gentzen

Or Introduction

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.

Tutorial 5. Valid arguments, searching for a proof.

Under construction 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.

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.

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

Quiz 2.

8/10/26

Consistent

Invalid

5/15/12

Propositional Main Connective

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8/10/26

Skills to be acquired in this tutorial:

To learn how to symbolize arguments, and how to judge whether they might be invalid using truth-table methods.

Why this is useful:

We wish to appraise arguments, to do this we have to symbolize them first. Judging the invalidity of arguments by truth-table methods is not particularly important, but it does help to develop skills involving truth and lists of formulas.

8/29/06

Tutorial 3 The Main Connective Applet

1/24/06

eg Lander or Suber

The problem or issue here lies with the truth table for the conditional (or material implication) ⊃