Beitza 10a.

1- Mishna discusses the process of identifying fowl (on erev Yom Tov) that one will use on Yom Tov. Bais Shamai’s opinion is that one must pick up and shake the actual bird(s) and thereby remove their ‘muktze’ status. [shake before you bake…]

Beis Hillel permits one to designate the birds for use on Yom Tov merely by naming them verbally.

2- Our Gemara discusses the requirement of Bais Hillel in identifying the actual bird one plans to shecht. It is insufficient to merely generally state “I will take some of these birds” and then choose the actual ones on Yom Tov.

The Gemara delves into the concept of Breira. Meaning, subsequent decisions can under certain circumstances be retroactively applied to change or clarify the nature and Jewish-law consequences of prior events.

If follows that if Breira would apply here one would be allowed to merely ‘choose a group of birds’ and on Yom Tov itself select individual ones. This selection would retroactively be considered to have taken place prior to Yom Tov.

3- The case of Breira quoted by our Gemara concerning ‘sof ha’tumah lotzeis’. The path of a deceased body on the way to burial is considered ‘tamei’ rendering all overhead rooms, halls, arches and doors to be tamei. If Breira applies here then by choosing a particular path after the person has dies this choice is valid retroactively and all other paths are tahor.

4- We mentioned the story of the sefer Ohr Hameir by Reb Meir Shapiro. Reb Meir having attended the Rebbe’s wedding gave the Rebbe a copy of his book as a wedding gift . See here page 367 (376)  http://www.chabadlibrary.org/books/pdf/mbhg-h.pdf for the inscription.

The Rebbe once quoted this sefer at a Farbreingen in 1971.

5- The first teshuva in this sefer concerns a tragic accident in an attic of a shul where a grinding machine(?)  chewed off the arm of its user causing a partial collapse to the attic etc.

The question was if Kohanim were to be allowed into this shul least the severed arm is still intact under the rubble rendering the entire shul as tamei. He points out that even if the attic is a separate entity and the arm in the attic has no effect on the main beis medrash nevertheless the path the arm will follow to its burial will pass through the shul!

6- We spoke about the halacha quoted by the Rama in the name of the Trumas Hadashen (previous shiur regarding chickens laying an egg bein hasmashos…) that prohibits Kohanim from traveling on a bridge where a funeral will be passing. The concept of ‘sof ha’tumah lotzeis’ creates a tumah under every door, gate, arch or bridge that is in the path of the planned funeral route.

7- We mentioned a case of a family that wanted to delay a funeral of a deceased family member and kept the body in their apartment (as opposed to storing it in a funeral home). The issue is that all the kohanim in that complex would basically become homeless until the funeral procession.

Can the neighbors protest? See here. End of sk4.