A type of symmetry law, an important example of which is flavor symmetry, an approximate internal symmetry law obeyed by the strong interactions of elementary particles. According to the successful theory of strong interactions, quantum chromodynamics, flavor symmetry is the consequence of the fact that the strong force (the so-called glue force, mediated by the SU^color₃ gauge field) is the same between any two quarks, the constituents of hadrons. It follows that if all the kinds (flavors) of quarks had the same mass, strong interactions would have the symmetry SU^flavor_N, where N is the number of quark flavors. As a result, if nonstrong (electromagnetic and weak) interactions were neglected, then hadrons would occur as degenerate (all having the same mass) multiplets (irreducible representations) of the group SU_N.