Of all the amora’im, Abaye and Rava are presented as epitomizing the discussions that take place in the Gemara. In all of their arguments in the Gemara, the halakha always follows Rava’s opinion, with only six exceptions. Those six are referred to by the Gemara by the acronym YAL KGM:
Yeush shelo mida’at (our daf today) – When a person does not realize that he has lost an object until after it is picked up by someone else, and he gives up ownership when he realizes it, can we apply it retroactively? Abaye rules that despair that is not conscious is not despair, and despair is needed for the ownership to transfer.
Lehi ha-omed me-elav (Massekhet Eiruvin 15a) – When a pole is standing on its own (it was not placed there by a person), can it be used as part of the structure that will create a legal private domain on Shabbat for the purpose of carrying?
Gilui da’at be-giṭṭin (Massekhet Gittin 34a) – If a person makes a statement that can be understood as affecting the divorce that has been sent to his wife, must we take it into consideration when ruling on the validity of the divorce?
Mumar la’avor aveira le-hakh’is (Massekhet Sanhedrin 27a) – Can an apostate be trusted to testify in court?
The disagreements between Abaye and Rava are among the most important in the Gemara, to the extent that deep, significant Talmudic discussions are called havayot d’Abaye ve-Rava. Although it is difficult to discern two clear distinctive approaches, generally speaking we find that Abaye was more formalistic, while Rava is more open and his opinions are based more on logical thinking.