A state machine, also known as a finite-state machine (FSM), is a mathematical model used to describe the behavior of a system. It is a tool used to represent and analyze the behavior of a system by defining a set of states and the transitions between them based on a set of input events.
The state machine model consists of a set of states, which represent the possible conditions or states that the system can be in, and a set of transitions, which represent the conditions under which the system can move from one state to another. The state machine can be represented graphically as a state diagram, where each state is represented as a node and each transition is represented as an edge between the nodes.
State machines can be classified as deterministic or non-deterministic, depending on whether the next state of the system is uniquely determined by the current state and input, or whether there are multiple possible next states for a given input. In deterministic state machines, the behavior of the system is completely determined by its current state and the input, whereas in non-deterministic state machines, there may be multiple possible next states for a given input.
One of the advantages of using a state machine to model a system is that it can help to identify and eliminate potential sources of errors or bugs in the system. By defining the states and transitions of the system in a systematic way, it is possible to identify conditions where the system may enter an unexpected or invalid state, and to take appropriate action to prevent this from happening.
Another advantage of using a state machine is that it can help to make the behavior of the system more explicit and easier to understand. By representing the behavior of the system graphically as a state diagram, it is possible to visualize the behavior of the system and to identify patterns and regularities in the behavior that may not be apparent from the source code or other documentation.