# propositional

## Tutorial 9: The Remaining Sentential Rules of Inference

Topic
Logical System

2013

### Skills to be acquired:

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

Bergmann[2008] The Logic Book Section 5.1 and 5.4

### The Tutorial:

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

## Tutorial 8: Reductio ad Absurdum

Topic
Logical System

2013

### 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).

Bergmann[2004] The Logic Book Section 5.1 and 5.4

### The Tutorial:

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

## Help with Conditional Proof

Topic
Logical System

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.

Your browser does not support html5 video.

## Tutorial 7: Conditional Proof

Topic
Logical System

2013

### Skills to be acquired:

Learning conditional proof.

Bergmann[2008] The Logic Book Section 5.1 and 5.4

### The Tutorial:

The five remaining sentential rules of inference are slightly more difficult than the ones that we have met before. They are slightly more difficult in that they require you to make new assumptions, and the correct new assumptions at that. However they follow a similar pattern to each other so mastery of one should lead to mastery of the others.

Topic
Logical System

Topic
Logical System

## Help for Tutorial 5

2013

### Tutorial 5 Example: Doing a derivation

This movie shows the downloadable application being used, but the manipulations are so similar to those of the web page applet that it really covers both.

Your browser does not support html5 video.

Topic
Logical System

## Tutorial 5. Valid arguments, searching for a proof.

2013

### Skills to be acquired in this tutorial:

Proving an argument to be valid by displaying a derivation. Simple propositional derivations using some of the Rules of Inference.

Bergmann[2004] The Logic Book Section 5.1.

### The Tutorial:

If you suspect that an symbolized argument might be valid, you should attempt to give a derivation of it.

A derivation is a proof of validity.

Topic
Logical System

## Review of material presented thus far

Review of new material

There are the truth-tables for the connectives...

Negation

 F ∼F True False False True

Conjunction

Topic
Logical System

1/7/13

Topic
Logical System