Complementarity

Complementarity is a concept in a number of fields:

In economics, it is a concept similar to that of externality. See Complementarity (economics).
In physics, it is a basic principle of quantum theory. See Complementarity (physics).
In molecular biology, it is a property of nucleic acid molecules. See Complementarity (molecular biology)
In systems thinking, it is a principle concerning the observability of system behaviour. See Complementarity (systems thinking)