Question (Rav Yosef bar Shemayah - Beraisa #1 - R. Nechemyah and R. Eliezer ben Yakov): The produce is forbidden [to move or eat] unless it was returned to its place b'Shogeg.

Inference: If it was returned b'Mezid, it is forbidden!

Answer: Tana'im argue about this:

(Beraisa #2): If produce left the Techum b'Shogeg, one may eat it. If it left b'Mezid, one may not eat it;

R. Nechemyah says, one may eat it in its [original] place, but not outside its place.

Question: When does R. Nechemyah permit it in its place?

Suggestion: He permits even if it was returned b'Mezid.

Rejection: In Beraisa #1 he permits only if it was returned b'Shogeg!

Answer: He permits if it was returned b'Shogeg. Beraisa #2 is abbreviated. It means as follows:

If produce left the Techum b'Shogeg, one may eat it. If it left b'Mezid, one may not eat it;

This discusses eating out of its [original] place. One may eat it in its place even [if it left and was returned] b'Mezid.

R. Nechemyah says, [it is forbidden out of its place, and] even in its place it is permitted only [if it was returned] b'Shogeg, but not b'Mezid.

Rejection: No. If it was b'Mezid, all forbid [even] in its place. (The Beraisa is not abbreviated. The first Tana does not discuss if it was returned);

They argue about out of its place if it was taken b'Shogeg. The first Tana permits, and R. Nechemyah forbids, unless it was returned.

Rejection of rejection (Seifa of Beraisa #1 - R. Nechemyah and R. Eliezer): It is forbidden unless it was returned b'Shogeg.

Inference: If it was returned b'Mezid, it is forbidden. [They come to be more stringent.] This implies that the first Tana permits even Mezid!

Conclusion: Tana'im argue about Mezid.

(Rav Nachman): If one was walking and does not know where the Techum ends, he takes 2000 medium steps. (A normal step is one Amah.) This is the Techum.

(Rav Nachman citing Shmuel): If one was Shoves in a valley and Nochrim surrounded the [entire] valley with Mechitzos on Shabbos, he may walk 2000 Amos and transfer in the entire valley [even past where he may walk] through throwing.

(Rav Huna): He may walk 2000 Amos. He may transfer only in four Amos. (The Mechitzos do not permit, because they were not there at the start of Shabbos.)

Question: He should be permitted to transfer in the entire valley through throwing!

Answer: We decree to forbid, lest he be drawn after the item [and carry it past 2000 Amos].

Question: In any case, he should be permitted to transfer within 2000 Amos!

Answer: [Since he may not carry past 2000, and nothing indicates where this ends,] this is like a wall [of a Reshus] that is totally breached to an area in which people of the Reshus may not carry.

(Chiya bar Rav): He may walk 2000 Amos and carry in 2000 Amos.

Question: This is unlike Rav Nachman and unlike Rav Huna!

Correction: Rather, [he may walk 2000] and transfer only in four Amos.

Question: If so, this is just like Rav Huna!

Answer: Indeed, it should say 'and also Chiya bar Rav said...'

Rav Nachman (to Rav Huna): Do not argue with Shmuel, for a Beraisa supports him!

(Beraisa): If Reuven [was Me'arev,] and counted his steps and found that his 2000 Amos (Techum) end in the middle of a city, he may transfer in the entire city, as long as he does not walk past his Techum.

Suggestion: He throws to transfer past where he can walk!

Rejection (Rav Huna): No, he transfers by pulling [something outside his Techum, there is no concern lest he be drawn after the item. Rashi's text omits this rejection.]

(Rav Huna): If Reuven measured his 2000 Amos and they end in the middle of a Chatzer, he is permitted [to carry] in only half the Chatzer.

Objection: This is obvious!

Correction: Rather, [the Chidush is not that the other half is forbidden, rather, that] half the Chatzer is permitted to him.

Objection: Also this is obvious!

Answer: One might have thought that we decree lest he carry in the entire Chatzer. Rav Huna teaches that this is not so.

(Rav Nachman): Rav Huna agrees that if his 2000 Amos end at the edge of a roof (the wall underneath was breached; even though he may not enter the house), he may transfer [through throwing] in the entire house.

Question: What is the reason?

Answer: It is as if the [edge of] the roof descends [and makes a Mechitzah at the end of his Techum, therefore we are not concerned lest he enter the house].

(Rav Huna brei d'Rav Noson): Tana'im argue about whether or not we forbid transferring due to walking:

(Mishnah - R. Gamliel and R. Elazar ben Azaryah): If they brought him to another city and put him in a Dir or Sahar, all of it is permitted to him;

R. Yehoshua and R. Akiva say, he has only four Amos.

Suggestion: R. Gamliel and R. Elazar do not decree to forbid walking in a Dir or Sahar due to walking in a valley. Similarly, they do not forbid transferring due to walking. R. Yehoshua and R. Akiva forbid walking past four Amos in a Dir or Sahar due to walking in a valley. Similarly, they forbid transferring due to walking!

Rejection #1: R. Gamliel and R. Elazar do not forbid in a Dir or Sahar due to a valley because they are very different. (A Dir or Sahar has Mechitzos, but a valley does not.) Perhaps they forbid transferring due to walking in the same Reshus, lest he be drawn after the object!

Rejection #2: Perhaps R. Yehoshua and R. Akiva do not decree. Rather, they consider the entire house (or a Dir) like four Amos only when he was Shoves within Mechitzos!

(Rav): The Halachah follows R. Gamliel regarding a Dir, Sahar or boat.

(Shmuel): The Halachah follows R. Gamliel regarding a boat, but not regarding a Dir or Sahar.

Question: All agree that the Halachah follows him regarding a boat. What is the reason?

Answer #1 (Rabah): It is because he was Shoves within Mechitzos from before Shabbos;

Answer #2 (R. Zeira): It is because the boat constantly moves him out of his four Amos. (He is like one who was forcibly taken by Nochrim out of his four Amos. He receives the four Amos in which they put him. This applies every time he steps, therefore the entire boat is permitted.)

Question: What is the difference between these answers?

Answer #1: They argue about if the boat's walls were diminished [from 10 Tefachim. Rabah's reason no longer applies, but R. Zeira's does];

Answer #2: They argue about one who jumped from one boat to another. (Rabah forbids, for he was not Shoves within these Mechitzos.)