Shabbat 100A

לאו היינו הנחתן. בעי רבא: אגוז בכלי וכלי צף על גבי מים ⁠— מהו? מי אמרינן בתר אגוז אזלינן, והא נייח, או דילמא בתר כלי אזלינן, והא לא נייח. תיקו.

it is not considered its placement. However, Rava raised a dilemma: In a case where there is a nut in a vessel and the vessel is floating on water, what is the ruling? Is it permitted to lift the nut on Shabbat if one is in another domain? The two sides of the dilemma are: Do we say that we go according to the status of the nut, and it is at rest in the vessel? Or perhaps we go according to the status of the vessel, and it is not at rest. No resolution was found to this dilemma. Therefore, let it stand unresolved as well.

שמן על גבי יין, מחלוקת רבי יוחנן בן נורי ורבנן. דתנן: שמן שצף על גבי יין, ונגע טבול יום בשמן ⁠— לא פסל אלא שמן. רבי יוחנן בן נורי אומר: שניהם חיבור זה לזה.

However, with regard to oil floating on wine, there is a dispute between R' Yoḥanan ben Nuri and the Rabbis. As we learned in a Mishnah: In the case of oil floating on wine, and one who immersed himself during the day, i.e., one who was impure, immersed himself in a mikveh, but will not become completely pure until sunset, touched the oil, he invalidated only the oil and not the wine. R' Yoḥanan ben Nuri says: With regard to the two, i.e., the oil and the wine, they are considered to have a connection to each other. Since he made the oil impure, the wine is also impure. Their dispute is whether or not the oil is considered to be placed atop the wine.

אמר אביי: בור ברשות הרבים עמוקה עשרה ורחבה שמנה, וזרק לתוכה מחצלת ⁠— חייב. חילקה במחצלת ⁠— פטור. לאביי דפשיטא ליה דמחצלת מבטלא מחיצתא ⁠— כל שכן חוליא דמבטלא מחיצתא. לרבי יוחנן דמיבעיא ליה חוליא, מחצלת פשיטא דלא מבטלא מחיצתא.

Abaye said: In the case of a pit in the public domain that is 10 handbreadths deep and precisely 8 handbreadths wide, and one threw a mat into it, he is liable. However, if he divided the pit with a mat that split it in two, each one slightly less than 4 handbreadths wide, he is exempt because neither part is considered a private domain. The Talmud comments: According to the opinion of Abaye, for whom it is obvious that the mat eliminates the partition of the pit, all the more so that a segment of dirt thrown into a pit that is 10 handbreadths deep, rendering it less than 10 handbreadths, eliminates the partition, and he has no dilemma with regard to R' Yoḥanan’s case. According to R' Yoḥanan, who raised a dilemma with regard to a segment of dirt, it is obvious that a mat does not eliminate the partition.