When you’re working on the natural deduction proofs for PS2, it might be helpful to consider rewriting a formula uses a logical equivalence. For example, there is an equivalence between p–>q and ~p v q. However, if you use something like this, you must also show a side proof that the equivalence is correct. That is, you should show that you can assume each of the sides and prove the other. If you do that, you will receive full credit for the use of that rule. However, if you use a logical equivalence that isn’t one of the specific rules given in the book without showing that it is valid, only partial credit will be given.

# Author: admin

## Notes on Modal Logic (9/13)

## Slides from 09/10

## Slides from 09/03

## Problem Set #1

## Reading: Reichenbach – The Tenses of Verbs

## Doing Proofs in Propositional Logic

## Chapter 1 Reading.

The text is available on Latte under “Files”. I’d like you to have read Chapter 1 by Tuesday September 3. I will cover proof theory for propositional logic and semantics for PL tomorrow. I will have the problem set ready for distribution tomorrow as well.

-James

## Welcome to Modal Logic!

I look forward to meeting you all this morning for our first class. I will survey the vast field of modal logic and how it is used in philosophy, linguistics, computer science, psychology, economics, and political science. The first two weeks will involve an intense treatment of proof theory for propositional and first-order logic, and their corresponding model theories, in order to get us ready for modal relation structure. We then proceed to an in-depth study of modal and dynamic logic, especially their applications to temporal and spatial systems, and how they are used in the modeling of linguistic data.

## Problem Sets

Problem sets will be posted in this section.