To be used in future
 Section A.6: Relativity-tensor notation Up Appendix A: Useful Mathematics Section A.8: Anticommutators 

A.7 Commutators

Commutators between objects (be they matrices or operators) are defined as We find the following useful relations (commonly used in commutator algebra) and
as well as
 Section A.6: Relativity-tensor notation Up Appendix A: Useful Mathematics Section A.8: Anticommutators