Daf Yomi: Pesachim 2a-3a: Reconstruction of the Original Sugya

In previous posts, I addressed the true meaning of Rav Huna and Rav Yehuda's statement about the definition of אור, showed how Mar Zutra's proof fit in to that end, and showed how a great many difficulties can be thusly resolved. What I would like to do it reconstruct the original sugya in the beginning of Pesachim, and explain what each statement means and how it fits in with the whole.

Reconstructing the original sugya is a fairly easy task in this instance. All that is involved is citing the statements by named Amoraim and omitting the rest, which is stamaitic.

The sugya I can reconstruct in this was is as follows:

דף ב, א משנה אור לארבעה עשר בודקין את החמץ לאור הנר כל מקום שאין מכניסין בו חמץ אין צריך בדיקה ובמה אמרו ב' שורות במרתף מקום שמכניסין בו חמץ בית שמאי אומרים ב' שורות על פני כל המרתף ובית הלל אומרים שתי שורות החיצונות שהן העליונות:

דף ב, א גמרא מאי אור רב הונא אמר נגהי ורב יהודה אמר לילי

דף ב, ב גמרא מיתיבי מר זוטרא

דף ג, א גמרא המפלת אור לשמונים ואחד בית שמאי פוטרין מקרבן ובית הלל מחייבים אמרו <להן> [להם] בית הלל לבית שמאי מאי שנא אור שמנים ואחד מיום שמנים ואחד אם שיוה לו לטומאה לא ישוה לו לקרבן

תני דבי שמואל לילי ארבעה עשר בודקין את החמץ לאור הנר

דף ד, א גמרא אמר רב נחמן בר יצחק בשעה שבני אדם מצויין בבתיהם ואור הנר יפה לבדיקה אמר אביי הילכך האי צורבא מרבנן לא לפתח בעידניה באורתא דתליסר דנגהי ארבסר דלמא משכא ליה שמעתיה ואתי לאימנועי ממצוה

Mishna:
The אור of the 14th we search for chametz by the light of a candle. Any place where we do not bring in chametz does not require searching. And regarding what did they discuss two rows in a wine-cellar? A place into which we bring chametz.
Bet Shammai say: Two rows over the entire cellar;
and Bet Hillel say:The two outer rows, that are the uppermost.

Gemara:
What is אור?
{We might think this is equal to its Aramaic cognate, אורתא, and thus means the late afternoon of the 13th, going into the 14th, and thus the Mishna states אור לארבעה .עשר}
Rav Huna said: Naghei.
And Rav Yehuda said: Leilei.
{Both agree, and are saying that אור means night and not late afternoon.}
Mar Zutra attempted to prove this {from the Mishna in Keritut 9b}: If a woman miscarries on the אור to the 81st. Bet Shammai exempt from a{n additional} korban and Bet Hillel require. Bet Hillel said to Bet Shammai: Why should the אור of the 81st differ from the day {=morning} of the 81st. If it is equivalent to it in terms of ritual impurity {that if she saw menstrual blood, she would be considered a niddah at this time}, should it not be equivalent to it in terms of korban?
{This proves that אור is night and not late afternoon, because late afternoon is still part of the 80th day and if she saw menstrual blood she would not be considered a niddah.}
Indeed - in the academy of Shmuel they taught {the Mishna as}: Leilei of the 14th we search for chametz by the light of a candle.
{Thus, it is clear that they regard אור to be leilei, which is not and not late afternoon. Now, why at night, and perhaps, why not earlier, in late afternoon?}
Rav Nachman bar Yitzchak said: At the hour that people are found in their houses and the light of the candle is good for searching.
Abaye said: Therefore a Torah scholar should not begin his seder of learning on the אורתא of the 13th which goes into the נגהי of the 14th lest his learning draw him in and he will then come to neglect the precept.

Perhaps rather than מיתיבי we should have something along the lines of תא שמע. Also, perhaps one can argue on my interpretation of Abaye's usage of אורתא, and thus manage to undermine this entire tower I have just built up. Comments welcome. :)

Stay tuned for a treatment of whether one may in fact do bittul on Pesach itself, and perhaps an analysis of Shamma Freidman's article on this issue, mentioned by mavami in a comment.