Very quickly review the גמרא דף יא עמוד ב from after the Mishna until the two dots.
Note the גירסא change of the הגהות הגר”א (side of the Gemara) from the ר”ח
What changes in conclusion of the gemara according to the גירסא change of the גר”א
Learn רמב”ם ה’ שבת פרק י”ד הלכה א
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=57
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=58
and פרק י”ז הלכה ט
https://hebrewbooks.org/pdfpager.aspx?req=14278&st=&pgnum=73
And השגת ראב”ד on side of the Rambam
Questions on the Rambam:
How many walls does the Rambam rule is required to create a Reshus Hayachid? (See מגיד משנה)
How could the Rambam seemingly rule contrary to the Gemara?
Learn the מגיד משנה for an answer.
Learn מאירי who also explains the Gemara similar to the Rambam’s ruling.
https://hebrewbooks.org/pdfpager.aspx?req=36399&st=&pgnum=23
Continue learning the גמרא דף יא: “ר’ אליעזר אומר (two dots – three lines from bottom of the Amud) until דף יב. “אמר רשב”ג (four lines from top of Amud)
Question:
Is ר’ אליעזר in accordance with ב”ש or ב”ה?
See רבינו יהונתן
https://hebrewbooks.org/pdfpager.aspx?req=14312&st=&pgnum=330
And ח’ ר”ן