Reference 1
Semantic Styles (chapter 3.4 in 1) There are three basic approaches to formalizing semantics: Operational semantics. Specifies the behavior of a programming language by defining a simple abstract machine on it. For simple languages, a state of the machine is just a term, and the machine’s behavior is defined by a transition function that, for each state, either gives the next state by performing a step of simplification on the term or declares that the machine has halted.
If you could revise
the fundmental principles of
computer system design
to improve security...
... what would you change?