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M .task/taskchampion.sqlite3 A "Zettelkasten/Permanent Notes/20251223161108-andre-platzer.md" A "Zettelkasten/Permanent Notes/20251223162450-web-of-science.md" A "Zettelkasten/Permanent Notes/20251223162954-snowballing.md" A "Zettelkasten/Permanent Notes/20251223163648-deterministic-parity-automata.md" A "Zettelkasten/Permanent Notes/20251223165340-mealy-machines.md" A "Zettelkasten/Permanent Notes/20251223170627-finite-state-machines.md" A "Zettelkasten/Permanent Notes/20251223171835-moore-machines.md"
50 lines
1.6 KiB
Markdown
50 lines
1.6 KiB
Markdown
---
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id: 20251223170627
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title: Finite State Machines
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type: permanent
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created: 2025-12-23T22:06:27Z
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modified: 2025-12-23T22:39:00Z
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tags: []
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---
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# Finite State Machines
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Finite State Machines are a computer science term for
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machines that have a finite number of states, with clearly
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defined transitions between them. Sometimes, FSM are
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referred to simply as *state machines*.
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FSM are an abstraction of a computational system. FSM are
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heavily used in systems that have clearly defined discrete
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states. Examples include traffic lights, elevators,
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combination locks, or others.
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FSM have **actions**. Actions are the unabstractified
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version of whatever the execution is. For physical systems,
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it might be something like turning a motor on.
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FSM can be categorized into two main categories:
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## Acceptors (or 'detectors' or 'recognizers') Acceptors are
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a type of FSM that produce binary output, recognizing
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whether or not a given input is accepted. Examples of
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systems that are acceptors include things like ready-commit
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systems, or a password checker. These systems have an input,
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and reach a state that determines the input is acceptable,
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or incorrect.
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## Transducers
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Transducers are a set of finite state machines that produce
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an output based on input or state using *actions*. Actions
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in this case represent a transition between state that
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also has some external change. A finite state machine of an
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elevator would have actions of the elevator changing between
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floors, for example.
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Transducers with respect to control have two different
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types:
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[[mealy-machines]] -- these have output depend on state and input
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[[moore-machines]] -- these have output depend on state ONLY
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