Gemara

(Rava): If one swore not to eat a loaf, and ate from it; he can ask to permit it (and it will be as if he did not transgress) only if he left over a k'Zayis.

Question (Rav Acha brei d'Rava): If he swore 'I will not eat', once he ate a k'Zayis, he already transgressed. If he swore 'I will not eat it, even if less than a k'Zayis remains, he should be able to permit it!

Answer #1: He swore 'I will not eat.' Permitting the oath on the rest also retroactively uproots the entire oath, so he never transgressed.

Answer #2: He swore 'I will not eat it.' If less than a k'Zayis remains, this is not important enough to permit the oath.

38a (Beraisa - R. Meir): One who takes a Klal (all-inclusive) oath is liable once. If he takes individual oaths, he is liable for each one.

R. Yehudah says, if he said 'I swear that you do not have a deposit by me, and not you, and not you... ', he is liable for each one.

(R. Yochanan): All agree that when he says 'and not you', these are individual oaths. They argue in a case that he says 'not you' to each. R. Meir calls this individual oaths, and R. Yehudah calls it a Klal.

Nedarim 66a (Mishnah - R. Akiva): If one said 'may not benefit from me - not this one, nor this...', and the first one was permitted, all are permitted. If the last one was permitted, the others are forbidden.

If one said 'benefit that I give to this person should be like a Korban, (benefit) to this one, like a Korban...', to annul them, a separate Pesach (reason to consider the vow a mistake) is needed for each one.

(Rava): The Reisha is like R. Shimon, who considers an oath forbidding several people to be a Klal, unless he says 'Shevu'ah' for each one.

26b: The case is, he made each dependent on the previous - 'they are forbidden to Shimon. Levi is (forbidden) like Shimon; Yehudah is like Levi...'

Support (Beraisa): If the middle one was permitted, the later ones are also permitted, but the earlier ones are forbidden.

Kidushin 46a (Mishnah): If one told a woman 'be Mekudeshes to me with this date, be Mekudeshes to me with this (another) date...', she is Mekudeshes only if one of them is worth a Perutah.

(Rabah): The Mishnah is like R. Shimon, who says that 'Shevu'ah, I do not owe to you, and not to you and not to you' is considered like one oath, unless he said 'Shevu'ah' to each person.

Rishonim

Rambam (Hilchos Nedarim 4:11): If one swore or vowed 'I will not give benefit to all of you', and permitted his vow or oath regarding one of them, all are permitted, for a vow that was partially permitted is totally permitted. If one said 'I will not gave benefit to Reuven and to Shimon and to Levi', and permitted this regarding Reuven, all of them are permitted. If he permitted it regarding Levi, the others are forbidden. If he said 'I will not benefit Reuven, Shimon and Levi', a separate Pesach is needed for each.

Rambam (Hilchos Shevuos 7:10): If five people were claiming a deposit from Ploni, and he said 'Shevu'ah, I do not owe you and not you and not you...', (if he owed them) he is liable for each.

Rambam (Hilchos Ishus 5:26): If one told a woman 'be Mekudeshes to me with this date, be Mekudeshes to me with this (another) date...', she is Mekudeshes only if one of them is worth a Perutah.

Rambam (27): If one told a woman 'be Mekudeshes to me with this and this and this', she is Mekudeshes only if in all they are worth a Perutah.

Rosh (Nedarim 8:5): The Ramban says that even though we normally rule like R. Yehudah against R. Shimon, here the Halachah follows R. Shimon, because our Stam Mishnah is like R. Shimon.

Question: We do not know which Masechta was taught last. (Both opinions are brought in a Mishnah in Shevuos 38a. If Shevuos followed Nedarim, we do not rely on the Stam Mishnah!)

Answer (Rosh): Another Stam Mishnah (Kidushin 46a) is like R. Shimon, and the Sugya there is like him and the Amora'im discuss his opinion.

Beis Yosef (YD 229 DH v'Chen): The Ran (66a DH ul'Inyan) also rules like R. Shimon, and says that R. Chananel does, also. However, the Rambam (Shevuos 7:10 and Nedarim 4:11) rules unlike R. Shimon.

Poskim

Shulchan Aruch (YD 229:1): If one said to a group of people 'Konam is what I will benefit to any of you' or 'that I will benefit to you, you, you', this is a Kelal. If one of them is permitted, all of them are permitted. If he said 'Konam is what I will give benefit to you', 'Konam is what I will give benefit to you', each is a separate vow. If one was permitted, the others are not permitted. According to the Rambam, if he said 'I will not benefit to this one and this one and this one', if the first was permitted, all are permitted. If the last was permitted, the rest are forbidden. If he said 'I will not benefit to this one, this one, this one', a separate Pesach is needed for each.

Beis Yosef (DH v'Chen): Our texts of the Tur say '... and to you, and to you...' This is wrong. Even without 'and', it is Klal. The Rambam holds that when he said 'and', the latter vows depend on the previous. When he did not say 'and', each is a separate vow.

Taz (3): The Tur wrote 'and to you...' The Beis Yosef says that this is not necessary, for the Halachah follows R. Shimon, who says that they are individual oaths only if he says 'Neder' to each! However, the Rambam rules like Chachamim, that it depends on whether he said 'and.' In Sa'if 4, it seems that we hold like the Rambam.

Gra (3): The Tur holds like Rashi, whose text of R. Yochanan says that when he says with 'and', all agree. Perush ha'Rosh (Nedarim 66a DH l'Zeh) says the same (according to Rabanan). The Beis Yosef holds like he wrote in the Kesef Mishneh, that the text says that even without 'and' it is a Klal. This is like Tosfos in Shevuos and Zevachim.

Note: Rashi and the Rosh say that it is a Klal only without 'and', unlike the Tur!

Gra (4): In Nedarim, the Rambam rules like R. Yehudah according to R. Yochanan, according to Tosfos' text. However, in Hilchos Shevuos the Rambam rules like R. Meir, that in either case (even with 'and') they are individual oaths, like Rebbi (Zevachim 30b). In Hilchos Ishus, he rules like R. Shimon! This is because the Stam Mishnah in Kidushin is like R. Shimon, and the Amora'im discuss his opinion. Even though the Reisha of the Mishnah in Nedarim is Stam like R. Shimon, the Rambam rules like R. Yehudah, based on his text (of R. Yochanan). This requires investigation. In Shevuos, he rules like R. Meir because the Stam Mishnah is like him.

Beis Lechem Yehudah (2): Shirei Keneses ha'Gedolah says that a partially permitted vow becomes totally permitted only when the actions are the same. I.e. both are positive (e.g. I will eat) or both are negative (I will not eat). They need not pertain to similar actions (eating or drinking). If he explicitly says that he wants to permit only part, the rest is still forbidden. Partial permission of a Cherem does not totally permit it. If a vow was Nidcheh (overridden), it is not totally permitted. E.g. if one vowed to fast until Rosh Hashanah, and due to illness he needed to eat some days, he must fast the rest of the days.

Pischei Teshuvah (4): Chavos Ya'ir (15) says that if one vowed to fast on Mondays and Thursdays for a year, and due to Ones or a Seudas Mitzvah or pain on one day he permitted his vow, even though it is totally permitted, he does not lose the reward retroactively. Also, in the future he may continue based on his initial acceptance. (Normally, one must accept a fast the previous day.) He holds like the opinion that a partially permitted vow becomes totally permitted only when it is permitted through a Pesach, but not if it is permitted through regret. Here, had he known, he still would have vowed, just he would have stipulated 'except for Ones or a Mitzvah or pain.' In practice, he should be stringent to accept again for the future.