 If (2) is contingent, then there is a possible history where the battle occurs the day after the time of evaluation, and another one where it does not occur then. So to evaluate (2) you need to know two things: what is the time t of evaluation, and which of the histories h that run through t is the one to be considered. So a sentence in such a logic is evaluated at a pair \(\langle t, h\rangle\).