What is differential execution and what is it good for?
Differential execution is a way of executing a procedure repeatedly in which it does simultaneous serialization and deserialization. This enables it to know at every step how it's current execution differs from the prior execution. This enables it to automatically detect and respond to changes, for example changes in program state variables.
One use for this is to dynamically maintain complex interactive UI dialogs, in which it results in a source code savings of roughly an order of magnitude, and functions with provable correctness.
Here's a sourceforge project, Dynamic Dialogs with a complete implementation in Visual C++ with MFC.