Alternative sign — the concept taken from the section of genetics or, generally telling, – biology, the famous Austrian scientist Gregor Johann Mendel entered it.
The main contribution to development of science of Gregor Mendel is the theory of heredity. It divided signs into prepotent and recessive (those which suppress, and those which are suppressed). And as a reference point for Mendel served alternative signs, that is those which had at peas grades (on the basis of the experiments made over crossing of peas he constructed the theories) two options that accurately differed. Alternative sign experimental peas had smooth or wrinkled seeds, a white or pink flower, high or low plants.
Thus, alternative signs are qualitative signs which cannot be present at one concrete organism at the same time, they exclude presence of each other. The alternative sign accepts only two values: 1 — existence of sign; 0 — lack of sign.
It was the conscious choice from the researcher Mendel. Being based only on alternative signs, it narrowed research problems, and it allowed to define the general laws of inheritance. More than seven years Mendel made the experiments and only in 1965 dared to submit the manuscripts under the name "Experiments over Vegetable Hybrids" to Society of scientists. In them he formulated the principles of transfer of hereditary signs from parental organisms to their descendants. These principles became basis for classical genetics. But, as well as many research works, this was doomed for many years oblivion and misunderstanding too, and only later was for many years recognized as contemporaries. Today the alternative sign can know and other application. For example, the goods can be rejected or meet standards, the individual can be either men's, or a female, the population of the state is divided into rural and city.