Dear Cheerful Logicians and Friends of Logic,
Supergroup announcement time! Brief Summary: There are two talks to announce, both on Thursday. First is Alejandra Diaz-Caro talking about Extensional Proofs. Second is the supergroup talk, featuring Sophia Knight, who will talk about strategy logic. Details follow. Supergroup Talk: Speaker: Sophia Knight Title: Some work on strategy logic with imperfect information Time and Date: Thursday, July 23, 8 pm GMT-5 Link: <https://ksu.zoom.us/j/7613620942> https://unimelb.zoom.us/j/846890369?pwd=TktZYmlIUGlYOU9ZaXFJcCt0TFJFZz09 Abstract: There is a great deal of work on logics for games in multi-agent systems. These logics are concerned with formally defining statements like "If Alice and Bob cooperate, they can follow a strategy so that they are certain to achieve their goal," or "no matter what Cath does, she cannot be sure of achieving her goal," or "Alice can ensure that either Bob is certain not to reach his goal, no matter what he does, or Cath is cerain to reach her goal if she follows the right strategy." My talk will be focused on how to include imperfect information in these systems: if the agents do not have full information about the current state of the system, how does this change their power to act strategically in order to achieve their goals? In particular, I will discuss my current work with Bastien Maubert on some approaches to the formal expression of agents' knowledge and strategic abilities in multi-agent systems with imperfect information. I will begin by presenting Alternating-time Temporal Logic (ATL), a logic describing the abilities of coalitions of agents in concurrent game structures. I will describe some difficulties with adapting variants of ATL to imperfect information settings. Next I will introduce Strategy Logic (SL), a logic with a similar purpose to ATL, which differs in that it takes strategies to be explicit objects in the logic, making it more powerful but less decidable than ATL. For example, SL can state the existence of Nash equilibria, whereas ATL cannot. I will describe our current work on an imperfect information variant of SL, the addition of epistemic operators, the difficulties in restricting SL to only consider uniform strategies, and a solution to this difficulty. Talks by Member Groups: Lógicos em Quarentena (SBL) Speaker: Alejandro Diaz-Caro Title: Extensional proofs in a propositional logic modulo isomorphisms Time and Date: Thursday, July 23, 4pm GMT-3 Link: https://meet.google.com/keg-nezd-dnz Abstract: Joint work with Gilles Dowek. System I is a proof language for a fragment of propositional logic where isomorphic propositions, such as A∧B and B∧A, or A⇒(B∧C) and (A⇒B)∧(A⇒C) are made equal. System I enjoys the strong normalization property. This is sufficient to prove the existence of empty types, but not to prove the introduction property (every normal closed term is an introduction). Moreover, a severe restriction had to be made on the types of the variables in order to obtain the existence of empty types. We show here that adding η-expansion rules to System I permit to drop this restriction and to retrieve full introduction property. Preprint at arXiv.org:2002.03762. Other Notes and Announcements: - *The Logic Supergroup has a YouTube channel!* Recordings of almost all talks are available at https://www.youtube.com/channel/UCqOAS8SHP-5nGjYEE2FE6xw - To access the supergroup calendar, please follow this link: https://calendar.google.com/calendar?cid=ZGhoanNoanF1bGhmaG9xam5scDJlc2o0bDhAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ - To access the member groups joint calendar, please follow this link: https://calendar.google.com/calendar?cid=aG8wNWljaGxkNXI2N2oyMnZvY3BzdmRoMWNAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ - 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. Yay for logic! -- 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/CAMTR990Zfs%3DX4vLdwGscz%2Bdh6ToFanRDZWttwKg69w0aeMmSvg%40mail.gmail.com.
