Horse breed been produced. Such restrictions have led to legal challenges in the United States, sometime based on state law and sometimes based on antitrust laws. Horses can crossbreed with other equine species to produce hybrids. These hybrid types are not breeds, but they resemble breeds in that crosses between certain horse breeds and other equine species produce characteristic offspring. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, the hinny, is a cross between a stallion and a jenny (female donkey). Most other hybrids involve the zebra (see Zebroid). With
When a white horse is not a horse ambiguity of whether "is" means: In other words, the expression "a white horse is not a horse" is ambiguous between "a white horse is not identical with a horse" (true, because "white horse" is more specific than "horse"), and "a white horse is not a member of the set of horses" (obviously false). The Advocate in the dialogue is asserting that "a white horse is not [identical with] a horse," while the Objector is interpreting the Advocate's statement as "a white horse is not [a member of the group of] horses." An illustration of the alternative uses of "fei" may