1)

(a)The Gemara thought initially that they argue ...

1. ... by 'Lo Ervu' - in the case of a Mavoy that runs into a closed Chatzer: Shmuel permits carrying in a Mavoy that runs into a Rechavah, but not if it runs into a Chatzer which has no Eruv, because he holds 'Nir'eh mi'ba'Chutz ve'Shaveh mi'Bifenim' is Asur. Whereas Rav permits carrying in the Mavoy - because according to him,'Nir'eh mi'ba'Chutz ve'Shavah mi'Bifenim' is Mutar.

2. ... by 'Ervu' - in the case of a Mavoy that runs into a Chatzer which has an Eruv but which opens into a Reshus ha'Rabim on the opposite side: Shmuel permits carrying in the Mavoy, since they made an Eruv, whereas Rav forbids it - in spite of the Eruv, since one can see the Reshus ha'Rabim from the Mavoy at both ends (one beyond the Chatzer), and people go from one Reshus ha'Rabim to the other, via the Mavoy and the Chatzer.

(b)

1. 'Kalah le'Tzidei Rechavah' - means that if the Mavoy runs into the Rechavah at the side, meaning that one of the walls of the Mavoy simply extends to become part of the Rechavah, it resembles a Mavoy Mefulash and even Shmuel agrees that it is Asur to carry there, in spite of the Eruv.

2. 'Zeh Keneged Zeh' - means that, if the Rechavah opens into the Reshus ha'Rabim exactly opposite the Mavoy, then both Rav and Shmuel will agree that it is forbidden to carry in the Mavoy - even when the Mavoy opens into the middle of the Rechavah.

3. 'Rechavah de'Yachid' - means that, even if the Mavoy opens into the middle of the Rechavah, which Shmuel permits, that is only by a public Rechavah, but in the case of a private one, Shmuel will agree that it is forbidden.

(c)Because the owner may decide to build a house at the side of the Rechavah, and it will become a 'Mavoy she'Kalah le'Tzidei Rechavah', which is Asur, as we just explained.

2)

(a)Rav was worried that by a Mavoy which is flanked on one side by a sea, and on the other, by a large trash-heap - either the trash-heap will be removed, or that the sea will recede, leaving a layer of silt, which will simply become part of the Mavoy.

(b)The Mishnah which permits throwing from one's window on to a trash-heap in the Reshus-ha'Rabim - speaks by a public trash-heap, which we know will not be removed, whereas Rebbi was speaking about a private one, which the owner might remove at any time.

(c)No! the Chachamim of Rebbi disagree with him. They forbid carrying in that Mavoy.

(d)Mereimar put up nets at the end of the alleyways of Sura (which ran into the sea), and did not rely on the sea as a Mechitzah.

3)

(a)They placed a Lechi at one end, and a mat by the bend of the Mavoy, to serve as a Lechi.

(b)This is neither like Rav (who considers a bent Mavoy to be Mefulash, and therefore would require a Tzuras ha'Pesach) asks Rav Chisda, nor like Shmuel, who would require a proper Lechi at each end of the Mavoy, and not a mat, which the wind can easily blow down.

(c)They could have remedied the fault, according to Shmuel, by fixing the mat so that it should stand firm in the wind.

4)

(a)From the Mishnah 'Chatzer Ketanah she'Nifretzah li'Gedolah, Gedolah Muteres, u'Ketanah Asurah, Mipnei she'Hi ke'Pischah shel Gedolah' - we would have thought that the large Chatzer is permitted, because people from the street do not use it, whereas in our case, Rav teaches us that even when the Mavoy is open to the street, and people from the street will inevitably enter the Chatzer, carrying is nevertheless permitted in the Chatzer.

(b)Rav needs to inform us that the Mavoy is Asur - because otherwise we would have thought that 'Nir'eh mi'Bachutz, ve'Shaveh mi'Bifenim' is Mutar.

(c)From the Beraisa 'Chatzer she'ha'Rabim Nichnasin Lah be'Zu, ve'Yotz'in Lah be'Zu ... Reshus ha'Yachid le'Shabbos' - we would have thought that that only applies to when the two exits to from the Chatzer to the streets are not exactly opposite each other, but when they are, the Chatzer is no longer considered a Reshus ha'Yachid, and carrying in it will be prohibited. Therefore, Rav needs to tell us that it is nevertheless permitted.

(d)'Reshus ha'Rabim le'Tum'ah' - means that the Chatzer is considered a Reshus ha'Rabim with regard to 'Safek Tum'ah bi'Reshus ha'Yachid, Tamei, bi'Reshus ha'Rabim, Tahor' - because it is considered a Reshus ha'Yachid only if it is a hidden and discreet place (like Sotah, from which we learn the Din of Safek Tum'ah - unlike Shabbos, which has different criteria). A Chatzer which is used by the public can hardly be described in this way!

5)

(a)According to Rabah (who holds 'Zeh Keneged Zeh Asur'), Rav needs to inform us that, not only is the large Chatzer considered a Reshus ha'Yachid mi'd'Oraysa (if someone throws into it from the Reshus ha'Rabim), but one is even permitted to carry there, too (that the Rabbanan did not decree an Isur).

6)

(a)A Nadel is a centipede.

(b)A 'Mavoy he'Asuy ke'Nadel' - is a a large Mavoy that has many small Mavo'os branching off it, each of which, like the large Mavoy, leads into the Reshus ha'Rabim.

(c)Rava objects to Abaye's ruling (that the main Mavoy requires a Tzuras ha'Pesach, and each of the small Mavo'os, a Lechi or a Koreh) - because, assuming that his ruling followed the opinion of Shmuel (since no Tikun is required at the bend in the Mavoy - i.e. the point where the small Mavo'os meet the large one), why did did require a Tzuras ha'Pesach for the large Mavoy? And besides, how could Abaye ignore the incident in Neherda'a, where they also adopted the Chumra of Rav?

(d)Rava therefore ruled that each small Mavoy required a Tzuras ha'Pesach at the point where it met the large one, as well as a Lechi or a Koreh where it opened into the Reshus ha'Rabim.

7)

(a)Where one side-wall of the Mavoy extends further into the street than the opposite one (even by less than four Amos(, Rava maintains that the Koreh must come off at right-angles from the shorter wall across to the longer one, thereby precluding the area beside the longer wall from the Mavoy.

(b)Rava disagrees with Rav Tachlifa bar Kahana - because, in his opinion, 'Koreh Mishum Heker', and there is no Heker by a diagonal Koreh.

(c)Whereas Rav Tachlifa bar Kahana holds - 'Koreh Mishum Mechitzah', and a Mechitzah is valid even when it is at an angle.

(d)Rav Kahana bar Tachlifa will agree with Rava, that a Koreh must be placed at ninety degrees from the edge of the shorter wall - if the length of the diagonal Koreh would be in excess of ten Amos (since an entrance of more than ten is Pasul - as we have learnt in our Mishnah).

8)

(a)The Gemara suggests that those who permit carrying underneath the Koreh do so because 'Koreh Mishum Heker' (and the Heker exists even beneath the Koreh); whereas those who forbid it, hold 'Koreh Mishum Mechitzah' - and we now contend that 'Pi Tikrah Yored ve'Sosem' applies to the inner-edge of the beam..

(b)Both opinions could also agree that 'Koreh Mishum Heker' - and they argue over whether there is a Heker underneath the Koreh or not; alternatively, they could both hold 'Koreh Mishum Mechitzah' - and they argue over whether it is with regard to the inner or the outer-edge that we say 'Pi Tikrah Yored ve'Sosem'.

(c)Rav Chisda maintains that, in any event, carrying in the space next to the Lechi is prohibited - because, seeing as the Lechi has no prescribed width, and can be extremely narrow, we are afraid that a person will come to carry into the street.

(d)No! 'Bein ha'Lechayayim' - does not mean that a Mavoy requires two Lechayayim (in fact, it only requires one). Rav Chisda uses the term 'Bein ha'Lecheya'im' because he is referring to Lechayayim in general.

9)

(a)'le'Divrei ha'Matir, Asur, le'Divrei ha'Oser, Mutar' - means that according to the one who permits carrying underneath the Koreh (because it is its outer edge that is 'Yored ve'Sosem') forbids this Koreh altogether (since the point where it is Matir is not attached to the Mavoy, but at a distance from it); whereas according to those who forbid carrying underneath it, the Matir is flush against the outside of the Mavoy, in which case one may carry in that Mavoy.

(b)Rava forbids carrying in the Mavoy even in the latter case - because, in his opinion, the Koreh has to be above the Mavoy - not just flush against it.

10)

(a)'Haysah Koraso Meshuchah O Teluyah; Pachos mi'Sheloshah, Ein Tzarich Lahavi Koreh Acheres': Initially, the Gemara understood 'Meshuchah' to mean outside the Mavoy (like the case of Rami bar Chama), and 'Teluyah', to mean within the posts, but not quite reaching them. So we see that even if the Koreh is not above the Mavoy, it is Kasher, provided it is within three Tefachim - a Kashya on Rava.

(b)Rava explains Meshuchah to mean that it falls short of the walls on one side, and 'Teluyah', on both sides.

(c)The Chidush of Teluyah - is that we even say 'Levud' on two sides.

(d)Raban Shimon ben Gamliel disagree with the Tana Kama - inasmuch as, according to him, we say Levud, not up to three Tefachim, but up to four.