The subject of this book sometimes goes by the name “programming methodology”, “science of
programming”, “logic of programming”, “theory of programming”, “formal methods of
program development”, or “verification”. It concerns those aspects of programming that are
amenable to mathematical proof. A good theory helps us to write precise specifications, and to
design programs whose executions provably satisfy the specifications. We will be considering the
state of a computation, the time of a computation, the memory space required by a computation, and
the interactions with a computation. There are other important aspects of software design and
production that are not touched by this book: the management of people, the user interface,
documentation, and testing.