I'm reading the following paper A Rational Account of the Perceptual Magnet Effect and I'm puzzled by equation (3) on page 2:
$$p(T|S,c) \propto p(S|T)p(T|c)$$
where $T$, $S$ and $c$ are random variables. Apparently it should be trivial, but I tried to play with conditional probability, Bayes' rule and chain rule without getting anything like this. Am I missing something very obvious?