1 Implementation 12 Other Work

We give a precise de nition of evolving algebras as nondeterminis tic mathematical machines All proofs in the paper are based on this de nition First we de ne constant propagation as a transformation on evolving algebras Then we extend evolving algebras by macro de nitions and de ne folding and unfolding transformations for macros Next we introduce a simple transformation to atten transition rules Finally a pass separation transformation for evolving algebras is presented For all transformations the operational equivalence of the resulting algebras with the original algebras is proven In the case of pass separation we show that the results of the computations in the original and the transformed evolving algebra are equal Next we apply pass separation to a simple interpreter Finally a comparison to other work is given