thank you so much for your emails it is extremely enjoyable to read and helps my havana as well
to explain the stira in the gemara between borer veochel and lo yibrar there were many answers and questions on each except for the last one (abaye)why cant we ask rav chisda's question on abaye as well?
(someone mentioned to me a ramban but I couldn't find it)
Rav Chisda asked the Kashya on Ula's concession to select for later in the day. And indeed, what is the difference between cooking for later in the day and selecting later in the day.
Abaye, on the other hand, is talking about selecting for what is he about to eat. The Chidushei ha'Ran explains, this is permitted because it is the beginning of the eating process, and is not considered a Melachah.
The Ramban does indeed give the identical answer - but to a different Kashya. He says that to explain how Rav Chisda can answer that it is permitted to select less than the Shi'ur, after having just refuted Ula's answer of selecting for later with 've'Chi Mutar Le'efos le'Bo ba'Yom'. See Tosfos DH 've'Chi Mutar' ('the Metaretz' is Rav Chisda).