Reciprokitet

Reciprokitet, or reciprocity, is a concept describing the mutual exchange of actions, goods, or signals between parties or systems. It denotes a symmetry of interaction in which one side’s behavior prompts a corresponding or return response from the other.

In social sciences, reciprocity refers to the voluntary exchange of resources, favors, or support that helps sustain social ties and cooperation. Direct reciprocity occurs when A helps B with the expectation that B will help A in return. Generalized reciprocity involves helping without a specific expectation of return to the same person, often fostering broader social cohesion. Reciprocity can be influenced by norms, reputation, and the perceived equity of exchanges.

In physics and engineering, the reciprocity principle states that in linear, passive, time-invariant systems the response at a point due to a source at another point is unchanged when the source and observation points are swapped. This Lorentz reciprocity underpins many measurement techniques in acoustics, electromagnetism, and circuit theory, and has implications for antenna design, imaging, and network analysis.

In mathematics, reciprocity describes deep connections between seemingly different objects. The quadratic reciprocity law links the solvability of certain quadratic congruences in two primes, and higher reciprocity laws (cubic, quartic, and Artin reciprocity) connect number theoretic properties to algebraic structures such as field extensions.

Reciprocitet appears across disciplines to describe mutual influence and symmetric relations, with specific formal definitions and theorems tailored to each field.