(Mishnah): These exempt their Tzaros, and the Tzaros of their Tzaros, [and the Tzaros Tzaros of her Tzaros....] from Chalitzah or Yibum ad infinitum;

If any of these died, did Mi'un (annulled a mid'Rabanan marriage), was divorced, or was found to be an Ailonis (a girl who does not develop like a normal female), the Tzaros are permitted (i.e. obligated to do Yibum or Chalitzah with Shimon or another brother).

Mi'un and being found to be an Ailonis do not apply to the mother and grandmothers of Shimon's wife. (Mi'un must be before adulthood, and a minor cannot gave birth. An Ailonis is sterile.)

(Gemara - R. Yochanan): She can do Mi'un to her Yavam to uproot Zikah of the Mes, to permit the Tzarah to her father (i.e. if she fell to Yibum to her father; without Mi'un, the Tzarah is forbidden due to Tzaras Ervah) and [even when she is not Ervah to the Yavam, permit] a daughter-in-law (herself) to her father-in-law.

(Rav and Reish Lakish): She cannot do Mi'un to her Yavam to uproot Zikah of the Mes, to permit the Tzarah to her father and a daughter-in-law to her father-in-law.

Question: Do Rav and Reish Lakish hold like Beis Shamai?! Beis Shamai say that [she cannot do Mi'un to her Yavam, only] to her husband!

Answer - Question: What is the case?

If she says 'I do not desire marriage to you and not the marriage to your [dead] brother', all agree that she uproots!

If she says [to the Yavam] 'I do not desire marriage to you, but I desire the marriage to your brother', all agree that she does not uproot! (SHA'AREI TORAS ERETZ YISRAEL, with a small addition.)

Answer: Rather, the case is, she says [Stam] 'I do not desire marriage';

R. Yochanan says, it is as if she says 'I do not desire marriage to you and not the marriage to your brother';

Rav and Reish Lakish say, it is as if she says 'I do not desire marriage to you, but I desire the marriage to your brother';

Question #1: [Our] Mishnah argues with R. Yochanan! If any of these died, did Mi'un, was divorced, or was found to be an Ailonis, the Tzaros are permitted. Is divorce not from him (her husband? Surely it is!) Likewise, 'did Mi'un' is from him (her husband, and not to the Yavam)!

Question #2: R. Chiyah taught so (unlike R. Yochanan). If they did Mi'un or were divorced in the husband's lifetime, the Tzaros are permitted. [If they did Mi'un] after the husband died, the Tzaros do Chalitzah and not Yibum.

Answer #1 (R. Yudan, the father of R. Matanyah): The case is, [the widows] died and did not do Mi'un. The Beraisa means that anyone who could have done Mi'un, but did not do Mi'un, her Tzarah does Chalitzah and not Yibum.

So we must explain Mishnah (#4, below). Anyone who could have done Mi'un, but did not do Mi'un, and she died, her Tzarah does Chalitzah and not Yibum.

Answer #2 (R. Aba Mari): You can even say that [in the Mishnah and Beraisa] she is alive. The case is, the only Yavam is her father. (Then, Mi'un to the Yavam does not help, for at the time she fell, the Tzarah looked like Tzaras Ervah.)

(R. Yonah): (If she was found to be an Ailonis, the Tzarah is permitted.) This is only from Eirusin (presumably, the Kidushin was mistaken and invalid. However, if she was Nesu'ah, the Tzarah is forbidden.)

(R. Yosah): It is even from Nisu'in.

The next time he learned [Yevamos], R. Yosah retracted [to say like R. Yonah]

R. Pinchas: Did Rebbi (you) not teach us [even] from Nisu'in?!

R. Yosah: Is it fixed for you like a nail [that I cannot retract]?!

Question (R. Ze'orah, to R. Mana): (Why did R. Pinchas object?) Did R. Yosah say properly before he retracted?! If Bito from Nisu'in was not an Ailonis, her Tzarah is forbidden. Because there is added [another reason to forbid Yibum, i.e. she is an] Ailonis, is her Tzarah permitted?! (We explained this like PNEI MOSHE.)

Answer (R. Mana): An Ailonis, it is as if she is not in the world (i.e. she was never married);

If there are two Yevamos - one is an Ailonis and one is not an Ailonis, and the Yavam did Chalitzah to [the Ailonis] or had Bi'ah with her, does it exempt her Tzarah at all?!

Inference: An Ailonis, it is as if she is not in the world.