1)

(a)According to Shmuel citing Levi, the third (Tefach) wall should be placed at ninety degrees to one of the other two walls (like Rav) - and that is what they feel inclined to say in the Beis-Hamedrash.

(b)Rebbi Simon (or Rebbi Yehoshua ben Levi) says - that the third wall, which is compressed, must be placed within three Tefachim of one of the two regular walls.

(c)If a regular Tefach comprises four Etzba'os which touch whilst measuring, a Tefach Shochek is measured - with fingers not touching, to create a slightly larger Tefach than usual.

(d)The Tefach-wall is placed within three Tefachim of one of the existing walls, which (by means of 'Lavud') constitutes the majority of a seven-Tefachim wall.

2)

(a)According to Rav Yehudah, the same ruling of a third Tefach-wall will apply if one has two existing walls that are (not adjacent, but) parallel, which one then places in exactly the same way as in the previous case - i.e. within three Tefachim of any of the four corners.

(b)Rebbi Simon (or Rebbi Yehoshua ben Levi) disagrees. According to him - the third must comprise a board of at least four Tefachim, which one then places within three Tefachim of any of the corners (making a complete third wall - by means of 'Lavud', and not just the majority of it).

(c)In his opinion, the Din by parallel walls is more stringent than by adjacent ones - because, unlike them, they do not actually form part of a constructed Sukah (only two independent walls).

3)

(a)Besides the requirement that we discussed until Now, Rava also requires a Tzuras ha'Pesach - i.e. two side-posts with a cross-bar on top.

(b)According to the first interpretation - the Tzuras ha'Pesach replaces the Tefach post of which we spoke earlier - stretching across the entire length of the third wall. This entails placing one half-Tefach post adjacent to the corner, and another similar post at the far end of that side (with nothing in the middle), with a cane running across the top from one post to the other.

(c)The second interpretation of Rava's undisputed opinion maintains that the Tzuras ha'Pesach does not replace the Tefach-post, but is an alternative method of building the third wall; and the third interpretation is - that both are needed, the Tefach post, and a Tzuras ha'Pesach, stretching from it to a post that is placed at the far end.

(d)Rav Ashi holds like the second explanation - Rav Kahana, like the third.

(e)The Halachah - is like Rav Kahana.

4)

(a)Rabah says that the validity of the third Tefach-wall applies to Shabbos, too - with regard to a Sukah that adjoins one's house. This is on account of the principle of 'Migo' (since) the wall is Kasher with regard to Sukah, it is also Kasher with regard to Shabbos, and is therefore considered a Reshus ha'Yachid, permitting carrying from the Sukah to the house.

(b)The 'Migo' only applies to the Shabbos during Sukos, but not to the rest of the year.

5)

(a)The Beraisa says that the walls of ...

1. ... a Sukah have the same leniencies as those of Shabbos - with regard to a wall that is made of vertical or horizontal posts (which do not have a space of three Tefachim between one post and the next - and which is Kasher (despite the fact that the spaces exceed the actual wall) due to the principle of 'Lavud'.

2. ... a Sukah has leniencies that the wall of Shabbos do not - inasmuch as a Sukah is permitted even if it has large spaces (e.g. doorways - not to speak of our case, where the best part of two whole walls are missing) that are larger than the built-up wall, whereas on Shabbos, they would be invalid.

(b)Abaye poses a Kashya on Rabah's previous ruling from there - as the Beraisa does not appear to hold of 'Migo'.

(c)If, as we explain, the Beraisa is talking about Shabbos throughout the year (but not on Sukos) - then the Beraisa ought to have added that Sukah, too, has a Chumra over Shabbos, inasmuch as the third wall of a Sukah (that has two parallel walls) must be at least one Tefach wide, as we learned above (according to Rav Yehudah); whereas on Shabbos, this is not necessary, because, since a Lechi (a post of any width) is sufficient to turn a Mavoy into a Reshus ha'Yachid (mid'Oraisa), it will also render the Sukah Kasher.

(d)We refute this Kashya, on the grounds that it would not be necessary to tell us that - because having already informed us that we apply 'Migo' from Sukah to Shabbos (which is more stringent), then it is obvious that we will also apply 'Migo' from Shabbos to Sukah (which is more lenient to begin with).

6)

(a)Rava permits a Sukah whose walls consist a. of a Mavoy and the Lechi at the entrance, and b. of Pasei Bira'os (four Deyumdin, each of an Amah by an Amah). He finds it necessary to permit a Sukah whose walls consist of ...

1. ... Pasei Bira'os - which we could not have learnt from a Mavoy and the Lechi at the entrance, since they have two proper walls, whereas Pasei Bira'os have none.

2. ... a Mavoy and the Lechi at the entrance - which we could not have learnt from Pasei Bira'os - which at least has four walls (even if they are incomplete), whereas a Mavoy and the Lechi at the entrance only has three.

(b)He also needs to permit a Sukah of two walls and a Tefach even on Shabbos because of Migo, which we would not know from the reverse case (i.e. of walls that are valid on Sukos because they are valid on Shabbos [as we learned earlier]) - because although we say 'Migo' from Shabbos to Sukah (from the more strict to the more lenient) it does not follow that we also say it from Sukah (which is more lenient) to Shabbos (which is more strict).

7)

(a)According to the Tana Kama of the Beraisa, it is only the sunlight that shines through the Sechach that can invalidate the Sukah, but not the sunlight that shines through the walls - whereas according to Rebbi Yoshi'ah, the latter will invalidate the Sukah, too, if combined with the sunlight that shines in from the Sechach, it lets in more than the combined shade.

(b)He learns this from the word "v'Sakosa" (from the Lashon Sechach [in the Pasuk "v'Sakosa al ha'Aron es ha'Paroches", even though it is dealing with the Paroches, which is a Mechitzah [a wall]), to teach us - that the principles of Sechach apply to the walls, too.

(c)The Rabanan, who do not consider a wall as Sechach, learn from this Pasuk - that the top of the Paroches should be folded over slightly to form a short horizontal roof, so that it resembles Sechach.

(d)We have already learned that Rebbi requires a Sukah to be at least four by four Amos, and that Rebbi Yehudah validates a Sukah that is higher than twenty Amos. They (as well as Rebbi Shimon, who requires at least three full walls, and a third wall of one Tefach), agree with Rebbi Yoshi'ah - that a Sukah must be a permanent dwelling (though each one applies the concept differently).

8)

(a)Raban Gamliel, Beis Shamai, Rebbi Eliezer and Acherim too, all subscribe to the same opinion. Beis Shamai invalidate a Sukah, if one's table is in the house. According to Raban Gamliel - a Sukah on top of a wagon or a ship is Pasul (the former, because the height at which it is built renders it incapable of withstanding a strong wind, the latter because it sways to and fro, conveying the impression that it is only temporary.

(b)Rebbi Eliezer rules in a Beraisa - that a Sukah in the shape of a wigwam is Pasul.

(c)He also invalidates a Sukah - that consists of canes leaning against a wall. Both of these are Pasul because the roof is indistinguishable from the walls.

(d)The Chachamim validate it.

9)

(a)Acherim invalidate a round Sukah - because it does not have corners.

(b)Rebbi Yochanan does not rule like Acherim. According to him, a round Sukah is Kasher, provided twenty-four people can sit round it - because he requires minimum dimensions of four by four Amos, like the opinion of Rebbi.