# Constructing Mathematical Statements

1. Mar 4, 2008

### danago

Hi. Ive just started a new maths course and i have come to realise that i have never been taught how to use symbols to write mathematical statements. For example, up until a day ago, i didnt know what $$\exists$$ or $$\forall$$ meant.

Is anybody able to share some links that will explain the use of such symbols to construct statements? I am able to construct really basic statements such as:

"For all x>4 there exists x>5" $$\forall x>4 , \exists x>5$$

But i dont even know if what i have written above is correct, or how to write more complex statements.

Dan.

2. Mar 4, 2008

### mrandersdk

you could take a look at

http://en.wikipedia.org/wiki/First-order_logic

maybe it is a bit too general to really helpfull, look especialy at the sections: Provable identities and Provable inference rules, they are very important.

Since you haven't seen these before i guess they are theaching them to you in the class, and the best way to learn it is really just to use them alot. Else try to find some basic analysis books they should teach it. I can't say a specific book because the book i learned it from was in danish so it will probaly don't help much.