- #1

- 2

- 0

## Homework Statement

Prove that the function $\phi(t)=t^{-1}$ is Borel measurable.

## Homework Equations

Any measurable function into $ (\mathbb{R},\mathcal{B}(\mathbb{R}))$, where $ \mathcal{B}(\mathbb{R})$ is the Borel sigma algebra of the real numbers $ \mathbb{R}$, is called a Borel measurable function

## The Attempt at a Solution

I think I need to prove that t^{-1} is a Borel set, and so prove that it is open? I am quite unclear on the actual definition of a borel measurable function, and that is perhaps my problem.