אמר אחד הרי עלי בעשרים ואחד הבעלים נותנים עשרים ושש

Rashi and most of the Rishonim understand this to mean that once the בעלים express an interest in being פודה we force them to pay extra קרן if someone else bids more even if they don't want to. It comes out that even thought the בעלים only may have wanted to pay 25 we force them to pay up to 30.

The Rambam has a completely different פשט in this Mishna in ערכין. The Rambam (ערכין ח:ה) writes that if the בעלים say 20 and someone else says 21 and the בעלים say nothing (they make no counteroffer), the בעלים get it for 25 (קרן + חומש). The mishna in ערכין is talking about where the בעלים make a counter offer of 21 and a פרוטה. Then they have to pay 26 + a פרוטה. As the Raavad there points out this is very difficult in the לשון of the Mishna and the sugya there. According to the Rambam why would the בעלים make a counteroffer when they can just stand by their original offer and get it for 25?

חומש on פחות משוה פרוטה

Rashi and many of the Rishonim (see for example תוס' ד"ה אין) understand that everyone agrees that there is a חיוב חומש on a פחות משוה פרוטה the question is can you be פודה the מעשר שני if the חומש is less then a שוה פרוטה

אחרונים ask according to the מ"ד who holds that חומש is not מעכב why wouldn't you be able to be פודה if the חומש is less then a פרוטה after all the פדיון is חל even if he doesn't give the חומש at all? In other words, we should say that ר' אסי and ר"ל hold that חומש is מעכב. One answer may be this is like כל הראוי לבילה אין בילה מעכבתו. The חומש is not מעכב if you can give it. However, if it is less then a שוה פרוטה and therefore you can't give it then everyone would agree that it is מעכב.

The Rambam has a different understanding of this Gemara. The Rambam (מעשר שני ה:ד) understands that the מחלוקת is whether there is a חיוב חומש of less then a שוה פרוטה and ר' אסי and ר"ל hold that if the מעשר שני is worth less then 4 פרוטות you don't need to add a חומש. In fact, the מפרשים point out that the Rambam is a בפירוש ירושלמי however the לשוןof the ברייתא is difficult for the Rambam. The ברייתא explicitly mentions that הוא וחומשו even though according to the Rambam he doesn't need to pay the חומש.

What is the דין where based on מקח it is more then 1/6 but based on מעות it is less then 1/6 or vice versa?

Shmuel holds that you can figure 1/6 based on מעות as well, and therefore if the price is 5 and you pay 6 that is אונאה of 1/6.

The Rishonim discuss the following case. The price is 51 and he paid 60. Based on the מקח he has overpaid by 9/51 which is greater then 1/6, however based on the מעות he only overpaid 9/60 which is less then 1/6. The same applies vice versa. If the price is 60 and he pays 51 based on the מקח he underpaid 9/60, less then 1/6, however based on the מעות he underpaid 9/51, which is greater then 1/6. What is the din in these cases? The Rambam paskens that you always go with the מקח and therefore where the price is 60 and he paid 51 the מקח is קיים. The מגיד משנה there asks on the Rambam how could he say that? We pasken like Shmuel that there is אונאה based on מעות also and therefore since based on מעות he underpaid more then 1/6 the מקח should be חוזר. The Ritva brings the שר מקוצי who agrees with the מגיד משנה while the Ritva himself agrees with the Rambam. Tosafos ד"ה שתות also seems to agree with the Rambam.

The ערוך השולחן explains the Rambam (and really the Ritva seems to say this) as follows. If based on the מעות it is 1/6 (e.g the price was 5 and you paid 6) then we can say that this is 1/6 and the מקח is קיים and the one who was cheated gets his money back. Why? Because no one loses. However, in a case where based on the מעות it is more then 1/6 and based on the מקח it is less then 1/6 (or vice versa) we have a contradiction. Based on one the מקח should be cancelled and based on the other the מקח should be קיים. Since we have a contradiction we need to pick 1 צד and since the עיקר according to everyone is price, we go with the price.

It comes out that we have the following anomaly. If the price is 50 and I paid 60 then the מקח is קיים and I just get the extra 10 that I paid back because it is 1/6 based on the מעות. However, if the price is 51 and I paid 60 overpaying by less (only 9) the מקח is completely בטל because based on the מקח I overpaid more then 1/6.

To summarize, the Rambam וסייעתו hold that where it is not exactly 1/6 then you always go with the מקח and Shmuel only said his דין of מעות where it is exactly 1/6. According to the מגיד משנה and others we go with both unless it is exactly 1/6 based on either the מקח or the מעות then the מקח is קיים and the extra money is returned. However, if it is more then 1/6 either based on מקח or based on מעות the מקח is חוזר. Only if based on both מקח and מעות, it is less then 1/6 do we say the מקח is קיים.

46a Rav Ashi's answer

As we saw today, Rav Ashi differs with Ula's answer in that the coin provided by the shulchani is a real matbeia, yet there is no problem of chalipin with tiv'a due to the fact that he has money at home (based on tosfos understanding of the sugya). Acc to Rav Ashi, though, why does the money returned by the purchaser (the guy paying his workers) have to be non minted coins (it seems acc to Rashi that this is not the case)? As we said in shiur, since you are "purchasing" maos for the dinar, why cant we understand that he is paying back with real money as well?

Based on maharsha in an earlier tosfos, perhaps the answer is that this allows us to learn the sugya even acc to man d'amar that אין מטבע נקנה בחליפין
Perhaps, Tosfos is telling us that money for money, even if the money is different amounts would still involve se'a be'sa and would not be considered a sale of money? The language used in tosfos , though, calls this a matbea and not an unminted coin, which seems to not be what Rav Ashi answers.

אמר שמואל לא נטל נטל ממש (Bava Metzia 44a)

Rashi understands that the Gemara's answer is that he is a שואל on the whole barrel and therefore חייב. Most of the other Rishonim (on the Gemara מ"א.) learn a different p'shat that since he wants the רביעית to stay in the barrel because it stays best there, we look at it as if he took the רביעית of wine out and put it back and therefore he was מחסר. In other words it is שליחות יד with a חסרון.

The ראב"ד has a tremendous chiddush here (הל' גזילה ג:י"ב) that if you are שולח יד on only part of the object you are only חייב on that part, (the ריטב"א is מדייק from Rashi here that he holds this way as well). The only time you are חייב for שליחות יד on the whole object is if your כוונא is to steal the whole object. The obvious question is that this is against the Gemara on מ"א: both by הניח מקלו ותרמילו where you are clearly only שולח יד on part of the animal (your כוונא is definitely not to steal the whole animal but to use it and be מחסר a little) and by ר' יעקב בר אבא. You see that if you have כוונא to steal the whole object then you are חייב even without a חסרון according to everyone, yet according to the Raavad this is exactly the case where there is a מח' whether שליחות יד צריכה חסרון or שליחות יד אינה צריכה חסרון. Additionally, if the only time you are חייב for שליחות יד on the whole object is if your כוונא is to steal the whole object, what exactly is the חידוש of שליחות יד? You are a גזלן anyway? This would seem to be why all the other Rishonim argue on the Raavad.

בעי ר' אשי הגביה ארנקי (Bava Metzia 44a)

The Gemara says that Shmuel could even be according to those who hold that שליחות יד צריכה חסרון and this case is different because he wants the רביעית of wine in the barrel so that it stays better. R' Ashi then asks what about ארנקי? The simple understanding of the Gemara is that R' Ashi's whole question is only if שליחות יד צריכה חסרון but if שליחות יד אינה צריכה חסרון then the case of ארנקי is a classic case of שליחות יד (since at the time he is מגביה he has כוונה to be מחסר by taking out a דינר) and he is for sure חייב. In fact, this is the way the Rif, Rosh and Tur pasken. However, the Rambam (הל' גזילה ג:י"ב) even though he paskens that שליחות יד אינה צריכה חסרון brings down the case of R' Ashi as a ספק how to pasken. We see from the Rambam that he held that R' Ashi's question was even if you hold שליחות יד אינה צריכה חסרון. The Acharonim work hard to understand how the Rambam could say this.

(ר' עקיבא אומר כשעת התביעה (בבא מציעא מ"ג

What case is ר' עקיבא talking about? Is ר' עקיבא talking about the same case as ב"ה and ב"ש, namely שבח?

Tosafos says it can't be. Tosafos asks, if ר' עקיבא holds that שינוי קונה then he was קונה the שבח and he should keep it, if he holds that שינוי אינו קונה then he should pay for what grows even after the תביעה. Therefore Tosafos says that ר' עקיבא is talking about where the price of the object goes up. ר' עקיבא holds that even though כל הגזלנים משלמים כשעת הגזילה a שולח יד is different and pays the value of the object כשעת התביעה even if it goes down which is a tremendous chiddush.

The בעל המאור learns that ר' עקיבא is also going on the same case as ב"ה and ב"ש (namely שבח). He explains that ר' עקיבא holds that he doesn't get the קניני גזילה to be קונה the שבח until the time of the תביעה and therefore that is the time that is קובע. In other words, any שבח until the time of the תביעה belongs to the נגזל. This answers Tosafos's objection, ר' עקיבא holds שינוי קונה but only from the time of תביעה because that is when he gets the קניני גזילה.

The Rif says the opposite of the בעל המאור. The Rif says that any שבח that the גזלן takes from the animal is his until the תביעה, after the תביעה the שבח belongs to the נגזל.