(Mishnah): People of the big city may traverse all of the small city. People of the small city may traverse all of the big city.

How is this? If someone in the big city placed an Eruv in the small city, or vice-versa, he may traverse all of it and 2000 Amos outside of it;

R. Akiva says, he has only 2000 Amos from the place of his Eruv.

(Gemara): Our Mishnah should say "people of the big city may traverse all of the small city. People of the small city may not traverse all of the big city. (They may go only within 2000 Amos of their city.)

Question: (If so, the next clause of our Mishnah is unlike the Reisha.) Why does it say "Keitzad'' (what is the case)?

Answer: [The correct text of our Mishnah] does not say "Keitzad''.

Question: (A city is considered like four Amos.) Does a city count like [four Amos of] the measure of 2000 Amos [of the Techum]?

Answer (R. Elazar): A city counts towards the measure of 2000.

Initially, people of Tiverya used to traverse all of Chamasah. People of Chamasah used to reach only until the Kipah (perhaps this refers to the source of the hot springs of Tiverya - Chazon Yechezkel). Nowadays (after houses were added), Bnei Chamasah and Bnei Tiverya are one city.

(R. Yirmeyah): A case occurred in which an old shepherd came and said in front of Rebbi "I remember that people of Migdal used to ascend to Chamasah and traverse all of Chamasah, and they reached the outer Chatzer close to the bridge.'' Rebbi permitted Bnei Migdal to ascend to Chamasah and traverse all of Chamasah, and reach the outer Chatzer, until the bridge.

Further, Rebbi permitted Bnei Geder to descend to Chamasah and ascend to Geder, but Bnei Chamasah may not ascend to Geder.

(R. Mana): This is due to authorities. (Bnei Geder would hit Bnei Chamasah who ascended to Geder - PNEI MOSHE.)

Rebuttal (R. Yosi bei R. Bun): This is not the reason. Rather, it is because our Mishnah taught that people of the big city may traverse all of the small city, but people of the small city may not traverse all of the big city.

(R. Yitzchak bar Nachman citing R. Chaninah): When do [the first Tana and R. Akiva] argue? It is when they put their Eruv in the city square, but if they put their Eruv in houses, even R. Akiva agrees [that they may traverse all the city and 2000 Amos outside of it].

Question (R. Ba brei d'R. Papi): If a city [in which others placed their Eruv] was Me'arev [by itself], and [others] put their Eruv in the city square, is it not as if they put their Eruv in houses?! (R. Akiva taught Stam, i.e. even if the city was Me'arev!)

If a city became desolate - R. Lazar says, he may traverse all of it, and outside of it 2000 Amos;

(Shmuel): He has only 2000 Amos from the place of his Eruv.

(R. Ba bar Kahana citing R. Chiya bar Ashi citing Rav): One who puts his Eruv in a Dir or Sahar (a field where animals graze) may traverse all of it and outside of it 2000 Amos. Is a Dir or Sahar not like [a city] that became desolate of houses and residents?! (He holds like R. Lazar.)

A new city, he measures [the Techum] from the houses. An old city, he measures from the wall.

Question: What is new, and what is old?

Answer #1 (R. Ze'ira citing Rav Chisda): If he built houses and afterwards built the wall, this is new. If he built the wall and afterwards built houses, this is old.

Answer #2 (R. Ze'ira): Both this and this are new [if the houses never reached to the wall]. What is old? It is one that had residents [up to the wall], and [even if it] became desolate.

R. Ze'ira holds like he taught elsewhere;

[Amora'im] argued about one who built nine [Tefachim] for the sake of a Karfef, and one (completed the Shi'ur of 10 Tefachim) l'Shem Dirah. R. Lazar said, even if he built [only] the 10th l'Shem Dirah, it is like a Dirah (one may carry in it without limit);

R. Ze'ira said, even if he built [only] the 10th l'Shem Dirah, it is not like a Dirah (one may carry in it only up to Beis Sa'atayim. Likewise, if there is space between the houses and the wall, the wall was not totally l'Shem Dirah, so it is not considered Hukaf l'Dirah. We explained this like PNEI MEIR.)

(Mishnah - R. Akiva (to Chachamim)): Don't you agree that one who was Me'arev in a cave has only 2000 Amos from the Eruv?!

Chachamim: This is only if it has no residents. If it has residents, he may traverse all of it and 2000 Amos outside.

The law of a cave is more lenient than on top of it. (No one dwells on top, so one has only 2000 Amos from the Eruv.)

We learned that one who measures his Techum gets 2000 Amos. Even if they end at a cave, he may not enter it. (The 2000 Amos were in addition to his four Amos, so we do not give him any more.)

(Gemara - R. Yakov bar Acha citing R. Eliezer): [According to R. Akiva,] one who acquires Shevisah in a Karfef, his law is more lenient than one who puts his Eruv in a Karfef;

One who acquires Shevisah in a Karfef, he may traverse all of it and outside of it 2000 Amos [for it is Reshus ha'Yachid]. One who puts his Eruv in a Karfef [more than Beis Sa'atayim, or if it was not Hukaf l'Dirah], he has only 2000 Amos from the place of his Eruv. (We explained this like PNEI MEIR.)

Question (R. Ze'ira): If he said "I should acquire Shevisah in a Karfef'' (is it as if he was Shoves in it, or as if he placed an Eruv in it)?

Answer (R. Chananyah brei d'R. Hillel): R. Meir and R. Yehudah argue about this. R. Meir says that the primary Eruv is a loaf. (One who declares Shevisah without a loaf cannot be more lenient than one who placed an Eruv (loaf). One who puts his Eruv in a Karfef has only 2000 Amos from the place of his Eruv;

R. Yehudah says that the primary Eruv is through one's feet. One who says "I should acquire Shevisah in a Karfef'' [it is as if he was Shoves in it, so] he may traverse all of it and outside of it 2000 Amos.

The roof of a tower is judged like a city (he has 2000 Amos outside of it). The roof of a cave is judged like fields (the cave counts towards his 2000 Amos).

Question: (Chachamim said, if it has residents, he may traverse all of it and 2000 Amos outside.) Do they mean actual residents, or proper for residents?

Answer: Since R. Yitzchak bar Nachman said in the name of R. Chaninah "you view it as if it were full of water and mud'', this teaches even if it is proper for residents.

Inference (R. Yitzchak bei R. Elazar): If a cave has two openings, if there are 3999 Amos between this [end of the roof] and this, he may traverse all of it and 2000 Amos outside [because the Techumim overlap]. If there are 4000 Amos between them, he has only 2000 Amos from the place of his Eruv.)

(R. Bari): R. Ze'ira explained, [overlap of Techumim is important, for] if someone put his sandals here [on the roof, 2000 Amos from one end], he may go outside (through the cave) and take them (for they are within 2000 Amos of the other end), and if he put his sandals here [past 2000 Amos from the other end], he may go outside and take them;

From here, he may go outside, and from here, he may go outside. [If it is open] from one side it is forbidden, from two sides it is permitted.

(R. Acha citing R. Chinena): If the roof of the cave was 3999 Amos, he may traverse all of it and 2000 Amos outside [because the Techumim overlap]. Even if the top of the [city] wall was very big, it is permitted.

If the roof of a cave was 6000 Amos, he may traverse all of it and 2000 Amos outside of it, through small date trees [along the way].

Question: [Binyan] in back of roofs - how much [may one carry in it]?

Answer #1 (R. Yosah citing R. Yakov bar Acha, and R. Iniya bar Pazi citing R. Yehudah, and R. Acha leaned to say so in the name of Shmuel): One may carry in it even a [Beis] Kor or two Korim;

Answer #2 (Rav): One may carry in it up to Beis Sa'atayim.

Question (R. Yosi bei R. Bun): Rav contradicts himself!

A Mishnah teaches that all roofs of the city are one Reshus. Shmuel said, this is up to Beis Sa'atayim. Rav said, it is even a [Beis] Kor or two Korim. (We explained this like PNEI MOSHE.)

In back of roofs and roofs themselves are the same. (We explained this like SHA'AREI TORAS ERETZ YISRAEL.)