 Let the belief set \(K\) include both a belief that the coin was tossed \((c)\) and a belief that it landed heads \((h)\). The epistemic agent wishes to consider whether, on the supposition that the coin had been tossed, it would have landed heads. In order to do that, it would seem reasonable to remove \(c\) from the belief set and then reinsert it, i.e. to perform the series of operations \(K\div c+c\).