1)

(a)Rebbi Meir, in whose opinion both a Jew and a gentile who are away for Shabbos, forbid the remaining residents of the Chatzer to carry - holds that a residence without residents is called a residence; Rebbi Yehudah, who permits them to carry, holds that it is not.

(b)In principle, Rebbi Yossi agrees with Rebbi Yehudah; however, he is concerned that the gentile may return on Shabbos, in which case he will forbid the other residents to carry (and they will be perhaps be unaware of his return and continue to carry).

(c)Rebbi Shimon specifically refers to a man going to stay with his daughter in the same town - because even if he falls out with his son-in-law, he will remain there; whereas if he went to stay with his son, and then fell out with his daughter-in-law, he will return immediately. Why is that? Because when a dog barks at a person, he still enters, but not when a bitch barks at him.

2)

(a)When the Tana Kama says that he requires a Mechitzah of ten Tefachim, either below or 'Mitoch Ugno' - he means either below the water surface (which will be explained shortly) or at least within the walls of the pit, even though Mechitzah does not reach the water.

(b)According to Rebbi Shimon ben Gamliel - 'Beis Shamai Omrim Milematah; Beis Hillel Omrim Milema'alah.

(c)According to Rebbi Yehudah, the Mechitzah that divides the two Chatzeros is good enough to divide the water in the pit, too - even though it does not extend to below the walls of the pit.

3)

(a)Rav Yehudah explains 'Milematah' of Beis Shamai to mean at the foot of the pit (actually touching the ground), and the 'Milema'alah' of Beis Hillel, above the surface of the water.

(b)The Gemara initially ascribed Rev Yehudah's rejection of Rav Huna's explanation of 'Lematah Mamash' (in Beis Shamai) - to the fact that according to Rav Huna, the water between the two courtyards joins underneath the Mechitzah.

(c)The problem with that is - that according to his explanation, too, by a pit that is deeper than ten Tefachim, the water between the courtyards will combine above the Mechitzah.

(d)The Gemara resolves the problem - by pointing out another statement by Rav Yehudah, where he says that the Mechitzah must protrude at least one Tefach from the water (Consequently, if the pit was twelve Tefachim deep, shall we say, the Mechitzah would have to be thirteen Tefachim tall). All this, according to Beis Shamai.

4)

(a)According to Beis Hillel, we are not worried about the water of the two Chatzeros mixing. What we are worried about is that it must look like a Mechitzah. Rav Yehudah asks on Rav Huna that, according to him, if the Mechitzah is on top of the pit, far from the water, then at the point of the water, where the Mechitzah is really needed, one does not see a Mechitzah.

(b)The problem with that is that - according to his opinion, too, no Mechitzah is visible in the water, where it should really be.

(c)The answer to that is a Beraisa quoted by Yakov Karchina'ah - which requires at least one Tefach of the wall to be submerged in the water.

5)

(a)Rav Yehudah permits one to carry underneath a beam of four Tefachim wide that stretches across the entrance of a ruin - because he follows the opinion of Rebbi Yishmael b'Rebbi Yossi, who permits a Mechitzah Teluyah even when it is not by water. Here too, he permits carrying under the beam, because we say on both sides 'Pi Tikrah Yored v'Sosem' (as if the square edge of the beam extended to the ground, enclosing the space in between).

(b)The Halachah is like Rav Nachman quoting Rabah bar Avuha, who permits the same beam that is suspended over a pit of water - in spite of the fact that the water mixes underneath the beam. This vindicates Rav Huna in the previous question, who permits a Mechitzah even when it is well above the water-level - not like Rav Yehudah, who requires that the Mechitzah is submerged one Tefach in the water. (See Tosfos DH 'Korah' and 'Ela', who learns this Machlokes concerning 'Pi Tikra Yored v'Sosem', and not a Mechitzah Teluyah.

(c)A Mechitzah Teluyah is only valid by water - exclusively, and not even by a ruin or in a courtyard.

6)

(a)A wall that starts from the ground upwards must reach a height of ten Tefachim (either directly, or through Levud) in order to be a Kasher Mechitzah (even if it does not reach the roof - because of 'Gud Asik Mechitzasah').

(b)Rebbi Yossi maintains that a wall starting from the top downwards - needs to be no more than ten Tefachim - just like a wall starting at the bottom. He holds 'Gud Achis Mechitzasah'; the Tana Kama does not.

(c)Rebbi Yehudah permits a Mechitzah Teluyah between two courtyards, even though it is not over water.

(d)

1. Rebbi Yehudah's Din may well be confined to Eruvin, which is mid'Rabanan - but not to Sukah (like Rebbi Yossi holds).

2. Rebbi Yossi's Din, on the other hand, may be confined to Sukah, which is only a Mitzvas Aseh, but not to Shabbos, which is basically an Isur Sekilah.

7)

(a)It may well not have been Rebbi Yossi who permitted a Mechitzah Teluyah one Shabbos in Tzipori - but his son, Rebbi Yishmael b'Rebbi Yossi, who succeeded him.

(b)They once forgot to bring a Sefer-Torah to one of the courtyards which had not made an Eruv. So they arranged sheets that were already hanging there to form a Mechitzah Teluyah between the house which contained the Sefer-Torah and the Shul. In the process, they formed a narrow Mavoy with no Pesach leading to any other house in the Chatzer, so that there was nobody in the 'new' Mavoy to forbid the residents of that house to carry there.

(c)The Gemara rejects the initial text of 'Parsu Sadin al ha'Amudin' - because it is only permitted to add to a makeshift Ohel that already exists on Shabbos, but not to make a new one. Consequently, we change the text to 'Matz'u Sadinim Perusim'.