In the "tall cache assumption" what does $\Omega$ represent? Within the field of cache-oblivious algorithms the ideal cache model is used for determining the cache complexity of an algorithm.  One of the assumptions of the ideal cache model is that it models a "tall cache".  This is given by the statement $Z = \Omega(L^2)$.  Where $Z$ is the size of the cache and $L$ is the size of the cache line.  What does $\Omega$ represent?
It's the lower bound counterpart to O($\cdot$). Z is larger than some constant times $L^2$