1)

(a)If a courtyard which opens into two Mavo'os ...

1. ...did not make an Eruv with them - then neither of the courtyards that flank the courtyard on the other side is permitted to carry objects into the Mavoy (assuming that the residents of the courtyard tend to use both Mavo'os).

2. ... did make an Eruv with both Mavo'os - then they are permitted to carry into it, but not vice-versa (like Shmuel just said above).

(b)In the former case, where the Chatzer did not make an Eruv with both Mavo'os (but only with one of them), the residents that Mavoy will be permitted to carry into the Mavoy - provided the members of the courtyard do not tend to use the other Mavoy.

(c)The residents of the Mavoy through which the residents of the courtyard are accustomed to walk, are permitted to carry in their own courtyard, in spite of the fact that they did not make an Eruv together - if the residents of the other Mavoy made an Eruv with the Chatzer, since the Mavoy which had been accustomed etc., did not join in the Eruv.

(d)If the Mavoy which the residents of the one Chatzer tended to use made its own Eruv, but neither the Chatzer nor the second Mavoy did likewise - then, to ensure that the members of the Chatzer do not forbid the members of the Mavoy to carry, in spite of their Eruv, we force the members of the Chatzer to use the other Mavoy - because of 'Kofin Oso Al Midas Sedom' (since it makes absolutely no difference to them which Mavoy they use, though it does make a difference to the residents of the Mavoy which made an Eruv.

2)

(a)Shmuel invalidate the Eruv of someone who is fussy that his bread should not be eaten by any of the participants - because such an attitude negates the whole purpose of an Eruv, which is to combine the various parties concerned (as the very word 'Eruv' suggests).

(b)The men of Vardina were known for their stinginess.

(c)Beis Hillel only validates an Eruv that is placed in two receptacles - when this is due to the one receptacle being full. If however, the Eruv is deliberately divided into two receptacles, it is Pasul - because here too, it negates the concept of merging, which is the essence of Eruv.

3)

(a)Although both the person who is fussy about his Eruv being eaten, and someone who is fussy about placing his Eruv in the same receptacle as the others' - negate the concept of combining, they do so in different ways; the one does not want his Eruv to be eaten, but does not care where it is placed, whilst the other one is just the opposite, so perhaps we would not learn one from the other. Therefore Shmuel needed to tell us both Dinim.

(b)When Shmuel exempts the person in whose house the Eruv (bread that was collected from each of the participants) is placed, from placing his bread - he exempts him altogether from the need to place bread, since his house has been designated for the Eruv, it is as if everyone in that courtyard was living there, so why should he need to place bread?

(c)The Gemara initially thought - that Shmuel was exempting him from placing his bread together with the others, because, wherever the bread is lying, it will combine with the other loaves (from which we would have inferred that all the bread does not need to be placed in the same receptacle).

4)

(a)Shmuel holds 'Eruv Mishum Kinyan'. Nevertheless, in his opinion, money may not be used - because people will think that one is obligated to use money, and refrain from making an Eruv (which is only permitted for a Devar Mitzvah), even when they have bread.

(b)Rabah holds that 'Eruv Mishum Dirah' - because people's minds are on their bread, and where their bread is, that is where they are domicile. It is as if that was the only house in the Chatzer.

(c)'Me'arvin bi'Chli' means - that instead of using bread, one may use any object which serves to acquire the Reshus of the person who gives his house for this purpose.

(d)The other two differences between the two reasons - is if the bread is (more than enough for two meals, but) less valuable than a Shaveh Perutah, or whether a Katan can acquire the Eruv on behalf of any of the residents: If 'Eruv Mishum Kinyan', then it will not be valid, in either case; whereas if 'Eruv Mishum Dirah', then it will.

5)

(a)The Eruv does not acquire only on his own behalf (according to Shmuel) - nor does only he become a resident (according to Rabah) - because the fact of the matter is, that he was acting on behalf of them all, and we apply the principle 'Shelucho shel Adam Kamoso' (nor is it clear why the Gemara thought that this was not the case).

(b)The Gemara rules like Rebbi Shimon - that if the middle Chatzer made an Eruv with the two outer ones, they are permitted to carry in the middle Chatzer, and vice-versa (like Rav on 48b).

6)

(a)A traveler who is approaching town, and who wants to be Koneh Shevisah anywhere up to two thousand Amos ahead of where he is - can designate any landmark that he is aware of (a tree or a wall) within that space - even though he cannot actually see it - as his residence. Subsequently, he will be able to walk two thousand Amos from there.

(b)He then measures his two thousand Amos ...

1. ... in a circle from where he is standing - according to Rebbi Chanina ben Antignos.

2. ... the Chachamim in the form of a square - according to the Chachamim (because according to them, he always gains the corners - the quarter that a square is more than a circle).

(c)According to Rebbi Yehudah, Chazal instituted the concept of an Eruv using bread - for the benefit of the rich man, to save him from having to walk from his house to the border to wait for the entry of Shabbos; an Eruv with bread enables him to send a Sheli'ach.

(d)According to Rebbi Meir, they instituted the concept of Eruv on foot - for the benefit of the traveler, who has no bread with him.

7)

(a)According to Rav, when Rebbi Meir in our Mishnah says 'Lo Amar Klum, he means nothing at all, not even four Amos - since, due to the fact that the spot that he designated is not clear-cut, he does not acquire it as his place of residence; on the other hand, he relinquished the spot where he was standing when Shabbos entered. As a result, he ends up with neither the one nor the other.

(b)According to Shmuel, 'Lo Amar Klum' - means to grant him the right to go the full two thousand Amos from the far end of his new Techum - where his house is situated (because since the four Amos that he designated are unspecified, we reckon the spot that he designated to be the first four Amos at the near end of the tree, whereas his house is two thousand Amos from the far end.

(c)When Shmuel says 've'Na'aseh Tachtav shel Ilan Chamar Gamal' - he means that, on the one hand, we reckon his four Amos from the nearest point of the tree (as we just explained in b.); and on the other, that, when it comes to going two thousand Amos in the opposite direction (the one from which he came), we reckon his four Amos from the furthest point of the tree, thereby minimizing his two thousand Amos in that direction. In fact, we go strict both ways.

8)

(a)Rashi's second interpretation of 'Lo Amar Klum', according to Shmuel - is that he cannot walk two thousand Amos from the far side of the tree to his house. He may however, walk the two thousand Amos between where he is and the tree, because one way or another, he is Koneh Shevisah, either where he is, or by the three. However, since we do not know which one, we are strict, permitting only the area which incorporates both.

9)

(a)The Gemara does not probe Shmuel's reason for Rebbi Meir - because it is obvious. In his opinion, Rebbi Meir holds (according to Rashi's first explanation) that he is definitely Koneh Shevisah under the tree, only we don't know at which point.

(b)Rav's reason is - either because one cannot be Koneh Shevisah by a point which is not clear-cut; or because - 'Kol she'Eino be'Zeh Achar Zeh, Af be'Bas Achas Eino' (Any two things which cannot become effective in succession, cannot become effective simultaneously either).Here, since he did not clarify which four Amos under the tree he was designating, what he was in fact saying, was that all eight Amos under the tree should be Koneh Shevisah. And that remains totally ineffective, since he cannot acquire first one of the four Amos, and then the other.

(c)If he were to specifically designate four Amos out of eight - he would still not be Koneh Shevisah according to the first reason (since the four Amos would still not be clear-cut); whereas, according to the second reason - he would be Koneh Shevisah, since this is not a case of 'Bas Achas'.