Originally Posted by

**topsquark** First a few definitions from my text in case the language is not quite universal.

1. Let X and Y be topological spaces; let $p: X \to Y$ be a surjective map. The map p is said to be a **quotient map**, provided a subset U of Y is open in Y if and only if $p^{-1}(U)$ is open in X.

2. If a set X is a (topological) space and if $p: X \to Y$ is a surjective map, then there exists exactly one topology T on Y relative to which p is a quotient map; it is called the **quotient topology** induced by p.

3. Let X be a (topological) space, and let Y be a partition of X into disjoint subsets whose union is X. Let $p: X \to Y$ be the surjective map that carries each point of X to the element of Y containing it. In the quotient topology induced by p the space Y is called a **quotient space** of X.

Now for a few questions. I am addressing the definitions "backward", which is always a bad idea.

Definition 3 is clearly referring to an equivalence relation ~ on X, which should indicate that Y is the set $\{y | y \sim x \} ~ \forall ~ x \in X$. Taking this as a given, definition 2 seems to be merely saying that there is more than one possibility of a quotient topology on Y since there is in general more than one equivalence relation from X to Y and hence more than one p which would induce different quotient spaces Y.