I'm undergraduate student in probability theory (and its applications). There are lots of different and definitely good text on standard, functional analysis-based approach, but I'm interested in alternative approaches - maybe, some more algebraic variants. Could you name some ideas/papers/texts about this? I'm especially interested in the ones those can be used in applied problems (such as financial mathematics or something). I've surely saw some approaches in Wikipedia, but I have absolutely no idea of using them in practical problems.