the plummeting does not occur if the nonexemptness occurs.
sent1: if the PM happens the courtesy happens. sent2: that both the courtesy and the nonexemptness occurs leads to that the plummeting does not occur. sent3: the plummeting occurs. sent4: the PM or the unbreakableness or both happens. sent5: that the courtesy does not occur is prevented by that the unbreakableness occurs.
sent4 & sent1 & sent5 -> int1: the courtesy occurs.; void -> assump1: Let's assume that the nonexemptness happens.; int1 & assump1 -> int2: the courtesy and the nonexemptness occurs.; sent2 & int2 -> int3: the plummeting does not occur.; [assump1] & int3 -> hypothesis;
$hypothesis$ = the plummeting does not occur if the nonexemptness occurs. ; $context$ = sent1: if the PM happens the courtesy happens. sent2: that both the courtesy and the nonexemptness occurs leads to that the plummeting does not occur. sent3: the plummeting occurs. sent4: the PM or the unbreakableness or both happens. sent5: that the courtesy does not occur is prevented by that the unbreakableness occurs. ; $proof$ = 
sent4 & sent1 & sent5 -> int1: the courtesy occurs.; void -> assump1: Let's assume that the nonexemptness happens.; int1 & assump1 -> int2: the courtesy and the nonexemptness occurs.; sent2 & int2 -> int3: the plummeting does not occur.; [assump1] & int3 -> hypothesis; __PROVED__