Bava Batra 158: Collapsing Case Studies

New mishnayot! A case of a house that collapsed on a husband and wife -- apparently, a second marriage, as the heirs of each deliberate which of the two died first. But there's no way to be certain which died first. Beit Shammai and Beit Hillel dispute how to divide their property. Also, a new mishnah: A case of a house that collapsed on a son and a mother -- Beit Shammai and Beit Hillel agree that the estate should be divided (presuming that he's an only son and she's a widow). Plus, the extra value of learning in the Land of Israel.