Learn the גמרא דף ג. “רב נחמן בר יצחק (sixteen lines from top of the Amud) until ורב נחמן בר יצחק (eighteen lines from top of the Amud)
Questions:
The gemara gives a new explanation of the reason for the Rabanan of קורה משום היכר
Where do we know the maximum width of the מבוי?
What is the reason for רבי יהודה who allows the korah to be placed above 20 Amos?
See פ’ מש ‘ לרמב”ם
https://hebrewbooks.org/pdfpager.aspx?req=14312&st=&pgnum=254
See “חידושי הר”ן דף ג “קורה
(see attachment)
And “ריטב”א “קורה
https://hebrewbooks.org/pdfpager.aspx?req=37287&st=&pgnum=4
And “גאו”י דף ג “רנב”י
https://hebrewbooks.org/pdfpager.aspx?req=14053&st=&pgnum=8
Learn the גמרא דף ג. “ורב נחמן בר יצחק (eighteen lines from top of the Amud) until מאי אמלתרא (last narrow line of the Amud)
Question:
Rabbah says the maximum height of the schach is 20 amos because any higher one will not notice the schach. The Gemara Sukkah says according to Rabbah when the walls of the sukkah extend until the Schach the schach can be placed higher than 20 amos as one will notice it.
According to this reason one should be permitted to place the קורה of a מבוי above 20 amos as the קורה rests on the walls of the מבוי?
Learn “ח’ ר”ן דף ג. “קורה
(see attachment)
And “רשב”א דף ג. “ומהא
https://hebrewbooks.org/pdfpager.aspx?req=37275&st=&pgnum=5
https://hebrewbooks.org/pdfpager.aspx?req=37275&st=&pgnum=6
Learn “תוס’ סוכה דף ב: “וכיון
https://hebrewbooks.org/shas.aspx?mesechta=7&daf=2b&format=pdf
https://images.shulcloud.com/13521/uploads/YNB-PTI/shiurim/rabbibodenheim/Ran3a–.pdf