erev yom kipur 5759,
gmar hatima tova
Question: neemar babraita sior yessaref venotno lekalbo ....
(aliba derav yehuda kaamar veassior derav meir)
lama neemar notno lekalbo, sheyiheye mutar lo leekol??
[Translation: The Beraisa states that "Se'or (bread that has not leavened completely) must be burned (one may not derive any benefit from it), and one may give it to his dog (one may derive benefit from it)...." The Gemara resolves the contradiction by saying that the first statement means that Se'or -- as defined by Rebbi Yehudah -- must be burned according to Rebbi Yehudah, and as defined by Rebbi Meir must be burned according to Rebbi Meir. The second statement, which implies that one may derive benefit from it, is describing what Rebbi Yehudah would say about the Se'or as defined by Rebbi Meir.
However, Rashi explains that Rebbi Meir's Se'or is -- according to Rebbi Yehudah -- Matzah! If so, why does the Beraisa say that Rebbi Yehudah says that one should give it to his dog? He should say that it is Mutar for a person to eat!]
TOSFOS (DH v'Nosno) mityaches l'she'eilatcha v'omer she'b'emet, l'fi Rebbi Yehudah, Mutar Min ha'Torah Le'echol ha'Se'or Shel Rebbi Meir, Ela she'ha'Rabanan Asru le'Ochlo, v'Rak Hitiro b'Hana'ah.
[Translation: Good question. TOSFOS (DH v'Nosno) answers that indeed, mid'Oraisa Rebbi Yehudah holds that it is Mutar to eat Rebbi Meir's Se'or. The Rabanan, though, prohibited it, seemingly because it does resemble Chametz in some way.]