What do the letters stand for where the Halacha follows Abaye?
Moshe Lidberman, USA
Sholom Rav,
In answer to your question, I quote Rashi:
Yud - Yi'ush she'Lo mi'Da'as (in Eilu Metzi'os, Bava Metzi'a, 29b).
Ayin - 'Eid Zomeim' (here).
Lamed - 'Lechi ha'Omeid me'Eilav' (first Perek of Eruvin, Daf 15a).
Kuf - 'Kidushin she'Lo Nimseru le'Bi'ah' (second Perek of Kidushin, Daf 51a).
Gimel - 'Giluy Da'as be'Gitin' (Ha'Shole'ach Get, Gitin, Daf 34a).
Mem - 'Mumar Ochel Neveilos Lehach'is (later).
Kind regards,
Eliezer Chrysler