it for me and also more grounds come up in an unexpected way and the construction of so-called pseudo-random generators so these come up when you have a randomized algorithm arete the album which tosses coins and you can argue that you can mathematically prove that okay if you have uniform independent random coins then this algorithm is going to work well maybe maybe you know you can't rely on independent random coins well lower bounds can actually be used to remove the randomness from algorithms replace randomized armed systematically with