The first equation on page 8 of the arXiv paper http://arxiv.org/abs/1503.01472 seems strange to me. It looks like saying "function F(t) given by F(t) + Sum(something)." Shouldn't it use ':=' symbol instead of '+', like "F(t) := Sum(something)"? Or maybe this is the case when math notation is so complex that common symbols have completely different meaning?