Mathematics, Machine Learning, Reinforcement Learning, Optimization.
https://web.stanford.edu/~boyd/cvxbook/bv_cvxbook.pdf https://ai.googleblog.com/2020/07/duality-new-approach-to-reinforcement.html http://www.onmyphd.com/?p=duality.theory https://www.stat.cmu.edu/~ryantibs/convexopt-F16/scribes/kkt-scribed.pdf https://arxiv.org/pdf/1705.10528.pdf