TITLE: What does the symbol := mean in mathematics?
QUESTION [12 upvotes]: What does the symbol := mean in mathematics?
for example, C(continuum) := |R|

REPLY [5 votes]: It means it is a definition in most contexts.
$f(x):=x^2-\sin 2x + \pi$
means I define $f(x)$ by the expression on the other side.
However, in most contexts, it is a superfluous notation as you argue around it.