What are the connotations of "v'Chi Yigof"?
Rashi: "Yigof", which means to push, but with connotations of striking, incorporates goring with the horns, pushing with its body, kicking with its feet and biting with its teeth.
Which case is the Torah referring to, where the Mazik and the Nizak each take half the live ox and half the dead one?
Rashi: It speaks when both are worth the same, e.g. an ox worth 200 Zuz gored an ox worth 200, irrespective of the value of the carcass.
What is the underlying principle on which this ruling is based?
Rashi: This ruling is based on the principle that a Shor Tam (it has not previously gored three times) pays for half the damage.
Rashi writes that the Torah discusses when the two oxen are equivalent in value. Why must we say so?
Rashi: If you will say that it applies always, sometimes the value of the Neveilah exceeds that of the Mazik, so if they divide the two animals, the owner of the Mazik will benefit; 1 and sometimes half the value of the Mazik exceeds that of the Nizak, and the Nizak will receive more than the value of the full damage. 2
Why does the Torah then not simply say that the Mazik must pay half the damage?
Rashi: The Torah needs to present the case the way it does to teach us that the owner pays exclusively from the body of the ox. 1
Rashi: So that, in the event that the Mazik dies, the victim may only claim the Neveilah, and if the Mazik is worth 100 and the Nizak 500, the owner can only claim the Mazik (in addition to the Neveilah of his ox) and loses the difference.
What does "v'Gam Es ha'Mes Yechetzun" now mean in a case where the two animals are not of equal value?
Rashi: It means that the Nizak takes the Neveilah, and the balance (between the Neveilah and half the damage caused by the Mazik) from the body of the Mazik.
Rashi writes that a Shor Tam pays for half the damage. What is the reason?
Rav Huna brei d'Rav Yehoshua (Bava Kama 15a): Stam oxen are considered guarded. Really, he should be exempt. The Torah fined him, to encourage him to guard his ox.
Rav Papa (Bava Kama 15a): Stam oxen are not considered guarded. Really, the owner should pay full damage. The Torah was lenient 1 , because he was not yet warned to guard it.
Hadar Zekenim (28, citing R. Baruch): How does this opinion explain why one pays full damage for Shen and Regel? There, the Torah was lenient to exempt in Reshus ha'Rabim; he pays only in the victim's Reshus. (Perhaps since Shen and Regel are so common, it is as if he was warned! - PF.)