propositional

8/12/26

Skills to be acquired:

Learning the Rules Or Elimination and the Introduction of the Biconditional.

The Tutorial:

Or Elimination, in the guise of Dilemma, also is a form of inference dating from antiquity.

The core idea of it that if a conclusion follows from both disjuncts of a disjunction, then the conclusion follows full stop. As an example in English, if either I am going to eat an ice-cream or I am going to eat some cake, and if I eat ice-cream I break my diet, and if I eat cake I break my diet, then ... I break my diet.

Quiz 6 Applet

This contains an applet, so it will be slow loading and likely it will ask you about security.

8/1/2/26

Skills to be acquired:

Learning reductio proof, both as plain Negation Introduction and via (double) Negation Elimination (to prove some formulas that do not have negation as their main connective).

The Tutorial:

Reductio ad Absurdum is the second of the classical forms of inference.

Quiz 5.

9/14/06 This contains an Applet, which means that it will be slow to load and your browser will ask you if you want to run it (over to you on that one).

9/12/06

Conditional Proof

This video shows the techniques for Conditional Proof using the downloadable application Deriver. But the techniques are exactly the same for the Proof applet running in a web page. So, the video may look slightly different to what you are looking at, but the underlying principles and approach are the same.