Assertion: Even if they put the Eruv in one of the houses next to the Chatzeros, or even in one of the houses of the Chatzeros, these three houses need not give an Eruv, for they become a Beis Sha'ar for the Chatzer that brings an Eruv through them to another Chatzer.

Explanation #1: Rashi connotes that this discusses Eruvei Techumim.

Question: In Shabbos (34a) it connotes that Rava does not discuss both Eruvei Chatzeros and Eruvei Techumim, for it answers "this is not difficult. This discusses Eruvei Chatzeros, and this discusses Eruvei Techumim";

If so, according to Rashi (that Rava discusses Eruvei Techumim), an Eruv Chatzeros [placed Bein ha'Shemashos] does not acquire. If so, what was the question here from Rava (against Rabanan, who discuss Eruvei Chatzeros)?!

Explanation #2 (R. Chananel): Rava discusses Eruvei Chatzeros, but [Chachamim] were more stringent about Eruvei Techumim, and [Eruvei Techumim placed Bein ha'Shemashos] do not acquire.

Support: Now it is a proper question. The expression "Tzei" (leave) that he said "leave and be Me'arev for us" applies even in the city, like "Tzei and hire workers for us."

Explanation: We are thinking that according to Rabanan, since [a gap of] three [Tefachim] is excluded from the law of Lavud, it is considered an opening.

Explanation: Agav (for parallel structure) with teaching "above 10", it taught also less than four by four [Tefachim].

Explanation #1 (Rashi): Two Tefachim and Mashehu width of the circumference is within 10. From the middle [of the width] and to here (one side) is a Tefach, and from the middle and to here (the other side) is a Tefach.

Rejection (and Explanation #2 - Rivan): These two Tefachim and Mashehu (that must be within 10) are of height, from below to above, for this window is eight Tefachim by eight Tefachim. Since the circumference is 24, you are forced to say that in the middle it is eight, since for every three Tefachim of circumference, there is one Tefach of diameter.

When you remove two Tefachim below and above, and also from the two sides, [a square] four by four remain. Therefore, the window must have within 10 [of the ground] two Tefachim and Mashehu of the length of Zekifas ha'Chalon (where it contains a square four by four) in its middle, so Mashehu of the square is within 10.

Explanation: He holds that a square Amah has a diagonal of two Amos

Observation: The judges of Kisari (who say so) are wrong, like it says in Sukah (8b), for we see that this is not so. The entire length and width combined is only two Amos! (The diagonal must be shorter.)

Even though there R. Yochanan's teaching is explained properly, here we can establish it only like the judges of Kisari. Just like it says there [in Sukah] that the judges of Kisari are wrong, likewise R. Yochanan's teaching here is wrong.

Question #1: How could the judges of Kisari err? We see that it is not so!

Question #2: Just like they said that a circle in a square is a quarter [less], i.e. than the entire square, they should have said that a square in a circle is a third [less] than the entire circle, which is half of the square inside!

Or they should have said that a circle in a square is a third [less], i.e. than the circle inside (just like they said that a square in a circle is a half [less] than the square inside).

Answer: Some say that the judges of Kisari discuss only area in the square and circle. Regarding this, their words are true;

When you make a square two Amos by two Amos, and make a circle inside two by two, and another square inside the circle, it turns out that the outer square is four pieces of an Amah by an Amah;

In the circle inside the square there are [the area of] three pieces of an Amah by an Amah, for a square is a quarter more than [of its own area] than the circle [inside];

The inner square has only two [square Amos], for it is half of the outer [square], i.e. a third less than the circle.

Answer #1 (cont.): The Gemara in Sukah and R. Yochanan here erred about their words (of the judges of Kisari). They thought that they discuss perimeter.

Support: Now it is fine that they mentioned half, for everything refers to the outer square. I.e. a circle in a square is a quarter, i.e. a quarter less than the outer square;

A square in a circle is half, from what remains in the outer square over the inner square (i.e. it is less than the circle one square Amah, which is half of [two Amos, i.e.] the excess of the outer square over the inner), which is also half the inner [square].

Explanation: This is only because there is no opening between them, so the Chatzeros cannot be Me'arev together;

However, if there is an opening in this wall and they were Me'arev, it is permitted to take down [from the wall] and bring to the houses, and from the houses we bring up on the wall.

Possibility #1: Our Mishnah is unlike R. Shimon, for according to him, one may bring down and bring [to the houses] even if they were not Me'arev, for he says below (89a) that roofs, Chatzeros and Karfifos are one Reshus for Kelim that were Shoves in them.

Possibility #2: It is even like R. Shimon. "Below" means below to the houses. It says so below (92a).

Question: According to Rabanan, why is it forbidden to take down to the Chatzer? Rabanan agree that Chatzeros are a Reshus for themselves!

Rav Yehudah said below (90b) "when you want to say according to R. Meir... according to Rabanan, roofs and Chatzeros are one Reshus, and Karfifos are one Reshus";

Rashi explained there that it is permitted to take from Chatzer to Chatzer according to Rabanan. He brought a proof from a Beraisa there, which teaches that "the people of the Chatzer and people of the balcony...

Suggestion: On the wall, since it is not convenient to use, it is considered like a Karfef. Therefore it is forbidden to take down according to Rabanan, for Chatzer and Karfef are two Reshuyos.

Rejection: Even if there is a wall in between it is forbidden to take below, for an Eruv does not help for a Karfef;

Even from his Karfef it is forbidden to move to his Chatzer, like it says above (23b) regarding "if the majority was seeded, it is like a garden, and it is forbidden";

If so, why does it discuss a wall between two Chatzeros? Even if he has his own wall in his Chatzer, it should be forbidden to use on top of it, if it is considered a Karfef!

Answer (Ri): Surely, it is not forbidden due to Karfef, rather, because they forbid each other.

Implied question: Why do Rabanan permit from Chatzer to Chatzer?

Answer: That is only when the each Chatzer was not Me'arev by itself, so Kelim of the houses are not common in the Chatzer;

However, if each Chatzer was Me'arev by itself, we decree lest they come to take out Kelim of the houses to the other Chatzer.

Support: It is proven like this regarding the people of the Chatzer and the people of the balcony, below (91b).