminar (Cagliari)* *Speaker: *Alessandra Palmigiano *Title: *From Unified Correspondence to Parametric Correspondence: Preliminary Considerations *Time and Date: *Tuesday, April 20, 8:00 GMT-5 *Link*: https://us02web.zoom.us/j/89674891691?pwd=WUlibU9GZHRNcXlWdkdzQTFLSnFtQT09 *Meeting ID*: 896 7489 1691 *Passcode:* 157537 *PHILMATH-EXPRESS seminar* *Speaker: *Rosalie Iemhoff *Title: *Proof-Theoretic Formalization *Time and Date: *Tuesday, April 20, 9:00 GMT-5 *Link: * https://uva-live.zoom.us/j/84932098608?pwd=SVd2Z3NiajgyRytvRzJza29MU0krQT09 *Meeting ID*: 849 3209 8608 *Passcode*: 485223 *Helsinki Logic Seminar* *Speaker: *John Lång *Title: *The model D∞ *Time and Date: *Wednesday, April 21, 4:00 GMT-5 *Link: * https://helsinki.zoom.us/j/62891400777?pwd=UldCeThTaTJVQjUzUFo4S2ErcndNQT09 *Abstract: *Lambda-terms in pure untyped lambda-calculus are often characterised as anonymous functions. Formalising this simple description is less trivial than it seems. As a general term formation rule, juxtaposing any two lambda-terms yields a new lambda-term called an application. If the left-hand side term can be interpreted as a function f and the right-hand side term can be interpreted as an element x in the domain of f, then the application can be interpreted as the value f(x). This naïve interpretation breaks down when a lambda term is applied to itself. On one hand, self-application enables unrestricted recursion, making lambda-calculus Turing-complete. On the other hand, combining self-application and logical connectives may also lead into paradoxes and contradictions. In the late 1960'ies, Dana Scott found a way to represent pure untyped lambda-calculus in set theory in a logically sound way in what he calls the first "mathematical" model of lambda-calculus, the model D∞. This model is a combination of order theory, topology, and categorical thinking that started the fields of denotational semantics and domain theory. *Proof Theory Seminar* *Speaker: *Greg Restall *Title: *Comparing Rules for Identity in Sequent Systems and Natural Deduction *Time and Date: *Wednesday, April 21, 4:00 GMT-5 *Link: *see https://www.proofsociety.org/proof-theory-seminar/participate.html <https://www.proofsociety.org/proof-theory-seminar/participate.html> *Abstract:* It is straightforward to treat the identity predicate in models for first order predicate logic. Truth conditions for identity formulas are straightforward. On the other hand, finding appropriate rules for identity in a sequent system or in natural deduction leaves many questions open. Identity could be treated with introduction and elimination rules in natural deduction, or left and right rules, in a sequent calculus, as is standard for familiar logical concepts. On the other hand, since identity is a predicate and identity formulas are atomic, it is possible to treat identity by way of axiomatic sequents, rather than inference rules. In this talk, I will describe this phenomenon, and explore the relationships between different formulations of rules for the identity predicate, and attempt to account for some of the distinctive virtues of each different formulation. *Indiana University Logic Seminar* *Speaker: *Anthia Solaki *Title: *Bounded multi-agent reasoning: inference, introspection, attribution *Time and Date: *Wednesday, April 21 15:00 GMT-5 *Link: * https://iu.zoom.us/j/95326399432?pwd=VmVUWGxHeG5KQjEzQVozb3pCRHJVZz09 *Meeting ID*: 953 2639 9432 *Password*: Smullyan *Abstract*: Epistemic logic, seen as a spin-off of normal modal logics, is often challenged on basis of its adequacy to model actual human reasoning, especially in light of empirical evidence on people's performance in reasoning tasks. It models agents as unlimited reasoners, who perform deductive inferences, introspect, and reason about others' reasoning, despite bounds of memory or time. We propose a logic for reasoning in a multi-agent setting, that is properly informed by empirically indicated bounds. We introduce (i) a resource-sensitive impossible worlds semantics, to account for the fallibility of real reasoners, and (ii) dynamic operators and model updates, inspired by Dynamic Epistemic Logic (DEL), to represent actions that, when affordable, can refine the zero- or higher- order epistemic state of agents. Furthermore, we illustrate a technical connection between this attempt and syntactic approaches against the problem of logical omniscience and its benefits towards obtaining a sound and complete axiomatization. Finally, we explain why this line of work makes for a suitable basis for the incorporation of more cognitive parameters into a logical model. *Milano Logic Lunch Seminar* *Speaker: *Ariana Novaro *Title: *Unravelling multi-agent ranked delegations *Time and Date: *Thursday, April 22, 5:30 GMT-5 *Link: *https://zoom.us/j/94655925446?pwd=VDM3QzF0OEgxdEQ2YWpXa3I0VWZkdz09 *Meeting ID*: 946 5592 5446 *Passcode*: 28ZGuu *Abstract: *In this talk, I will present a framework for collective decision-making where the agents have to vote on a given issue, but they can also choose to delegate their vote (if, for instance, they did not have the time or expertise to take a stance on the issue at stake). The agents can express complex delegations, i.e., they can specify a set of trusted delegates and a function--being it a classical voting rule or a propositional formula--to decide their vote, and they can also provide a ranking of preferred delegations. Given these complex delegation ballots, I will present four algorithms that unravel the ballots to get a profile of direct votes, on which the final decision can be taken by using some standard voting rule. In particular, I will discuss both the algorithmic properties and the computational complexity of the four algorithms, for different restrictions on the language of the delegation ballots. This is joint work with Rachael Colley and Umberto Grandi. *UConn Logic Group* *Speaker: *Ulf Hlobil *Title: *Bilateralist Truth-Maker Semantics for ST, TS, LP, K3, … *Time and Date: *Friday, April 23, 9:00 GMT-5 Link: https://us02web.zoom.us/j/84526659736?pwd=c2tjRTVlWnc5bnp0U2htR3Jra0FjZz09 *Meeting ID*: 845 2665 9736 *Passcode*: 753658 *Abstract: *The talk advocates a marriage of inferentialist bilateralism and truth-maker bilateralism. Inferentialist bilateralists like Restall and Ripley say that a collection of sentences, Y, follows from a collection of sentences, X, iff it is incoherent (or out-of-bounds) to assert all the sentences in X and, at the same time, deny all the sentences in Y. In Fine’s truth-maker theory, we have a partially ordered set of states that exactly verify and falsify sentences, and some of these states are impossible. We can think of making-true as the worldly analogue of asserting, of making-false as the worldly analogue of denying, and of impossibility as the worldly analogue of incoherence. This suggests that we may say that, in truth-maker theory, a collection of sentences, Y, follows (logically) from a collection of sentences, X, iff (in all models) any fusion of exact verifiers of the members of X and exact falsifiers of the member of Y is impossible. Under routine assumptions about truth-making, this yields classical logic. Relaxing one such assumption yields the non-transitive logic ST. Relaxing another assumption yields the non-reflexive logic TS. We can use known facts about the relation between ST, LP, and K3, to provide an interpretation of LP as the logic of falsifiers and K3 as the logic of verifiers. The resulting semantics for ST is more flexible than its usual three-valued semantics because it allows us, e.g., to reject monotonicity. We can also recover fine-grained logics, like Correia’s logic of factual equivalence. Other Notes and Announcements: - To access the supergroup calendar, please follow this link: https://calendar.google.com/calendar?cid=ZGhoanNoanF1bGhmaG9xam5scDJlc2o0bDhAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ <https://protect-au.mimecast.com/s/hA6yCyoNK5UrmELwZSRhi4A?domain=calendar.google.com> - To access the member groups joint calendar, please follow this link: https://calendar.google.com/calendar?cid=aG8wNWljaGxkNXI2N2oyMnZvY3BzdmRoMWNAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ <https://protect-au.mimecast.com/s/4AJkCzvOL5hMNv4Z6HoM9dI?domain=calendar.google.com> - If you represent a member group and would like your events to appear on the joint calendar, be sure to add them! Contact any of the organizers if you need permission to do so. - To view the videos of past talks on our YouTube page, please follow this link: https://www.youtube.com/channel/UCqOAS8SHP-5nGjYEE2FE6xw <https://protect-au.mimecast.com/s/v440COMxAksprgoGksr3AwV?domain=calendar.google.com> -- Você está recebendo esta mensagem porque se inscreveu no grupo "LOGICA-L" dos Grupos do Google. Para cancelar inscrição nesse grupo e parar de receber e-mails dele, envie um e-mail para [email protected]. Para ver esta discussão na web, acesse https://groups.google.com/a/dimap.ufrn.br/d/msgid/logica-l/CABs6tO%3DsR8RWizKpiY4EZ-szB8ruT_dOj3Jx%3DtNGH9r6GGoN2w%40mail.gmail.com.
