Learn the גמרא דף ב: “בין לרבנן until “ואכתי
Clarify the two possible ways to Rashi presents to read the gemara.
Questions:
Are we learning from the size of the opening of the Heichal/Ulam the maximum height and width of a מבוי or just one of them?
Learn תוס’ “בין
Conclusion for the position of the Rambam
See מגיד משנה הלכות שבת פרק יז הלכה א for an explanation of the Rambam
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=72
See ח’ גרי”ז עירובין for the Brisker Rav’s explanation of the Rambam
According to the Rashba, why does the fact that the fourth side of a מבוי is open to Karmilis or to a Reshus harabim impact whether the three walls of the מבוי can make this a Reshus Hayachid?