I need to know how to read the notation on page three of this article: http://fitelson.org/few/few_05/egan.pdf

I know almost nothing about how to read the notation I’m looking at. The sigma has something to do with… summing something up, I think. Is that the ‘v’ of disjunction or something else? I know the probability notation in the first parentheses–but is the second parentheses enclosing a product (of H and A) or does juxtaposition not mean products here? If a product, how do you compute the product of a set of worlds and an action? Where did that random ‘c’ come from?

Thanks for any pointers…