# World Logic Day Lectures 2021

UNESCO has announced that January 14 will be celebrated as World Logic Day.

Here you can see the details of the celebrations happening all around the world.

To celebrate this occasion, Association for Logic in India (ALI) (in co-ordination with Mathematics Teachers’ Association, India and Calcutta Logic Circle) is pleased to announce the following lectures.

*Time:* 7:30 pm-8:30 pm (Beijing Time)

*Speaker:* **R. Ramanujam** (Institute of Mathematical Sciences, Chennai)

*Title:* **Logic for school mathematics**

*Abstract:* All through school, students learn deductive procedures in equational theories

and employ deliberate means of reasoning in algebra and geometry. Yet, the question of whether these procedures are *reliable* never comes up in the curriculum, though there is an excellent answer: Tarski’s theorem on the decidabllity of real arithmetic. Formal propositional logic is introduced at school, but when seen in company with topics like the differential calculus, is treated rather dismissively,

Logic is not only about deductive reasoning, it is also a conscious use of formal language, understanding truth relative to models, figuring out consequence, relating assertions to algorithms that check those assertions, and studying limits to reasoning. Viewed thus, logic can serve a range of pedagogic purposes in school mathematics.

**Lecture 2**

*Time:* 9:00 pm-10:30 pm (Beijing Time)

*Speaker:* **Sourav Tarafder** (St. Xavier’s College, Kolkata)

*Title:* **Models of non-classical set theories**

*Abstract:* In this presentation, we shall discuss algebra-valued models of set theories. Different classes of algebras will be introduced which produce non-classical algebra-valued models of ZF, ZFC, a proper fragment of ZF, and finally a new version of ZF axiom system, which is classically equivalent to ZF. The validity of the mathematical statements like the Axiom of Choice, the generalized continuum hypothesis, Cantor’s theorem, Schröder-Bernstein theorem depend on their validity in the ground model. Though the models are non-classical,the foundations of cardinal numbers including the cardinal arithmetic in these models are similar to those in classical set theory. Finally we shall discuss few independence results in these non-classical set theories.

**Zoom meeting details**:

https://us02web.zoom.us/j/85603833873?pwd=RzZHWHJwa01kbDcrVFVwUTZ2QXpDZz09

Meeting ID: 856 0383 3873

Passcode: 559120

**Contact: **Md. Aquil Khan, IIT Indore (aquilk@iiti.ac.in)