1) A "SHECHUNAS KEVAROS"
OPINIONS: The Mishnah in Ohalos (16:3) discusses the circumstances under which a group of corpses found buried in one place is evidence that the place is a cemetery. The Mishnah teaches that when one finds three corpses within approximately four or eight Amos of each other, the area is considered a "Shechunas Kevaros" -- a "neighborhood of graves." The Mishnah states that in such a case, one must check 20 Amos around the graves to ascertain that there are no other graves in the area.
Does the Mishnah's teaching apply only when one finds three graves in a particular order or formation, or when one finds three graves in any order?
(a) The RASHBAM (DH u'Bodek) writes that in the case of four Amos, one finds three corpses buried within four Amos, and the three corpses are lying side by side (as opposed to at an angle from each other). Based on the Mishnah earlier (see diagram in Rashbam, 101a), there clearly are many possibilities for where in the family burial cave (Me'arah) these corpses could be positioned. In the Mishnah earlier, Rebbi Shimon and the Rabanan disagree about how many graves are built in each Me'arah. They agree, however, about the general layout of a family burial plot: the plot is comprised of two Me'aros which face each other, with a Chatzer (courtyard) in the middle, between the two Me'aros. Accordingly, the three corpses which one finds may be the three corpses at the top of a Me'arah, which means that one must search the correlating sides of what potentially might be a family Me'arah, and then he skips the area of what might be the adjacent Chatzer (where no corpse would be buried), and he searches the next area, opposite the discovered graves, for another Me'arah. However, the three corpses may also face two other directions as well; they could be lying on the right or left side of a Me'arah. It must be that when the Mishnah states that one must check 20 Amos for another corpse, it means that one must check in multiple directions, following the standard design of a family burial plot.
TOSFOS (DH me'Arba) asks that this explanation seems difficult in light of the Gemara here. The Gemara asks that the Mishnah in Ohalos does not correspond to any of the opinions in the Mishnah here. According to the Rabanan, each Me'arah is four by six Amos. While the width of four Amos is understandable, it does not seem consistent with the Mishnah's comment that a person must check 20 Amos for other graves. Since the length of the Me'arah, Chatzer, and second Me'arah together is 18 Amos, why does the Mishnah require that a person check 20 Amos?
The Tana of the Mishnah there cannot be Rebbi Shimon, because he maintains that each Me'arah is eight Amos long, and thus the total length which one must check would not be 20 Amos but 22 Amos -- two Me'aros, each of which is eight Amos long, and the Chatzer, which is six Amos long.
Tosfos asks that the Gemara seems to use a roundabout way to prove that the Mishnah in Ohalos does not concur with the Mishnah here. The Gemara should say merely that since the Mishnah here states that each grave must be one Amah wide, and the space between it and the next grave must be one Amah (except for corners), there cannot be a case according to the Mishnah here where there are three corpses buried within four Amos. Tosfos answers this question by saying that the Mishnah in Ohalos still can follow Rebbi Shimon ben Gamliel, who says that one can establish graves "Lefi ha'Sela" -- "according to the strength of the rock (in the graveyard)." When the RITVA quotes the explanation of the Rashbam, he indeed inserts that the graves could be within four Amos according to the opinion of Rebbi Shimon ben Gamliel.
However, Tosfos has a number of other difficulties with the explanation of the Rashbam. He asks that the same Mishnah in Ohalos states that when one searches for graves, he must check only the second Amah after the corpse he found. This seems to be consistent with the Mishnah here, which maintains that a second corpse is never placed closer than one Amah to the first corpse (when they are placed side by side). How can this Mishnah discuss a case in which three corpses are buried side by side within four Amos of each other? The Mishnah itself (100b) states that the width of every grave is one Amah, and thus three graves with two spaces between them should comprise at least five Amos!
(b) Tosfos quotes RABEINU TAM who argues that the Gemara's case involves two graves at the top of a Me'arah and one grave at the corner closest to the top of the Me'arah. The last grave on top of the Me'arah is spaced only a half-Amah away from the first grave nearest the top of the Me'arah. For some reason, Rabeinu Tam discounts the half-Amah by half-Amah square that is between these graves. It is possible that he discounts that area because the diagonal of the square is less than one Amah; consequently, the first corpse near the top of the grave indeed is within four Amos of the other two corpses at the top of the Me'arah. (This explanation, however, does not seem consistent with the Ritva's interpretation of Rabeinu Tam's words.) According to Rabeinu Tam, there is only one possible set-up of the Me'aros and Chatzer, as the top corner of the Me'arah was found. One therefore can look exactly where he would think the other graves should be (according to the standard family burial area as described by the Mishnah here). (Y. MONTROSE)
2) A "BEIS KOR" OF "AFAR"
OPINIONS: The Mishnah teaches that when one says that he is selling a Beis Kor (thirty Se'ah) of earth ("Afar"), ditches more than ten Tefachim deep and rocks more than ten Tefachim high are not included in the sale. Ditches less than ten Tefachim deep and rocks less than ten Tefachim high are included in the sale.
Why does the Mishnah mention specifically that a Beis Kor of "Afar" is being sold? The Mishnah should say simply "Beis Kor," and it would be obvious that the Mishnah is referring to land. Even if one suggests that the term "Beis Kor" alone is not specific enough, the Mishnah should use the more common term, "Karka" ("land").
(a) The RASHBAM (DH Beis Kor Afar) explains that if the seller would not have said "Afar," he would have been able to give the buyer any type of land, even a Beis Kor of rocks. He could have claimed that he sold the land in order for the buyer to build a house on it, or for the buyer to spread out fruit on it. The AYELES HA'SHACHAR points out that the buyer also would have had this intention in mind (because, obviously, the validity of the sale depends on the buyer's intention as well). "Afar" denotes land which one can plant. Accordingly, deep ditches and large rocks are not included.
The RASHBA quotes others who question the Rashbam's logic. If the word "Afar" denotes plantable land, why are ditches not included? After all, the insides of ditches can be planted. The Rashba answers that "fit for planting" refers to the Beis Kor as a single, contiguous unit; the buyer does not want to have to plant his field in different sections (part above ground, and part inside a ditch). Similarly, the Rashba suggests that the buyer does not want to have to plant in what looks like two or three different places.
(b) TOSFOS (DH Beis Kor) explains that the Mishnah says "Afar" in order to teach that the buyer must accept rocky areas in the field when the rocks are less than ten Tefachim high.
(c) The Rashba quotes others who explain that in fact the terminology "Beis Kor Afar" is exactly how people normally talk (in the times of the Tana of the Mishnah) when they buy or sell land. (Y. MONTROSE)