Resources for Nedarim 48

The משנה says that if two people are מודר הנאה from each other, then they cant enter their local shul since they both are partial שותפין in it. The ר"ן points out that our משנה must not be אליבא דהילכתא since we pasken like רבי אלעזר בן יעקב who says that when two people are מודר הנאה from each other from each other they can still walk into a shared property since we say יש ברירה (as long as its אין בו דין חלוקה ) and each one can say I’m just walking in to my portion. Here too, each one should be able to go into shul with and say they are only using their portion as a shul is also אין בו דין חלוקה as the גמרא said earlier on דף מ"ו ע"ב. The issue is that the רמב"ם in הלכות נדרים פרק ז הל׳ ד paskens like ראב"י that each one can say they are walking into their portion and yet also paskens like our משנה that says they both cant walk into shul. How can both be true? The רמב"ן asks this question as well. While the ר"ן only asks on the רמב"ם , the רא"ש and טור, and pasken like the רמב"ם as well. The שולחן ערוך as well in סימן רכ"ד paskens this way. So how do we explain all these poskim seemingly to be in a סתירה? The ב"ח, תוספות יו"ט and גר"א all give the same answer: the רא"ש explains that the reason we don’t say יש ברירה if its יש בו דין חלוקה is we shouldn’t be סומך on ברירה if we can get out of it. Here too, the person can simply write their portion of the shul to the נשיא and therefore we should not use ברירה. By a normal field which is אין בו דין חלוקה we will allow ברירה since writing his חלק to the נשיא would be an obvious הערמה since he would still continue to use it. By a shul, there is no הערמה since everyone can use the shul. Once we say this, our משנה which is a סתם משנה would be the correct פּסקwhich is why the רמב"ם decided this must be the correct פּשט. However, the ט"ז in סימן רכ"ד ס"ק אthinks this cannot be because it means ignoring what רב יוסף said on דף מ"ו since רב יוסף said there that our משנהis a case of אין בו דין חלוקה where ברירה would apply, and no one argues on him. (Also, if רב יוסף was wrong then רבה is right and ברירה would apply in all cases and no one paskens that.) Rather, the ט"ז suggests that you need to be מדייק in the גמרא that says a shul is “like” something that has no דין חלוקה, but not quite at that level. In fact, there are three levels: a regular large field is real יש בו דין חלוקה and is easy to split. A tiny field less than 4x4 אמות is a full אין בו דין חלוקה. The mid level is a shul which is not quite either. רבהon דף מ"וwas talking about a real יש בו דין חלוקה, but something like a shul is called אין בו דין הלוקה and מותר according to all. רב יוסף says that’s not possible because then our משנה is like no one. Rather, רב יוסף goes on to talk about a real אין בו דין חלוקה, but is מודה that a shul is like a יש בו דין חלוקה. This way there is no סתירה.