Sinonimi: conservation of parity | space-reflection symmetry | mirror symmetry
ETYM Latin paritas, from par, paris, equal: cf. French parité. Related to Pair, Peer an equal.
1. Parity is conserved in a universe in which the laws of physics are the same in a right-handed system of coordinates as in a left-handed system; SYN. conservation of parity, space-reflection symmetry, mirror symmetry.
2. Functional equality.
3. (Mathematics) A relation between a pair of integers: if both integers are odd or both are even they have the same parity; if one is odd and the other is even they have different parity.
4. Condition or fact of having born children.
A technique for testing transmitting data. Typically, a binary digit is added to the data to make the sum of all the digits of the binary data either always even (even parity) or always odd (odd parity).
In economics, equality of price, rate of exchange, wages, and buying power. Parity ratios may be used in the setting of wages to establish similar status to different work groups. Parity in international exchange rates means that those on a par with each other share similar buying power. In the US, agricultural output prices are regulated by a parity system.
The quality of sameness or equivalence, in the case of computers usually referring to an error-checking procedure in which the number of 1s must always be the same—either even or odd—for each group of bits transmitted without error. If parity is checked on a per-character basis, the method is called vertical redundancy checking, or VRC; if checked on a block-by-block basis, the method is called longitudinal redundancy checking, or LRC. In typical modem-to-modem communications, parity is one of the parameters that must be agreed upon by sending and receiving parties before transmission can take place. See the table. See also parity bit, parity check, parity error.
Of a number, the state of being either even or odd. In computing, the term refers to the number of 1s in the binary codes used to represent data. A binary representation has even parity if it contains an even number of 1s and odd parity if it contains an odd number of 1s.
For example, the binary code 1000001, commonly used to represent the character “A”, has even parity because it contains two 1s, and the binary code 1000011, commonly used to represent the character “C”, has odd parity because it contains three 1s. A parity bit is sometimes added to each binary representation to adjust its parity and enable a validation check to be carried out each time data are transferred from one part of the computer to another. The parity bit is added as either a 1 or a 0 so that, after it has been added, every binary representation has the same parity. So, for example, the codes 1000001 and 1000011 could have parity bits added and become 01000001 and 11000011, both with even parity. If any bit in these codes should be altered in the course of processing the parity would change and the error would be quickly detected.