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RECIPROCAL - Definition (451 words) |
 | {Reciprocal proportion} (Math.), a proportion such that, of four terms taken in order, the first has to the second the same ratio which the fourth has to the third, or the first has to the second the same ratio which the reciprocal of the third has to the reciprocal of the fourth. |
 | {Reciprocal ratio} (Math.), the ratio between the reciprocals of two quantities; as, the reciprocal ratio of 4 to 9 is that of 3/4 to 1/9. |
 | The reciprocal of a fraction is the fraction inverted, or the denominator divided by the numerator. |
| Reciprocal altruism - Wikipedia, the free encyclopedia (785 words) |
 | Reciprocal altruism is a form of altruism in which one organism provides a benefit to another in the expectation of future reciprocation. |
 | An example of reciprocal altruism is blood-sharing in the vampire bat, in which bats feed regurgitated blood to those who have not collected much blood themselves knowing that they themselves may someday benefit from this same donation; cheaters are remembered by the colony and ousted from this collaboration. |
 | If cheating is detected then reciprocity will end, at considerable cost to the cheater, therefore "the cheater should be selected to make up for his misdeed and to show convincing evidence that he does not plan to continue his cheating sometime in the future". |