Bava Batra 6 - July 1, 25 Sivan

Can one use a ma li l'shaker claim against a chazaka, as in the case where a creditor demands payment after the date of the loan was already due and the borrower claims that they returned a loan before loan's due date? Do we believe the borrower since a better claim could have been made (that he/she paid back the loan on time) or is this not accepted since there is a chazaka, assumption that people do not repay loans before the due date? Three tannaitic sources are brought, two of them from our Mishna, to try to answer the question, but all attempts are rejected. If a dividing wall in a courtyard between two neighbors fell and one only wanted to rebuild to a height of four cubits and the other wanted it higher, one cannot force the other to share in the cost of the higher part of the wall. But if the neighbor who did not want to pay for the higher wall built a wall in their courtyard opposite the other at a higher height, indicating they want to connect the walls with a ceiling, they need to share the original wall's cost. If the wall they built is shorter than the dividing wall (but above four cubits) or its length is shorter and only some of it is opposite the other wall, do they need to share the cost of the entire wall or only the part they will use? Rav Huna and Rav Nachman have different opinions on this issue. Although, there are particular cases where each side agrees with the other's position. Rav Nachman and Rav Yosef also discuss different situations where one can assume or not assume that a neighbor agreed to permit usage of their wall to their neighbor. For example, if one permitted one's neighbor to rest small beams on their wall (did not protest when the neighbor did that), does that mean they also would permit larger beams? If one rents a room in a large house, what other parts of the house can the renter use besides the room? If two neighbors live opposite each other, each is required to build a fence for the length of half their roof (each builds it on the half opposite the exposed half of the neighbor) to block the ability of each one to see into the other's roof. Why is there a concern for neighbors looking in and not for people in the public domain looking in? What are the laws when a roof and a courtyard are at the same level opposite each other?