f(n,m,...) = O(g(n,m,...))
means that there exists a constant "c", for which
c * g(n,m,...) >= f(n,m,...)
is true for large enough n,m,...
####
f(n,m,...) = Ω(g(n,m,...)
means that there is ....
c * g(n,m,...) <= f(n,m,...)
####
f(n,m,...) = Θ(g(n,m,...))
means that
f(n,m,...) = O( g(n,m,...) )
and
f(n,m,...) = Ω( g(n,m,...) )