# identity

## Tutorial 3 Identity: Uniqueness, Definite Descriptions, Iota

Topic

Logical System

## Tutorial 2 Identity: Functional Terms and Rules of Inference

Topic

Logical System

## Deriver [Functional Terms, Identity, First Order Theories, Set Theory—Gentzen Syntax]

Logical System

###### 12/26/13

Welcome!

The tutorials presented here look at some topics in logic to the level of intermediate to advanced Predicate Calculus. They build on the Tutorials of Easy Deriver which provided the introductory material to Propositional and Predicate Calculus.

The program, widgets, or Notes, should be accompanied by a suitable textbook, such as:

## Tree Tutorial 5: Identity Rules

Logical System

2013

### Skills to be acquired in this tutorial:

To become familiar with the new rules for predicate logic trees with identity.

### Reading

Colin Howson, [1997] *Logic with trees* Chapter 9

### Tutorial:

It is possible to use trees with formulas containing identity. Really there are two different ways to implement it: either there are two new rules, or there is one new rule and a new way of closing a branch from a single formula. Both will be described.