seeing x log so often makes me tell a result b Vitali Milman and H. Koenig about ten years ago , on Leibniz rule..apart from drrivative for real differentiable functions, the other (along with combinations) solution for general functions is f going to g given by g()=f(x) log mod f(x)….

sort of non-linear derivations

Is the chain rule in the original form true if F is channel which commutes with E and EF=F?

wonderful talk

Thanks Kun. We do make use of your results to improve private capacity of bidirectional channels (2-input, 2-output channel with two users), which also translates to bounds for class of MDI-QKD setup.

Do you have kind of Leibniz rule?