# Thread: What is this notation

1. ## What is this notation

After the f o g and g o f, there is a something and a v.

What is that?

2. ## Re: What is this notation

Originally Posted by dwsmith
After the f o g and g o f, there is a something and a v.

What is that?
That is an iota. Usually it indicates an \.

3. ## Re: What is this notation

Originally Posted by dwsmith
After the f o g and g o f, there is a something and a v.

What is that?

$\iota_V:V \to V, \,\,\,\iota_{V}(x) = x, \,\,\forall x \,\in V$.

4. ## Re: What is this notation

normally iota is used for an inclusion morphism. if the sub-object is the same as the target of the morphism (just as any set can be a subset of itself), then this becomes the identity map.