Explanation: The Isur of Eshes Ach was uprooted. He can remarry her after he divorced her;

Just like the Isur was uprooted for him, it was uprooted regarding his brother born later, and she is [like] Eshes Achiv she'Hayah b'Olamo.

Implied question: The Mishnah did not mention the Tzarah!

Answer: It is included in "anyone forbidden [with] an Isur Ervah", which connotes that the Isur is due to Ervah, i.e. the Tzarah.

It did not need to mention the Tzarah explicitly, for it refers to the previous Perek.

Implied question: Why didn't we say that it comes to include Tzaras Sotah and Tzaras Machazir Gerushaso?

Answer: An Ailonis is more like Arayos, who were permitted to the Mes, and forbidden to do Yibum.

Question: Also from Nisu'in, we can ask why she does Chalitzah, since she cannot do Yibum!

An Aseh (Yibum) is not Docheh a Lav and an Aseh. She should be like Chayavei Kerisos!

Answer: Bi'Shlama (this is understood) applies only to "she does not do Yibum."

Question (Riva, in Sanhedrin 19a): Since a woman cannot become pregnant from the first Bi'ah, like it says below (34a), why may she do Yibum?

The first Bi'ah cannot [produce a child, to] continue the name [of the Mes], and the second Bi'ah is forbidden [mid'Oraisa], like we say below, that we decree [to forbid] the first Bi'ah due to the second Bi'ah!

Answer (Ri): We require only that the Yevamah and Yavam are proper to continue the name. We exclude only an Ailonis and Seris, who can never bear children;

We do not exclude a Bi'ah that cannot impregnate her, since in the end, she or the Yavam is proper to beget children.

Support: If not, you should ask how a minor Yevamah may do Yibum according to Chachamim. Also R. Meir would permit, if not for concern lest she be found to be an Ailonis!

Below (111b), a Mishnah says that if a minor [Yavam] had Bi'ah with an adult, she raises him [stays with him until he matures].

Also below (55b) we include that a Yevamah is acquired through Bi'ah Lo k'Darkah, or through Ha'ara'ah, even though she cannot become pregnant from it.

Explanation: Since they cannot do Yibum, they should not do Chalitzah.

Question #1 (Ri): How could we say that they do not do Chalitzah? "Yevimto", which teaches that they do not do Yibum, teaches [also] that they do Chalitzah!

We expound "there is another Yevamah who does Chalitzah"!

Question #2: Also, we ask Mah Ra'isa, i.e. I could say oppositely, and establish Yevimto for Chayavei Kares [to obligate Chalitzah], and "Im Lo Yachpotz" for Chayavei Lavin [to exempt from Chalitzah];

How could we learn from "Im Lo Yachpotz" to exclude Chayavei Lavin from Chalitzah? "Im Chafetz Yibem" applies to them, for Aseh Docheh Lo Sa'aseh [and there is no exclusion], since we establish Yevimto for Chayavei Kares!

Answer: The Gemara means "if so, also for Chayavei Lavin we should equate Chalitzah and Yibum from this verse" [and say that they do Chalitzah and Yibum]?

We further ask Mah Ra'isa, i.e. from this verse "Lo Yachpotz" why do you equate Chayavei Lavin for Chalitzah and Yibum, and say that they do Chalitzah and Yibum?

Implied question: Why do we need the verse? The Torah could have omitted it!

Answer: We need the verse for many matters, like I explained below (44a DH u'Neyabem l'Chada v'Nachlotzem l'Chada").

Question: If so, what was the answer "presumably, [since] Kidushin takes effect on Chayavei Lavin"? This answer connotes that we asked that they should not do Chalitzah!

Difficult Answer: We ask from Chayavei Lavin and Chayavei Aseh. We ask "if so, we should equate Chayavei Lavin and Chayavei Aseh for Chalitzah and Yibum from this verse;

Chayavei Lavin should do also Yibum, and Chayavei Aseh should not need even Chalitzah. The primary question is from Chayavei Aseh.

Question: What is the source to establish the verse to discuss Chayavei Lavin? We should establish it to discuss only Chayavei Aseh!

Even though they do not do Yibum, they do Chalitzah, since Kidushin Tofsin in them!

However, for Chayavei Lavin, we should say that Aseh Docheh Lo Sa'aseh, and they may do also Yibum!

Answer: Now he understands that we should expound Yevimto to forbid Yibum and obligate Chalitzah.

Question: If so, how could he think to establish the verse to discuss Chayavei Kerisos?

Suggestion: We ask that also Chayavei Kerisos should require Chalitzah from this verse.

Rejection: We say afterwards u'Mah Ra'isa, which implies that I could say oppositely [to discuss only Chayavei Kerisos. If Yevimto teaches also to forbid Yibum, it is unreasonable to establish it for Chayavei Kerisos, for we already expounded that they do not do Yibum!]

Explanation: Seris Adam excludes [Seris Chamah, which is] b'Yedei Shamayim, for he never was Kosher [to father children. Yibum does not apply to him at all.]

Implied question: This is permitted even l'Chatchilah. This is clear from below!

Answer: Since the Seifa used an expression of b'Di'eved, also the Reisha did.

Implied question: This Aseh (v'Hiskadashtem) applies also to the Mitzvah of Yibum, so Yibum is two Mitzvos Aseh!

Answer: Even so, two Mitzvos Aseh are not Docheh a Lav and an Aseh.

Explanation: These questions do not suggest that Chachamim totally uproot the Mitzvah of Yibum;

Rather, we asked that his paternal brother's wife should not do Yibum when he is only a paternal brother. We should decree to require a brother from the father and mother, due to a maternal brother.

A woman without children should not do Yibum, i.e. if now she does not have, but she had in her husband's lifetime, and they died. This is a decree due to a woman with children.

Eshes Achiv she'Hayah b'Olamo should not do Yibum, i.e. if he came from overseas and the Chazakah was that her husband has no brothers. This is like a brother who was not in the world [with the brother who died].

All women should not do Yibum, i.e. a woman who never had children, not from this husband and not from another man, for she resembles an Ailonis.

Note: Seemingly, there is reason to decree only when there it reason to suspect that she is sterile, e.g. she was married for many years without children. However, it is difficult to say that this is called "all women."

Explanation: A widow from Nisu'in, and Chayavei Aseh, we learn from Yevimto that even though they do not do Yibum, they do Chalitzah.

Explanation: "The second Bi'ah" is not precise. He may not even complete the first Bi'ah, since a Yevamah is acquired through Ha'ara'ah;

He could have said that we decree [to forbid Yibum] lest he complete the Bi'ah.

Question: We should permit a second Bi'ah, for she became his wife in every way!

Answer: She [fully] became his wife only when she is permitted without Dichuy;

For Chayavei Lavin, even though the first Bi'ah is permitted only because Aseh Docheh Lo Sa'aseh. Since there is no Aseh for a second Bi'ah, it is not Docheh.

Implied question: Below (61a), we require a verse only when he was Mekadesh, and afterwards he was appointed Kohen Gadol;

If he did Nisu'in before he was appointed, it seems that we do not need a verse that he may keep her, since he married her b'Heter!

Answer: Also there, it is because he married her b'Heter without overriding any Isur;

However, here, the first Bi'ah is permitted only because Aseh Docheh Lo Sa'aseh. A Bi'ah that is a Mitzvah is Docheh. A Bi'ah that is not a Mitzvah is not Docheh.

Question: Rava himself asked from this Beraisa, and now it refutes him!

Note: Aruch l'Ner - Rava can say that this Beraisa holds like Mishnah Rishonah, that Mitzvas Yibum has precedence, therefore one cannot fulfill both through Chalitzah. Rava explained the Mishnah like Mishnah Acharonah, that Chalitzah has precedence. One can fulfill both through Chalitzah, so there is no Dichuy. (However, the Gemara rejects this.) Rava properly refuted Rav Gidal, who learned from Yevimto that Yibum does not apply to Chayavei Lavin.