Question: What would R. Meir say about declaring Hefker for a limited period of time?

Suggestion: If a person declared his field Hefker for two or three days, he may retract. (For three days, M'DeRabbanan it is not considered Hefker since he can retract; but for more than three days, he cannot retract and it is Hefker.)

(R. Shimon the Judge taught before R. Zeira): He may retract even after three days.

(R. Zeira): If you say that there is no difference between three or more than three days, in any case of a limited Hefker he can always retract.

Support (Baraisa): When does it become Hefker? When he made it permanently Hefker, but if he said, "My field is Hefker for one day'', "for one week'', "for one month'' or "for one Shemittah cycle'' - if nobody has acquired it yet, he may retract.

Conclusion of proof: This shows that even if declared Hefker for a limited time, it is valid. This also shows that they were not concerned for deception (even though since it had been Hefker, if he acquires it again, it is now exempt from Maaseros). This also shows that a person may declare something Hefker and then acquire it again.

This supports R. Zeira's answer (above (d)) that there is no difference between an extended period of time of Hefker and a shorter period of time - they are both called a limited Hefker.

Question: (The Mishnah said (above Zevachim daf 55 (b)) that if all of the sheaves of a field were a Kav and one was four Kav and he forgot it, Beis Shammai say that it is not Shichechah and Beis Hillel say that it is Shichechah.) What is the reasoning of Beis Shammai? If it is because this sheaf is much larger and significant, two Kav should be enough; if it is because it is considered its own row, three should be enough?

Answer (One Rabbi before Reish Lakish in R. Yochanan's name): According to Beis Shammai, a row consists of four sheaves.

Question (R. Yona): Do we say that just as when each sheaf is one Kav and one is four Kav, Beis Shammai says that it is not Shichechah, so too if each sheaf is two Kav and one is eight Kav? (This question remains unanswered.)