Presumably they desired the exact symmetry for some decorative trophy.

If Lorentz invariance is not an exact symmetry, neutrinos can experience Lorentz-violating oscillations.

The combination of CPT is thought to constitute an exact symmetry of all types of fundamental interactions.

For heteronuclear diatomic molecules, the u/g symbol does not correspond to any exact symmetry of the electronic molecular Hamiltonian.

This problem can be due to supersymmetry being incorrect or not being exact unbroken symmetry.

This is also true for the third class, which is furthermore protected from radiative corrections as one still has an exact (quantum) symmetry.

The vector symmetry, U(1) corresponds to the baryon number of quarks and is an exact symmetry.

One example is color SU(3), an exact symmetry corresponding to the continuous interchange of the three quark colors.

It began in the 1950's, when C. N. Yang and Robert Mills used an exact symmetry to generalize electromagnetism.

Since different Higgs directions are related by an exact symmetry, they are all exactly equivalent.