1)

(a)The water of rivers and fountains cannot be Koneh Shevisah - because it is constantly moving.

(b)Perhaps, suggests the Gemara, Rebbi Ya'akov bar Idi heard from Rebbi Yehoshua ben Levi - that the Halachah is always like the more lenient opinion by Eruv (from which he deduced that the Halachah is like Rebbi Yochanan ben Nuri, who holds that a sleeping man is Koneh Shevisah).

(c)The Chumra that emerges from Rebbi Yochanan ben Nuri's ruling is -'Cheftzei Hefker Konin Shevisah'.

(d)Had he only ruled 'Halachah k'Divrei ha'Meikil b'Eruv' - we would have confined that ruling to an individual who argues with an individual, or a number of Tana'im who argue with a number of Tana'im, but not to an individual who argues with a number of Tana'im (where the regular principle of following the majority will apply). That is why he needed to add the ruling 'Halachah k'Rebbi Yochanan ben Nuri', even when he is the minority.

2)

(a)Rebbi Eliezer holds that a young woman who sees blood after ninety days - is not Temei'ah retroactively (as most women are). Consequently, any Taharos which she handled prior to her sighting blood, remain Tahor. According to the Rabbanan, we only say this with respect to an older woman, who has reached the age of menopause.

(b)'After he remembered' means after Rebbi remembered that it was not an individual who argued with Rebbi Eliezer, but the Rabbanan, he decided that nevertheless, Rebbi Eliezer was sufficiently worthy to rule like him in case of an emergency. It cannot mean after he remembered that the Halachah was not like Rebbi Eliezer (in fact, no ruling had as yet been issued), - because in that case, how could he rely on his opinion, even in a case of emergency?

(c)Rebbi considered that case one of emergency - because it was a year of drought, and it would have been a big loss to have declared the food in question, Tamei.

(d)From here we see, asked Rav Papa on Rava - that even by a de'Rabbanan (such being Metame a woman retroactively), we will not follow a minority opinion to be lenient (since Rebbi only relied on Rebbi Eliezer because it was a case of emergency).

3)

(a)Shiv'ah - refers to the prohibition of washing oneself and one's clothes; Sheloshim - to having a haircut and ironing one's clothes.

(b)Shemu'ah Rechokah, according to Rebbi Akiva - applies for only one day.

(c)Rabah bar bar Chanah in the name of Rebbi Yochanan - rules that whenever an individual argues with a majority to take on a more lenient approach (even by a de'Rabbanan), we follow the majority opinion, except for this case - because it concerns Aveilus, and Rebbi Yochanan concurs with Shmuel, who holds 'Halachah ke'Divrei ha'Meikel be'Avel'.

(d)So we se once again, asks Rav Mesharshaya on Rava, that even by a de'Rabbanan, we do not accept the minority ruling to go to the lenient side, when it clashes with a majority opinion,

4)

(a)Rebbi Yehudah, who requires the knowledge of the person making the Eruv Techumin, concedes that this is not necessary by Eruvei Chatzeros. The reason for this is because, whereas making an Eruv Techumin in the one direction may cause him a loss (by disallowing him the two thousand Amos that he was initially permitted in the opposite direction - and one cannot cause someone a loss without his knowledge and consent), making an Eruv Chatzeros on someone's behalf, cannot possibly so him any harm, and does not therefore, require his consent.

(b)Had Rebbi Yehoshua ben Levi issued only the one ruling (that of 'Halachah ke'Divrei ha'Meikel be'Eruv') - we would have established that by the food of an Eruv that diminished to less than the initial two meals required for an Eruv. There, Rebbi Yossi declares the Eruv to be still valid, since initially, the Eruv contained the full amount. But regarding other disputes that concern the initial status of an Eruv, he will perhaps take the stringent view. Therefore, he needed to rule like Rebbi Yochanan ben Nuri, who speaks about the initial status of an Eruv.

5)

(a)When Rebbi Yossi said 've'Lo Amru le'Arev Chatzeros Ela Kedei she'Lo Leshakach Toras Eruv min ha'Tinokos - he meant to say that intrinsically, it is only Eruv Techumin that Chazal found important to institute. They only instituted Eruv Chatzeros (even when a Shitufei Mavo'os has already been made) in order that the concept of Eruv Chatzeros should not become forgotten from the children. Consequently, they were more lenient in connection with the leftovers of the Eruv.

6)

(a)The Gemara always rules like Rebbi Akiva, Rebbi Yossi and Rebbi, whenever they argue with a contemporary.

(b)

1. ... 'Matin' means - that we will inform an individual who comes to ask for a ruling that the Halachah is like Rebbi Yossi, but we will not announce this ruling in public.

2. ... 'Nir'in' means - that we will not even inform an individual of this ruling, but that, if someone does rule like him, we will not rescind that ruling.

(c)

1. The Halachah is not like Rebbi Meir, neither when he argues with Rebbi Yehudah nor when he argues with Rebbi Yossi.

2. When Rebbi Yehudah argues with Rebbi Yossi - the Halachah is like Rebbi Yossi.

(d)When Rebbi Shimon argues with Rebbi Yehudah, the Halachah is like Rebbi Yehudah - so how much more so when he argues with Rebbi Yossi.

7)

(a)The Gemara asks whose opinion we follow, when Rebbi Meir argues with Rebbi Shimon - and the She'eilah remains unresolved.

8)

(a)There is no proof for Rav Mesharshaya, who disagrees with the above principles (in 6) from the fact that Rav is quoted as ruling (in the Mishnah on 45b) like Rebbi Shimon, in spite of the fact that it is Rebbi Yehudah who argues with Rebbi Shimon - because it may well be that the rules only apply, when no other ruling has been issued, but it does deprive the Amora'im of the right to rule otherwise (Rebbi Yochanan's rulings come in to effect when no ruling was issued to the contrary.

9)

(a)An Ir shel Rabim ve'Na'asis shel Yachid - is a town whose residents (including guests) decreased from more than six hundred thousand Jews to less.

(b)One cannot make an Eruv to cover the whole town - because the main street is not considered a proper Reshus ha'Rabim, since it is not similar to the camp of Yisrael in the desert. Each Mavoy or area, must therefore arrange its own independent Eruv.

(c)Rebbi Shimon says that one does not require fifty residents to live outside the town, but three courtyards, each consisting of two houses, will suffice. The excess people living outside the town serve as a reminder that this is better than an Ir shel Yachid.

(d)The answer here (why we have no proof for Rav Mesharshaya) is as above in question 8 - i.e. because it may well be that the rules only apply when no other ruling has been issued, but not in face of a specific ruling.