Formal Methods Concepts
• data invariant—a condition that is true
throughout the execution of the system that
contains a collection of data
•  state—the stored data which a system
accesses and alters
• operation—an action that takes place in a
system and reads or writes data to a state
• precondition defines the circumstances in which a
particular operation is valid
• postcondition  defines what happens when an operation
has completed its action