1)

(a)Rava changes the text of the Beraisa (as Rav Nachman explains). According to him, the Reisha, which differentiates between the large town and the small town, is speaking about measuring (as is Rebbi Yehoshua ben Levi); with regard to placing, that is dealt with in the Seifa of the Mishnah.

(b)The source of Rebbi Yehoshua ben Levi's Din of 'Kalsah be'Chatzi ha'Ir Ein Lo Ela Chatzi ha'Ir' is the very next Mishnah at the foot of the Amud, which says that even if the two thousand Amos Techum end in the middle of a cave, he only has until there, and is not permitted to go any further, even to the end of the cave.

(c)Rav Idi said 'Ein Elu Ela Divrei Nevi'us' - about the second half of Rebbi Yehoshua ben Levi's statement.

2)

(a)Since the purpose of this Dakah is to remove the fear from the inhabitants of the town (who are afraid to fall into the deep wadi - a Dakah of only four Tefachim would be inadequate for that purpose.

(b)If there is no Dakah - then each house reckons the Techum Shabbos from its front door, because, due to the constant fear of falling into the wadi, it is a town which stands to be disbanded (like we learnt above (56b).

(c)Rav Yosef maintained that Rebbi permitted the inhabitants of Geder to walk down to Chamsan, but not vice-versa - because Geder had a Dakah (from which they measured two thousand Amos - encompassing Chamsan, when one reckoned from the Dakah); whilst Chamsan did not, and if one reckoned from their individual houses, Geder fell outside the two thousand Amos.

3)

(a)According to Rav Dimi, Rebbi forbade the inhabitants to go to Geder on Shabbos - because the B'nei Geder used to attack them and beat them.

(b)Rebbi was not afraid that they would attack them even in Chamsan - because people tend to be more subdued when they are away from home.

(c)Nor was Rebbi afraid that the inhabitants of Chamsan would beat the inhabitants of Geder, who were clearly not subordinate to them.

(d)This only tended to occur on Shabbos - because on Shabbos, people drink more wine, as a result of which drunkenness and sometimes hooliganism, is more common.

4)

(a)According to Rav Safra, Chamsan was a town in the shape of a bow, whose two ends were more than four thousand Amos apart, and who, as a result, had to measure from the front-door of each individual house (rendering Geder, which was the string of the bow more than two thousand Amos from the end of it. The inhabitants of Geder however, who measured from the wall closest to Chamsan, found that Chamsan lay within the Techum.

(b)According to Rav Idi bar Chinena, Geder was a large town, whose Techum encompassed Chamsan, whereas Chamsan was a small town, whose Techum did not encompass Geder.

5)

(a)The Rabbanan agree with Rebbi Akiva, that if someone places his Eruv in the middle of a cave, that he measures two thousand Amos only from there, and not from the far end of the cave - because there are no residents there; whereas if an Eruv is placed in the middle of town, they count the town as four Amos - because of the residents.

(b)The Rabbanan differentiate between an Eruv that is placed inside the cave in which people dwell (where they give the entire cave plus two thousand Amos), and one that is placed on top of it, which only has two thousand Amos from where the Eruv is.

6)

(a)Shmuel holds that, according to the Rabbanan, someone who is Koneh Shevisah in a ghost-town with Mechitzos, may consider the town to be four Tefachim, and they may walk two thousand Amos outside it; whereas if he places his Eruv there, he will only have two thousand Amos from where he places it.

(b)Shmuel connects his statement to the Rabbanan, because, according to Rebbi Akiva, this Halachah would apply equally to a town which is inhabited.

(c)Rebbi Elazar does not differentiate between someone who places an Eruv and someone who is Koneh Shevisah. Either way he says, according to the Rabbanan, he has the whole town plus two thousand Amos.

(d)According to Rebbi Elazar, when the Chachamim in our Mishnah agree with Rebbi Akiva that by a town which has no residents, one's Eruv is Koneh two thousand Amos from where his Eruv is, and not from the edge of the town - they mean, not a town which has no residents, but one which is unfit to accommodate them (i.e. whose walls fell down).

7)

(a)'Shavas be'Ir Afilu Hi Gedolah ke'Anti'ochya, bi'Me'arah, Afilu Hi k'Me'aras Tzidkiyahu ... Mehalech es Kulah v'Chutzah Lah Alpayim Amah'. If we deduce 'Ir Dumya d'Me'arah' - then we will be speaking about a town which is devoid of residents (but which has walls - otherwise he would not be permitted to walk the entire town). Nevertheless the Beraisa permits only Shavas (Koneh Shevisah), but not Hini'ach (when he placed his Eruv) - a Kashya on Rebbi Elazar.

(b)The Gemara did not answer that the author of the Beraisa is Rebbi Akiva, because if it would be - then why does the Tana confine the case to a ghost-town, since according to Rebbi Akiva, the same will apply to a town that is inhabited.

(c)Rebbi Elazar changes the deduction to Me'arah Dumya d'Ir (meaning that both are inhabited) - and only Shavas has two thousand Amos, but not Hini'ach. And that being the case, the author of the Beraisa will be Rebbi Akiva.

(d)'k'Me'aras Tzidkiyahu' means, not uninhabited like Tzidkiyahu's cave, but large like it.

8)

(a)Mar Yehudah told the inhabitants of Mavrachta (who had placed their Eruv in the Shul of Bei Agubar) to place it Eruv further inside, in order to extend the limits further (like Rebbi Akiva, who reckons two thousand Amos from wherever the Eruv is, and not from the end of the town).

(b)Rava called him 'Palga'ah (quarrelsome) - because nobody contends with Rebbi Akiva.

9)

(a)'Someone who does not agree with the concept of Eruv' in our Mishnah - refers to a Kuti (who did not tend to accept Rabbinical rulings of any sort).

(b)A Jew who wishes to carry in a courtyard which is shared with a gentile or with someone who does not agree with the concept of Eruv - must hire from him his rights in the courtyard.

(c)According to Rebbi Eliezer ben Ya'akov - it is only when at least two Jews share the courtyard with the gentile that this is necessary, but not when there the courtyard is shared by a Jew and a gentile.

10)

(a)Raban Gamliel gave testimony that his father had told them (after they had been Mevatel his Reshus to them) to quickly move their vessels into the Mavoy to make a Chazakah - before the Tzedoki changed his mind and put his vessels there (thereby retracting from his Bitul Reshus).

(b)Raban Shimon ben Gamliel considers a Kuti a gentile, but not a Tzedoki. From a gentile or from a Kuti one has to hire his rights in the Chatzer, and from that he cannot retract; whereas a Tzedoki, like any other Jew, can simply be Mevatel his rights (without any form of Kinyan). And there is nothing to stop him from retracting.

(c)Rebbi Yehudah holds that even moving their vessels into the courtyard would not have helped them, had the Tzedoki chosen to retract after that, and that the only guarantee they had of achieving whatever they wished to achieve in the Chatzer, was by doing it before Shabbos.