ואע"ג דבטלינהו [לכולהו] משום דבטלה דעתו אצל כל אדם
And even though he nullified them all, intending that for the duration of the Festival the halakhic status of these cushions and blankets is nothing more than that of dirt, it is not deemed a fit nullification because his intention is rendered irrelevant by the opinions of all other people. People do not typically do so, so the action of one who does so is discounted.
תבן ובטלו הוי מיעוט וכל שכן עפר ובטלו
If one placed straw on the floor of his sukka in order to diminish its height, and verbally nullified it by saying that he will not use it for another purpose, it is a decrease of halakhic significance, as the halakhic status of adding straw is like that of adding dirt to the sukka floor and diminishing its height. The same is true, all the more so, if he placed dirt on the sukka floor and nullified it.
תבן ואין עתיד לפנותו ועפר סתם מחלוקת ר' יוסי ורבנן דתנן בית שמילאהו תבן או צרורות וביטלו מבוטל
A case where one placed straw on the sukka floor and he does not intend to evacuate it from there, although he did not nullify it, and a case where one placed undesignated dirt that was not nullified, are the subject of a dispute between Rabbi Yosei and the Rabbis with regard to whether the actions alone are effective as nullification. As we learned in a mishna: In a house in which there is a corpse or an olive-bulk of a corpse, the halakha is that if there is a handbreadth of space between the corpse and the roof, the roof serves as a barrier that prevents the ritual impurity from spreading beyond the roof. However, if there is less than a handbreadth of space between the corpse and the roof, the roof does not serve as a barrier, and the ritual impurity spreads upward. In a house of that sort where one filled the space between the corpse and the roof with straw or pebbles mixed with clods of dirt, and then nullified the straw or dirt, it is effectively nullified, and the ritual impurity spreads upward.
ביטלו אין לא ביטלו לא ותני עלה רבי יוסי אומר תבן ואין עתיד לפנותו הרי הוא כעפר סתם ובטל עפר ועתיד לפנותו הרי הוא כסתם תבן ולא בטיל
By inference, if he explicitly nullified it, yes, it is nullified; if he did not nullify it, no, it is not nullified. And it is taught concerning this mishna in the Tosefta that Rabbi Yosei says: If one placed straw on the sukka floor and he does not intend to evacuate it, its halakhic status is like that of undesignated dirt and it is nullified. If he placed dirt on the sukka floor and he does intend to evacuate it, its halakhic status is like that of undesignated straw, and it is not nullified. Apparently, the tanna’im already discussed this matter.
היתה גבוהה מעשרים אמה והוצין יורדין בתוך כ' אמה אם צלתם מרובה מחמתם כשרה ואם לאו פסולה
If a sukka was more than twenty cubits high, but the ends of the palm leaves [hutzin] fall within twenty cubits, then the following distinction applies: If the shade provided solely by the leaves within twenty cubits of the ground is greater than the sunlight in the sukka, it is fit. If not, it is unfit.
היתה גבוהה י' טפחים והוצין יורדין לתוך י' סבר אביי למימר אם חמתם מרובה מצלתם כשירה
The Gemara applies the same principle to the opposite case. In a case where the sukka was only ten handbreadths high, the minimum height for a fit sukka, but the ends of the palm leaves fall within ten handbreadths, Abaye thought to say that the same calculation applies here: If the sunlight in the sukka is greater than the shade provided by the leaves within ten handbreadths of the ground, meaning that those leaves do not constitute a fit sukka on their own, the sukka is fit.
א"ל רבא הא דירה סרוחה היא ואין אדם דר בדירה סרוחה
Rava said to him: That calculation does not apply in this particular case, as, if the branches fall within ten handbreadths of the ground, that is considered a sagging [seruḥa] residence, and a person does not reside in a sagging residence. Therefore, it cannot even be considered a temporary residence.
היתה גבוהה מעשרים אמה ובנה בה איצטבא כנגד דופן האמצעי על פני כולה ויש בה הכשר סוכה כשרה
If a sukka was more than twenty cubits high and one built a raised platform in it opposite the entire middle wall, as typically a sukka has three walls and the fourth side is open as an entrance, and the platform has an area of at least a bit more than seven by seven handbreadths, the minimum area required for fitness of a sukka, the sukka is fit. Since the seven-by-seven-handbreadth section from the platform to the roof has three walls and it is less than twenty cubits high, that section is a fit sukka in and of itself, and the rest of the sukka beyond the platform is fit as far as the roofing continues.
ומן הצד אם יש משפת איצטבא לכותל ד"א פסולה פחות מארבע אמות כשרה
And if one built the platform along the side wall of the sukka, then the following distinction applies: If there are four or more cubits from the edge of the platform to the opposite wall, the sukka is unfit, as the area of the platform has only two walls. However, if the distance to the opposite wall is less than four cubits, the sukka is fit, as the halakhic status of the roofing that covers the distance to the wall is that of a curved extension of the opposite wall.
מאי קא משמע לן דאמרינן דופן עקומה תנינא בית שנפחת וסיכך על גביו אם יש מן הכותל לסיכוך ד"א פסולה הא פחות מכאן כשרה
The Gemara asks: What is this halakha teaching us? Is it that we say that the halakha of a curved wall applies to the halakhot of sukka? We already learned this halakha in a mishna (17a): In the case of a house that was breached by a hole in the middle of the roof, and one roofed over the breach, if from the wall to the roofing there are four or more cubits of the remaining original roof it is an unfit sukka. By inference, if the distance is less than that, it is a fit sukka. That is due to the halakha of a curved wall. The intact portion of the roof is considered an extension of the wall. As this halakha was already taught with regard to sukka, what is novel in the halakha of the platform?
מהו דתימא התם הוא דחזיא לדופן אבל הכא דלא חזיא לדופן אימא לא קמ"ל
The Gemara explains that there is indeed a novel element to the halakha of the platform. Lest you say that that one applies the halakha of a curved wall specifically there, in the case of a house that was breached, as the wall of the house is suited to be the wall of a sukka since it is less than twenty cubits high; however, here, in the case of the platform, where the opposite wall is not suited to be the wall of a sukka due to its excessive height, say no, the halakha of a curved wall does not apply. Therefore, it teaches us that in the case of the platform too, the roof is considered an extension of the wall.
היתה גבוהה מכ' אמה ובנה איצטבא באמצעיתה אם יש משפת איצטבא ולדופן ארבע אמות לכל רוח ורוח פסולה פחות מארבע אמות כשרה
If the sukka was more than twenty cubits high and one built a platform in the center of the sukka if there is from the edge of the platform to the wall in each and every direction a distance of four cubits, it is unfit, as the platform has no walls. If the distance is less than four cubits, then it is fit.
מאי קא משמע לן דאמרינן דופן עקומה היינו הך
The Gemara asks: What is this halakha teaching us? Is it that we say that the halakha of curved wall applies to the halakhot of sukka? Then this halakha is identical to that halakha, as we already learned that the halakha of a curved wall applies.
מהו דתימא דופן עקומה מרוח אחת אמרינן אבל כל רוח ורוח לא קא משמע לן
The Gemara explains that there is indeed a novel element to the halakha. Lest you say that we say that the halakha of a curved wall applies only in one direction, with regard to one wall of the sukka; but in each and every direction with regard to all the walls of the sukka, no, the halakha does not apply; therefore, it teaches us that this halakha may be applied to consider the roof as an extension of all four walls.
היתה פחותה מי' טפחים וחקק בה כדי להשלימה לעשרה אם יש משפת חקק ולכותל ג' טפחים פסולה
If the sukka was less than ten handbreadths high and he dug out an area inside the sukka in order to complete the requisite height of the sukka to ten handbreadths, if from the edge of the dug-out area to the wall there is a distance of three handbreadths, it is unfit, as in that case the edge of the dug-out area is not joined to the wall of the sukka. Therefore, even though the interior space is ten handbreadths high, its walls are not the requisite height to be considered a fit sukka.