This result is not general, as more realistic population structures do not give this equivalence.
Their system proves fewer program transformations as equalities, requiring instead the more difficult notion of observational equivalence.
In contrast, in the presence of viscosity, there is no such equivalence.
Given this framework, we can say precisely what is meant by equivalence.
The attributes were allowed to vary across three chosen levels (representing an improvement to or an equivalence to the status quo) across the options.
In this section we give the precise statement of this equivalence.
The equivalence relation that only considers the public interface will be more useful to the programmer than intensional equality, because it is more permissive.
We use an equivalence on trees instead of worrying about representation.
