5.5. MakeRule

Apart from the coding aspects solved by the Index* functions, there are other, more mathematical issues which must be adressed. For instance, given a rule LHS→RHS how can we apply the rule on expressions which are equivalent to LHS but indices are permuted due to symmetries or metric shifting? Can we apply the rule on all vbundles or just on some of them? These kind of options are controlled by MakeRule, the second most complicated function in xTensor` after ToCanonical. This function uses the properties of the metric tensors, and hence we delay its description to subsection 8.1 below.

Created by Mathematica  (May 16, 2008)