Bava Batra 31 - July 26, 20 Tamuz

The Gemara brings several cases that came before the courts regarding property ownership claims. In the first case, Rava ruled that the possessor's claim is believed since if the possessor was lying, he could have made a better claim (ma li l'shaker). But Abaye said this wasn't accepted as witnesses testified against the claim and a ma li l'shaker isn't accepted in this situation. After that, the possessor modified his claim. Can one modify one's claim? Ulla and the rabbis of Nehardea disagreed regarding this issue. In which cases did each side acquiesce to the other?

Rava and Rav Nachman disagreed in a case where part of the testimony was contradicted by other testimony but the other part wasn't. Is the entire claim canceled, or is the part that wasn't contradicted still valid? In that same case, new evidence was brought that contradicted the court’s ruling. Should the court reverse its decision and take the land away, or should the court stick with its original decision to prevent people from losing respect for the courts?