sentences:  In particular,
  for matrices "A", "B", and "C" of dimensions "k"×"l", "l"×"m", and "m"×"n".For example, if formula_10 (the adjoint endomorphism of the Lie algebra of all "n"×"n" matrices with complex entries), then formula_11, where formula_12 is the "n"×"n" identity matrix.There are two other useful formulations