In differential geometry and theoretical physics, the Petrov classification describes the possible algebraic symmetries of the Weyl tensor at each event in a Lorentzian manifold.
It is most often applied in studying exact solutions of Einstein's field equations, but strictly speaking the classification is a theorem in pure mathematics applying to any Lorentzian manifold, independent of any physical interpretation. The classification was found in 1954 by A. Z. Petrov.
Read more about Petrov Classification: The Classification Theorem, Newman–Penrose Formalism, Bel Criteria, Physical Interpretation, Examples, Generalization To Higher Dimensions, See Also