9. Manipulation of expressions
9.1. Find indices
9.2. Replace indices
9.3. Scalar and scalar functions
9.4. Inert heads
9.5. Monomials
9.6. Symmetrization of an expression
9.7. Symmetric Trace-Free part
9.8. Mapping at specified positions
9.9. Coefficients
9.10. Tensor equations
