Is there anyone doing Deep Learning research who acknowledges that it is an optimization subfield and accordingly uses rigorous math? I don't mean to be snarky

Is there anyone doing Deep Learning research who acknowledges that it is an optimization subfield and accordingly uses rigorous math? I don't mean to be snarky, and I am sure there is some use for this result, but I hope somebody is working on the math and I want to know who that person is.