1)

(a)According to Rashi's first explanation - Rav Huna bar Chinena built a room of four walls made from canes (a Mechitzas Arev) in the orchard in which the shady tree was situated (to enable the Resh Galusa to eat orchard on Shabbos). This room was considered a guard's hut, since they were now able to leave the food and accessories there overnight, together with a guard. Since the walled orchard now contained a guard's-hut, he now considered it Hukaf le'Dirah, in which it was permitted to carry on Shabbos.

(b)Rava, who disagreed with that Tikun (for reasons that will be explained shortly), went and pulled out the canes.

2)

(a)

1. By a new town (one whose walls have been built before it is fully inhabited), one measures the Techum Shabbos - two thousand Amos - from the edge of the houses, and not from the outer city wall; whereas the Techum of an old (inhabited) town, one measures from the wall. So we see, Said Ravina - that in order to be considered Hukaf le'Dirah, it is necessary for the dwelling to precede the walls, which was not the case, by the Resh Galusa's orchard.

2. From a builder's wall, which is a makeshift wall constructed by the builders to protect them from the sun, and which does not have the status of a wall - we can derive, says Rav Papa, that the makeshift 'room', which stood to be demolished after a few days, did not have the status of a guard's-hut, to permit an area of more than a Beis Sasayim.

3. And Rav Huna Brei de'Rav Yehoshua prove Rava right from Rav Huna - who holds that a wall that is built purely to protect what is inside or behind it is not considered a wall. Similarly, Rav Huna bar Chinena's room was built to protect the food etc., and should not be considered of sufficient importance to permit carrying in the Karpaf that was more than a Beis Sasayim.

(b)Rav Huna in turn, derived his ruling from Rabah bar Avuha, who required a separate Eruv for each district of Mechuza, in spite of the fact that the town already had four walls (and one would have thought that he could have combined the entire town in one Eruv). Why? Because the walls, which were built, not to protect the inhabitants of the city, but to guard the 'Peira de'Bei Mechuza' (long trenches in which they kept the date-pits to feed their oxen), where not considered Mechitzos. Similarly, the room built by Rav Huna bar Chinena was not considered a room, since it was built mainly to protect the food that was inside it - and even the guard was placed there to protect the food exclusively, and would be effective to make an area Hukaf le'Dirah only if it was a Beis Sasayim or less.

(c)The Resh Galusa remained unimpressed. 'They know how to do bad (to forbid)', he said, 'but not how to do good (to permit)'!

3)

(a)According to Rashi's second explanation - it was a question of an Achsadra or a tent in an orchard of more than a Beis Sasayim, which was not Hukaf le'Dirah. The Resh Galusa wanted Rav Huna bar Chinena to turn the orchard into a Hukaf le'Dirah, so he built a path fenced on both sides by canes less than three Tefachim apart, which now enabled the Resh Galusa to carry from the house to the orchard, and in the orchard itself.

(b)Rava pulled out the posts - because, in his opinion, the Achsadra or the tent that was already there made the orchard Hukaf le'Dirah, so that the fenced-path of canes was unnecessary.

(c)According to this explanation, when the Resh Galusa quoted the Pasuk "Chachamim Hemah, Leha'ra, u'Leheitiv Lo Yada'u" - he was referring to the three Amora'im who, the day before, corroborated Rava's actions, even going so far as to remove the canes completely, so that Rav Huna bar Chinena should not re-place them; whereas on that day (when it was too late) they realized their mistake, to go back on their original ruling and forbid carrying there without the Tikun of Rav Huna bar Chinena.

4)

(a)Rebbi Ilai in our Mishnah, quoting Rebbi Eliezer, permits carrying in a garden or in an enclosure the size of a Beis Kur (which is thirty Sa'ah); According to Chananyah, Rebbi Eliezer permits carrying, even in an area of forty Sa'ah.

(b)Both Tana'im learn from the fact that the Pasuk refers to the town as a Chatzer - that the large Rachbah behind the King's palace was the size of an average town.

(c)The basis of their Machlokes - is whether an average town is thirty Sa'ah or forty Sa'ah.

5)

(a)Chizkiyah had fallen ill, and Yeshayah had arrived in his Chatzer - to establish a Yeshivah there - in order to keep away the Angel of Death.

(b)This is not something that we should do - because it only invites the Angel of Death to fight against those who dare to defy him (though this did not apply to Yeshayah, who was a total Tzadik - Ritva).

6)

(a)Rebbi Ilai in our Mishnah (who permits the members of the Chatzer who remembered to make an Eruv, to carry from the house of the one who forgot to the Chatzer - and vice-versa - but not the person himself), must be speaking when the person who forgot was Mevatel his Reshus to them - because otherwise, they would not even be permitted to carry from their own houses into the Chatzer, since the section of Chatzer owned by the person who forgot to make an Eruv, would forbid them all to carry into it.

(b)Although he is allowed to carry from their houses to the Chatzer, he is not allowed to carry from his own - because, if he would be, he would no longer take his own nullification seriously, and continue to treat it as if he had not nullified it.

(c)The author of the Mishnah which forbids even the other members of the Chatzer to carry from his Reshus to the Chatzer - is the Rabbanan, whereas the Tana who permits it is Rebbi Eliezer, as Rebbi Ilai explicitly writes in our Mishnah.

7)

(a)Rebbi Eliezer only permits those who made the Eruv to carry from his house to the Chatzer when he said that he nullifies his ownership in the Chatzer (as explained earlier). According to him, this incorporates his house, which need not be specifically mentioned; whereas according to the Rabbanan, since he did not specify his house (only his portion of the Chatzer), it is not included in his Bitul.

(b)Rav Sheshes, who finds it necessary to point this out - is teaching us that their opinions extend to a case where five people lived in the Chatzer, and the one who forgot to make an Eruv nullified his ownership to one of them: Rebbi Eliezer (who holds that a person nullifies his ownership liberally) will say here too, that when he nullifies to one of them, he nullifies to them all; whereas according to the Rabbanan, it is necessary to nullify his ownership to each one of them independently.

(c)According to Rav Tivyomi, Rav Sheshes said directly (with regard to the Beraisa which ruled that when a member of a Chatzer who did not make an Eruv is Mevatel his Reshus, he does not need to be Mevatel it to each one individually) that the author of this Beraisa is Rebbi Eliezer.

(d)Rav Kahana and Rav Tivyomi argue - over whether Rav Sheshes explained the Machlokes Rebbi Eliezer and the Rabbanan on our Mishnah (with regard to negating his Reshus ownership in the Chatzer without mentioning his house), in which case it is Rachbah and Rav Huna bar Chinena who extended their argument to the question of whether negating his ownership to one out of four, covers the other three as well; or whether Rav Sheshes explained their Machlokes on the Beraisa directly with regard to the latter point.

8)

(a)Rebbi Eliezer's reason is ...

1. ... either because someone who negates his ownership of his Chatzer automatically includes that of his house - in which case, if he specifically precludes his house, it will indeed be precluded; or because people do not tend to live in a house without the Chatzer, in which case, even if he specifically precluded his house from the nullification, we will ignore this, because 'Batlah Da'ato Etzel B'nei Adam'.

2. ... Similarly, the Rabbanan's reason is either because - he confined his nullification to his Chatzer, but not to his house, in which case, if he were to specifically include his house, we would say that it is indeed included; or because a person does not usually withdraw completely from his property. Consequently, even if he were to say that he includes his house, it will not be included, because 'Batlah Da'ato Etzel B'nei Adam'.

(b)The Gemara concludes - like the first side of the She'eilah in both cases. So both according to Rebbi Eliezer and according to the Rabbanan, his condition stands.

(c)Arkablin - is a thick creeper that grows around the tree and that resembles vine-branches. It grows very compact and has a bitter taste.

9)

(a)Anything can be used for a Eruv - except for water and salt.

(b)This is because - water and salt are the only two commodities which do not satisfy at all.

(c)According to Rashi - the Mishnah is speaking referring to both Eruvei Chatzeros and Eruvei Techumin.

(d)Someone who makes a Neder not to eat food is forbidden to eat anything other than water and salt.

10)

(a)Yes, one may make an Eruv of wine for a Nazir, of Terumah for a Kohen or for a Kohen in a Beis ha'Peras.

(b)Sumchus disagrees - with making an Eruv of Terumah for a Yisrael. According to him, only Chulin may be used for a Yisrael.

(c)Rebbi Yehudah permits even making an Eruv for a Kohen in a graveyard - because it is possible for the Kohen to eat it without transgressing the laws of Tum'ah - by entering it in an enclosed carriage (the reason for this will be explained later).

(d)The underlying principle of Eruvei Chatzeros and Techumin - is that a person considers there where he eats (where his food is) to be his home. Consequently, when each of the residents of a Chatzer put food in the kitty, which is placed in one house, it is as if that residence is their shared property - as if they were members of one family. Similarly, when a person places food at a certain point outside the town (but not more than at a distance of two thousand Amos), it is as if that point because his new home, and he is now permitted to walk to any point not more than a radius of two thousand Amos from there.