TODO: This section needs to be revised since the introduction of strict and relaxed template parameters! (Should basically forbid relaxed template parameters in typedef templates.) Old text follows:
We extend the notion of type-equivalence to include typedefs as follows:
Two instances of typedefs are type-equivalent if and only if they refer to the same canonical definition, and their canonical parameters are equal.
Some implementation hints. Given two typedef instances or references. Find greatest common ancestor. Common ancestor may simplify equivalence deduction.