# Math Help - Toplogy Question help

1. ## Toplogy Question help

Let T consist of $\emptyset$, $\Re$ and all intervals (- $\infty$,p) for p $\in$ $\Re$. Prove that T is a topology on $\Re$

2. Originally Posted by flaming
Let T consist of $\emptyset$, $\Re$ and all intervals (- $\infty$,p) for p $\in$ $\Re$. Prove that T is a topology on $\Re$
Do you know what it means to say that a collection of subsets of a set is a topology on that set?
If so, then which of the parts of that definition gives you trouble?

3. Axioms of a topology :

$\emptyset$ and $\Re$ belong to the collection.
A finite intersection of sets in the collection is in the collection.
An arbitrary union of sets in the collection is in the collection.