Very quickly review the גמרא דף ה: “אמר רב חנן בר רבא (two dots on bottom of the Amud) until אמר רב נחמן בר יצחק ((nine lines from top of the Amud)
What is the case of קרו זוית?
Learn ריטב”א דף ו. “מאי שנא
https://hebrewbooks.org/pdfpager.aspx?req=37287&st=&pgnum=9
See ריף דף יא: מביא רב האי גאון
https://hebrewbooks.org/pdfpager.aspx?req=14312&st=&pgnum=329
and רמב”ם הלכות שבת פרק טז הלכה כ
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=71
Questions:
Are all doorways in corners not considered פתחים?
Learn “תוס’ ו. “דפתחא
Learn רמב”ם הלכות שבת פרק טז הלכה כ who disagrees with Tosfos
Tosfos brought a proof from the גמרא דף ה that explain the case of a Mavui with entrances from the chatzer in the corners. How does the Rambam explain that Gemara?
There are multiple explanations הגהה תוס’ ר פרץ אות 221
See ריטב”א בדף ה.
And הגהות רא”מ הורוויץ על תוס in the back of the Gemara
Questions:
What is the reason why רב הונא says the allowed size of a פירצה on side wall is only up to 4 Tefachim and not 10 Amos ?
Learn “תוס’ ו. “אחד (second half)
Why does this reason not apply to the front wall at the entrance to the Mavui?
Learn ריטב”א דף ו. “רב הונא אמר אחד זה
https://hebrewbooks.org/pdfpager.aspx?req=37287&st=&pgnum=9
According to the Ritva that רב הונא halacha applies even to the front wall at the entrance to the Mavui the reason Tosfos says for רב הונא does not apply.
What is the Ritva explanation of the opinion of רב הונא?
Continue learning the Gemara until the two dots (six lines from bottom of the Amud)
(Focus on the argument of רב חנן בר רבא and רב הונא for the size of פירצה on side wall – we will come back to the Sugya of מבוי עקום after we finish this topic)