In computer science, Big Omega notation is used to describe the asymptotic upper bound of a function. It is similar to Big O notation, but it is less strict. Big O notation states that a function f(n) is O(g(n)) if there exists a constant c such that f(n) cg(n) for all n greater than some constant n0. Big Omega notation, on the other hand, states that f(n) is (g(n)) if there exists a constant c such that f(n) cg(n) for all n greater than some constant n0.
Big Omega notation is useful for describing the worst-case running time of an algorithm. For example, if an algorithm has a worst-case running time of O(n^2), then it is also (n^2). This means that there is no algorithm that can solve the problem in less than O(n^2) time.