My name is Włodzimierz Holsztyński. Here, at MATHEMATICS (stackexchange), my id is Wlod AA. I have this id on MathOverflow too, as well as Włodzimierz Holsztyński. However, I've decided to have nothing to do with MathOverflow anymore, some months ago (it's 2017-12-17 right now, when I am writing these words).