1. The Gemara explains why we are permitted to benefit from Chametz owned by a Nochri on Pesach.
2. There is a dispute about whether someone who eats Chametz that belongs to Hekdesh on Pesach transgress Me'ilah.
3. Rav: Chametz does not become nullified on Pesach.
4. Rav and Shmuel generally differentiate between forbidden mixtures of the same type and mixtures of a different type.
5. Rebbi Yochanan and Reish Lakish do not distinguish between these two types of mixtures (#4).
A BIT MORE
1. This is derived from the verse, "It should not be seen by you," implying that one may not have Chametz in his possession, but after Pesach one may benefit from Chametz that a Nochri owned on Pesach.
2. Rebbi Nechunyah ben ha'Kanah says that one does not transgress Me'ilah (due to the concept of "Kim Lei bed'Rabah Minei").
3. Accordingly, on Pesach, even if a small amount of Chametz falls into a mixture, the entire mixture is forbidden.
4. If the forbidden item is mixed together with the same type of item that is permitted, then the mixture is forbidden. If it is mixed with a different type of item, then only when the taste of the forbidden item is apparent in the mixture (usually this is at least one in sixty parts) do we say that the mixture is forbidden.
5. They maintain that whether it is of the same type or a different type, it depends on whether it adds taste to the mixture.