An important point in this Gemara appears to be that there was a close relationship between Rav Chisda and Rabah bar Rav Huna and due to a challenge from Rav Chisda (not the other way round, as you wrote that Rabah bar Huna asked a question on Rav Chisda and Rav Chisda qualified his position) Rabah bar Rav Huna retracted, and made a point of retracting in public (see also the Gemara below 86b and Rashi DH Chavereinu where Rabah bar Rav Huna called Rav Chisda 'our friend who is expert in Halacha'; which shows us the respect in which Rabah bar Rav Huna held Rav Chisda). Rav Chisda was the Rosh Yeshiva first in Sura, and then when he died Raba bar Rav Huna became the Rosh Yeshiva in his place.

In contrast we do not see that there was a debate between Rav Chisda and Rava in this particular Halacha (even though Rava was in fact the son-in-law of Rav Chisda; see Kesuvos 65a and Rashi DH Tavah ) so we do not have any evidence that Rava retracted (in addition there is a text here that reads Rabah instead of Rava - see Oz v'Hadar).

I saw in the Rosh here, that he does not cite Rava at all, but starts the sugya with Rabah bar Rav Huna's original statement, and then cites Rav Chisda's challenge and Rabah bar Rav Huna's revision. He then cites Rav Sheshes who disagrees wth Rabah bar Rav Huna and Rav Chisda but paskens like Rav Chisda. The Rosh does not write that Rava together with Rav Sheshes makes it 2 against 2. It is possible that the Rosh did not even have any mention of Rava in his text of the Gemara.

There is another strange thing in this sugya; namely that Rava, who was the latest chronologically, is mentioned first. [ Rava was the son of Rav Yosef bar Chama - see Eruvin 44a and Nedarim 55a - and Rav Yosef bar Chama was a student of Rav Sheshes - see Gitin 14a, near the end of the page; and see Shabbos 63a; and Rava was the son-in-law of Rav Chisda - see Kesuvos 65a and Rashi DH Tavah l'Bas; whilst Rabah bar Rav huna was more senior than Rava as he was the friend of Rav Chisda, as we saw above in the name of Gitin 86b].

A short thought:-

I just noticed that there is a simple answer to what I asked above; why does Rava, who is the latest chronologically; come first in the Gemara? The answer is that since the Gemara jsut cited Rava saying "Rayoi Litol v'Ein Lo" the Gemara then reported first what Rava said about the next issue.

Dovid Bloom

The Gra also does not seem to have Rava in his text:

I saw, bs'd, in Biur HaGra to Shulchan Aruch Even Ha'Ezer 44:21, that he writes that the Rosh, Tur and Shulchan Aruch paskened like Rabah bar Rav Huna and Rav Chisda; against Rav Sheshes; because Rav Sheshes is a lone opinion against Raba bar Rav Huna and Rav Chisda. One sees from the Gra that in his girsa in the Gemara Rava was not mentioned, since if Rava would have been mentioned, the Gra could not have said that Rav Sheshes is on his own since he had Rava on his side. I also saw in the Beis Yosef, on Tur 44:12, that when he cites the Gemara he does not mention the words of Rava at all, in the same way that the Rosh did not mention them.

Dovid Bloom

The explanation of Rabbi Emanuel Chai Riki Hy'D:-

1) I found a beautiful explanation of the sugya in the sefer Aderet Eliyahu on Maseches Gitin by Rav Refael Emanuel Chai Riki (1688-1743) of Italy and Eretz Yisrael, to Gitin 43a page 105 DH Hamekadesh. He starts by pointing out the difference in the wording between what Rava said that "Hamekadesh" half a woman is not "Mekudeshet" and what he said that a lady, who is half Shifchah and half free, who was "Nitkadshah". Why does Rava use the word Hamekadesh [ an active form] in one case, whilst on the second occasion he uses the word Nitkadshah [ a passive form]?!

2) He answers that there is a difference between someone who marries a free woman, and someone who marries a Shifchah. The Gemara Kidushin 2b tells us that Adam HaRishon lost his rib to Chava, and a person who lost his belongings must go round searching for them. This is why a man goes looking for his wife. A Shifchah is different. The Gemara says above 38a (see Rashi DH Mitzali) that people look upon a Shifchah cheaply, so she has to attract her husband to marry her. This is why Rava and Raba bar Rav Huna used the word Hamekadesh in connection with a standard kidushin because it was initiated by the man, and the word Nitkadshah in connection with the half Shifchah, because the kidushin was initiated by the woman. And this is why Rava said "her kidushin are not kidushin" because they are called her kidushin since she tried to initiate them. But Rabah bar Rav Huna made a mistake the first time he said his Halacha. He said "Einah Mekudeshet" which suggests that if it would have been a kidushin it would have been a standard kidushin effected by the man, but this is not true in the case of a Shifchah. This is why Rabah bar Rav Huna had to retract.

3) Aderet Eliyahu page 106 DH uBeZeh writes that we can now understand why Rav Chisda only asked on Raba bar Rav Huna, not on Rava. Rava said her "kidushin are not kidushin" which suggests thst she does possess some kind of kidushin but they are not complete kidushin. In contrast Raba bar Rav Huna said the first time that "Einah Mekudeshet" which suggests that there is no kidushin at all. So according to Rava if someone else had biyah with her after such kidushin he would receive Malkus and would have to bring a korban Asham, whilst according to Rabah bar Rav Huna she is not mekudeshet at all, and no issur would be involved. This is why Rav Chida only asked on Raba bar Rav Huna, because Rava agrees that some aspect of kidushin is effectively achieved.

4) And see Tosfos 43b DH Mah that Rabah bar Rav Huna retracted, which suggests that Rava did not retract.

Dovid Bloom

The use of the phrase "Kidusheha Kidushin" and the word "Margilaso":-

1) The Aderet Eliyahu, that I cited above, explained the phrase "Kidusheha Kidushin" that was used by Rava here, and we can now show from other places in Shas, bs'd, that his explanation is consistent. There is a Mishnah Kidushin top 79a about a woman who gave permssion to a Shaliach to be Mekadesh her, and then went and did Kidushin for herself. The Mishnah states that if her Kidushin came first then "Kidusheha Kidushin". This fits in with the rule of Aderet Eliyahu that if she initiated the Kidushin then the phrase Kidusheha Kidushin is used (however it is not such a strong source since the Mishnah there states that if the kidushin of the shaliach came first then "Kidushav Kidushin" so one would can argue that Kidusheha Kidushin is used in contrast to the phrase Kidushav Kidushin). However there is another source in Kidushin 44b which discusses a minor girl who was Nitkadsha without the knowledge of her father. Rashi DH Ketana writes that everyone agrees that "Ein Kidusheha Kidushin" instead of using the more widespread phrase of "Einah Mekudeshet".

2) We can also find sources in Shas for what I translated above as the "Shifchah has to attract her husband to marry her". The Hebrew word for this is "Margilaso". We find this word used in Yevamos 85b. Rashi there DH Ha Hi Margela writes that she makes a Tircha and goes round to marry a Yisrael. What Rashi writes seems to be contradicted by Gemara Kidushin 2b that the man looks for the woman but one has to say that since Yevamos 85b refers to a Mamzeres she possesses special motivation to improve her offspring, as Rashi writes there. So in a case where she makes a special effort to marry him the phrase Kidusheha Kidushin or Ein Kidusheha Kidushin is appropriate, as used by Rava and Rav Sheshes in our Gemara.

Dovid Bloom