Gauge equivalence of injective matrix product state tensors
= Gauge equivalence of injective matrix product state tensors
The virtual <similarity transformation> $A^i\mapsto XA^iX^{-1}$ leaves every periodic MPS amplitude invariant by cyclicity of the <matrix trace>. The <fundamental theorem of matrix product states> says that, up to an overall phase, this is the only ambiguity for injective uniform tensors.