stateconditions

Stateconditions is a term used in systems modeling to denote the set of predicates and constraints that define when a system is in a given state, or when a transition to another state may occur. The term is not widely standardized and may be written as “state conditions” or “state predicates” in different sources, but it is commonly used descriptively to emphasize state-specific requirements.

In practice, state conditions appear as guard conditions on transitions in state machines, as invariants that must hold while the system resides in a state, or as preconditions for actions that change state. They help formalize the dependencies between the system’s state variables and its allowed behavior, supporting correctness reasoning and verification.

Examples include a door controller with states Closed and Open, where the transition from Closed to Open requires isUnlocked and not jammed, or a vending machine in the WaitingForCredit state that only transitions to HasCredit when a coin is accepted and the selected item is in stock. In software design, state conditions are often expressed as boolean expressions over state variables, and may be implemented as assertions, guards, or contracts.

Because the term is not part of a single standard notation, practitioners often refer to related concepts by more common terms such as guard conditions, invariants, state predicates, or preconditions. Understanding state conditions aids in designing predictable, verifiable stateful systems. See also: state machine, guard condition, invariant, precondition, contract, predicate logic.