1)

(a)When designating one's new place of residence (by the distant trunk of the tree) - he must still have time to run to the trunk and arrive there before nightfall (in effect, before Bein Hashemashos).

(b)When our Mishnah writes 've'Chashchah Lo' - it means that, by the time he arrived at his house (not by the tree-trunk) it had turned dark. Alternatively, it means that it became dark by the time he walked to the tree-trunk, but had he run, he would have reached it beforehand.

2)

(a)Rav Yosef informed Rabah - that he aware of that tree.

(b)Rabah told Rav Yosef - that he could rely on him, since he was, and Rebbi Yossi, in a Beraisa, permits one traveler (in the same circumstances) to make the Eruv on behalf of the other.

(c)He quoted Rebbi Yossi, although his name is not mentioned in the Beraisa, because 'Nimuko Imo', meaning that the Halachah is always like him, whenever he argues with a contemporary.

(d)'Nimuko Imo' is the acronym of 'Nim (word) ve'Kav' (straight and correct).

3)

(a)We learn from ...

1. ... "She'vu Ish Tachtav" - that a person who leaves his Techum has four Amos.

2. ... "Al Yetzei Ish mi'Mekomo" - the Techum Shabbos of two thousand Amos (though this is really an Asmachta, since the Pasuk is referring to collecting the Man - Mosaf Rashi).

(b)We prefer to learn "u'Matza Oso Go'el ha'Dam mi'Chutz li'Gevul ..." from the Pasuk "u'Madosem mi'Chutz la'Ir, than from that of "mi'Kir ha'Ir va'Chutzah" - since it is preferable to learn "Chutz" from "Chutz" than "Chutz" from "Chutzah".

(c)True, it does not matter if the two words of a 'Gezeirah Shavah' are not exactly the same, it does matter - but that is only if there is not another potential word which is. Then, we will rather learn the 'Gezeirah Shavah' from there.

4)

(a)We learn from "es Pe'as Kedmah" - that with regard to Techumin, one always adds the corners (i.e. to square a circular town).

(b)The problem with Rebbi Chanina ben Antignos is - that if he holds of the above 'Gezeirah Shavah', then he should also square the circle by Techum Shabbos, like by the cities of the Kohanim; whereas if he does not, then from where does he know the two thousand Amos of Techum Shabbos?

(c)Really, Rebbi Chanina ben Antignos does hold of the 'Gezeirah Shavah' (with regard to the two thousand Amos). However, the Torah also writes "Zeh Yihyeh Lahem Migreshei he'Arim", which implies 'Zeh' (only here, by the cities of the Levi'im), does the Din of Pei'os apply, but not by Shabbos.

Note: This entire Sugya appears to learn that Techumin is d'Oraysa - see Rashash.

(d)The Rabbanan learn from 'Zeh' - 'ka'Zeh Yihyu Kol Shovsei Shabbos', meaning that the concept of squaring the circle applies to all areas of Shabbos (even when we are speaking about a distance, and not an area), since that is the diagonal of a square of four Amos). Consequently, four Amos on Shabbos becomes five and three fifths Amos .

5)

(a)All cases of four Amos with regard to Shabbos - really means five and three fifths Amos, as we just explained.

(b)Rava asked his disciples whether, if someone throws something from the street on to a board of four Amos square that is placed on a pole (and for which he is Chayav) - 'four Amos' should be taken literally, or whether it means five and three fifths Amos.

(c)Rav Papa and his friends answered - like the second side of the Sha'aleh, as we learnt above.

6)

(a)According to Rav Nachman, Rebbi Meir and Rebbi Yehudah argue over whether 'Ikar Eruv be'Pas' (Rebbi Meir) - which explains why he is strict with regard to a rich man making an Eruv be'Regel; or 'Ikar Eruv be'Regel' (Rebbi Yehudah) - which explains why he permits it.

(b)Rebbi Yehudah agrees that - even an Eruv be'Regel is only permitted across the board if one is standing on the spot; making an Eruv in the distance, is confined to a poor man (who is traveling), but a rich man cannot do this.

(c)According to Rav Nachman - the author of 've'Zu Hi she'Amru, he'Ani Me'arev be'Raglav' is Rebbi Meir, and the Chidush is that, although 'Ikar Eruv be'Pas', Chazal nevertheless permitted a poor man (i.e. a traveler) to be Me'arev be'Raglav.

(d)And the author of 'Lo Amru Me'arvin be'Pas Ela Lehakel Al he'Ashir she'Lo Yetzei vi'Ye'arev be'Raglav' - is Rebbi Yehudah (because, according to Rebbi Meir, that is the Ikar Eruv).

7)

(a)According to Rav Chisda, both Tana'im hold 'Ikar Eruv be'Regel' -Consequently, Rebbi Meir agrees with Rebbi Yehudah, that even a rich man can make an Eruv be'Regel - provided he goes to the spot where he wants to be Koneh Shevisah.

(b)He disagrees with him however - when it comes to making an Eruv be'Regel from a distance: Rebbi Yehudah permits this even by a rich man, whereas Rebbi Meir restricts it to a poor man.

(c)According to Rav Chisda - the Seifa 'Lo Amru Me'arvin be'Pas Ela Lehakel Al he'Ashir she'Lo Yetzei vi'Ye'arev be'Raglav' - goes according to Rebbi Meir, as well as Rebbi Yehudah.

8)

(a)Since we rule like Rav Nachman, a rich man is not permitted to make an Eruv be'Regel from his house; whereas, according to Rebbi Meir, he is not even permitted to make an Eruv if he walks to the spot where he wishes to be Koneh Shevisah.

(b)Rebbi Yehudah brought a proof from the poor men of Kfar Shichin and Kfar Chananya, who made an Eruv on foot to go and fetch dried figs and raisins in a year of famine, from the residents of Aruma. Now the poor men of Kfar Shichin and Kfar Chananya were living at home, had the Din of rich men - yet they were permitted to make an Eruv on foot, something which Rebbi Meir forbade.

9)

(a)From the fact that Rebbi Yehudah permitted only the man who set out to travel to the neighboring town to complete the journey of four thousand Amos, and not the other residents of the town (even if they would have made an Eruv be'Regel) - is a proof for Rav Nachman; because according to Rav Chisda, even a rich man can also make an Eruv be'Regel on foot.

(b)We are forced to say ...

1. ... that the man set out to go to his house in the second town - because if he just went to be Koneh Shevisah, he would still be a rich man, in which case he would be no different than any other of the town's residents.

2. ... that he owned a house in the other town too - because, that is how we know that he set out to go and reside there (which made him an Ani) and not just to be Koneh Shevisah at a point somewhere in the middle.

3. ... that he did not say 'Shevisasi be'Makom Peloni' - first of all, because the Mishnah does not record him as having said so, and secondly, because if he had, then Rebbi Meir, who agrees that he is an Ani (otherwise, he should have forbidden him to move at all, and not just restricted him to 'Chamar Gamal'), would have validated the Eruv completely.

10)

(a)Every Friday, Rabah bar Rav Chanan would designate a specific spot between his residence in Artivna and his destination in Pumbedisa as his new Makom Shevisah.

(b)Abaye reminded him that that was the opinion of Rav Chisda, who maintained that Rebbi Yehudah permits an Ashir to be Me'arev be'Raglav, even from his house, but that, according to Rav Nachman, this was prohibited. So he retracted.

11)

(a)Our Mishnah writes that they only permitted to make an Eruv with bread in order to be lenient with the Ashir - Now if we were to restrict the concession of 2004 Amos to someone who makes his Eruv on foot, then making an Eruv with bread would also incorporate the stringency of being confined to 2000 Amos (instead of 2004); so how can the Mishnah refer to Erav be'Pas as a leniency?

(b)The answer is - that since the rich man is spared having to walk to his Techum to wait for night (but is able to send his Sheli'ach), the Mishnah is justified in calling it a leniency (despite the fact that, in other area, an Eruv made with bread might result in a stringency).