Bava Metzia 100: Oath-taking to Establish a Sale (except for slaves)

The laws of transactions between buyers and sellers, in parallel to borrowers and lenders. With the example of a pregnant cow that was traded for a donkey... What happens when the parties take opposite positions with differing levels of certainty? Also, the Gemara delves into slaves in the slave market, worth different values - and a buyer and seller who disagree over which slave had been purchased. Plus, a new mishnah on selling olive trees, which then bear fruit. Whose olives are they?