1)

(a)The Mishnah now discusses a case where Reuven and Shimon married sisters Rachel and Le'ah) and Levi, a stranger (Dinah), and Reuven dies. Should Levi die after performing ...

1. ... Yibum with Rachel - both Dinah and Rachel are free to marry l'Shuk (the latter because she is Shimon's wife's sister, the former because she is her Tzarah).

2. ... Ma'amar with her - Dinah requires Chalitzah, whereas Rachel is free to marry l'Shuk.

(b)We can extrapolate from the Mishnah that if Levi did not even make Ma'amar with Rachel - then Shimon may even perform Yibum with Dinah.

(c)Rav Nachman learns from this Mishnah - 'Ein Zikah Afilu l'Chad Acha' ...

(d)... because otherwise, Dinah would be forbidden to Shimon (on account of Tzaras Achos Ishto b'Zikah) even if Levi had not even made Ma'amar with her.

2)

(a)Now the Mishnah discusses the above case, but where Levi died first. In the event that the latter died after having performed ...

1. ... Yibum with Dinah - both Dinah and Rachel are free to marry l'Shuk (the latter because she is his wife's sister, the former, because she is her Tzarah.

2. ... Ma'amar with her - then she requires Chalitzah, and Rachel is free to marry l'Shuk.

(b)In spite of the fact that the Ma'amar with his wife's sister forces the non-related wife to perform Chalitzah, and not Yibum (as we saw in the first Mishnah), the Tana repeats it in the second Mishnah, when it is the other way round (when he makes Ma'amar with the non-related wife, and it is his wife's sister who was married first) - because he really learned the latter Mishnah first, intending to permit the Tzarah in the earlier case. But then he changed his mind, deciding to forbid her too. He was so pleased with the Chidush however, that he learned it first.

(c)He did not scrap the second Mishnah, which is not teaching us anything new - because of the principle 'Mishnah Lo Zazah mi'M'komah' (The Tana'im opted to leave their Mishnayos intact).

3)

(a)Now the Mishnah discusses the same case as that in the first Mishnah (where Reuven and Shimon married sisters [Rachel and Le'ah] and Levi, a stranger [Dinah]), Reuven died and Levi performed Yibum with Rachel) only when Levi died after Le'ah. The Tana forbids Shimon to perform Yibum with Rachel - because, since she was once forbidden to him because of Achos Ishah (when Reuven died) she remains forbidden forever.

(b)Rav Yehudah Amar Rav rules that a Yevamah who is unable to perform Yibum when her husband dies - is like an Eishes Ach who has children (and will never become permitted).

(c)Even though we know this principle already from the Seifa of our Mishnah (' ... Ho'il v'Ne'esrah Sha'ah Achas'), we would have confined to to where she remains forbidden throughout the period of the first Nefilah - comes Rav Yehudah Amar Rav and teaches us that even if the source of the Isur falls way during that period, she becomes permitted.

(d)The Mishnah (later in the Perek) rules that, if Reuven and Shimon are married to two sisters, and first Reuven, and then Shimon's wife, die - Shimon is forbidden to perform Yibum with Reuven's wife, seeing as she was once forbidden to him ...

(e)... in which case, Rav Yehudah Amar Rav is coming to add - that even when there is a second Yavam, who is able to perform Yibum with the Yevamah, she nevertheless remains forbidden to the Yavam to whom she was initially forbidden, forever.

4)

(a)The Mishnah now discusses a case where Reuven and Shimon are married to two sisters (Rachel and Le'ah), and Levi to a Nochris (Dinah). Reuven divorces Rachel, and Levi dies. In the event that Reuven performs Yibum with Levi's wife and dies - the Tana declares that this is the case about which Chazal said 've'Chulan she'Meisu O Nisgarshu, Tzaroseihen Mutaros', and Reuven is permitted to perform Yibum with Dinah.

(b)Rav Ashi extrapolates from the sequence of events in our Mishnah - that had Reuven divorced his wife only after Levi died, then Levi's wife would have been forbidden to Reuven ...

(c)... a proof that this Tana holds - 'Yesh Zikah Afilu bi'Trei Achi'.

5)

(a)According to Rav Ashi, who just concluded that our Mishnah holds 'Yesh Zikah Afilu bi'Trei Achi', the Mishnah at the beginning of the Daf (from which Rav Nachman inferred [from the fact that the Tana requires Ma'amar on behalf of the Levi for the 'Nochris' to require Chalitzah from Shimon, and not Yibum] that 'Ein Zikah Afilu b'Chad Acha) inserts Ma'amar (not for the reason stated by Rav Nachman, but) - in order to preclude the opinion of Beis Shamai, who holds that Ma'amar is Koneh completely, in which case the 'Nochris' would not even require Chalitzah either.

(b)According to Rav Nachman (who holds 'Ein Zikah' and there is no difference whether Reuven divorced his wife first and then Levi died, or vice-versa) - the Tana says 'Zu Hi she'Amru ... ' to preclude when Shimon actually performed Yibum with Levi's wife before divorcing his own, in which case, she is forbidden to Reuven (like Rebbi Yirmeyahu, in whose opinion this Tana holds 'Nisu'in ha'Rishonim Mapilim').

(c)To reconcile that with Rava, who explained (in the first Perek) that both Mishnahs hold 'Misah Mapeles' and that the sequence of the Mishnahs is 'Zu, v'Ein Tzarich Lomar Zu'- we will have to establish Rav Nachman like Rebbi Yirmeyahu (who disagrees with Rava).

(d)And we are forced to say that Rava holds 'Yesh Zikah', like Rav Ashi - because since, in his opinion, both Mishnahs hold Misah Mapeles, our Tana cannot come to preclude when Reuven actually performed Yibum with Levi's wife before divorcing his own (like Rav Nachman), so it must come to preclude a case of when Reuven divorced his wife only after Levi died (from which Rav Ashi inferred above 'Yesh Zikah').

6)

(a)If the Ervah was a Safek Mekudeshes or a Safek Megureshes, says the Mishnah, the Tzarah requires Chalitzah and not Yibum. The case of Safek Kidushin is - where the man threw a document of Kidushin to a woman in the street and it landed exactly half-way at a distance of four Amos from each one.

(b)Safek Geirushin incorporates three cases: either her husband wrote her a hand-written Get without signed witnesses, or there were witnesses but the Get was undated - or the Get was dated, but was not written in the husband's handwriting and was signed by only one witness.

7)

(a)Rabah explains that the Tana does not explain Safek Megureshes in our Mishnah in the same way as Safek Mekudeshes ('Zarak Lah Gitah ... Safek Karov Lo Safek Karov Lei') - because in such a case, we would place the Tzarah on a Chezkas Heter l'Shuk (seeing as she was definitely a Tzaras Ervah, and a Safek would not remove that Chazakah).

(b)We do not apply the same principle to Safek Mekudeshes, and say that seeing as the Tzarah is b'Chezkas Heter l'Yavam, the Yavam is permitted to perform Yibum with her - because we go l'Chumra, and forbid Yibum.

(c)We initially think that this Chumra might lead to a Kula - because forbidding Yibum will lead us to presume that the Kidushin must have been effective. As a result, should he later betroth her sister, he will ignore the latter Kidushin and live with the first sister, or else someone else will betroth the first woman, and we will ignore that Kidushin, thinking that the first one's Kidushin was valid (whereas in fact, in both cases, both sets of Kidushin should be treated as a Safek Kidushin).

(d)The reason that we ignore the possible Kula, and apply the Chumra in spite of it, is - because the fact that he is required to perform Chalitzah will serve as a reminder that the Kidushin was not really valid and that she is only Safek Mekudeshes.