Finite-State Map Selector¶
Selector model — instantiates Context-Keyed Representation Switching
Models contexts as the states of a machine and switching as guarded transitions, so the active representation can only change along legal, explicitly-allowed paths — never an arbitrary jump.
Not every switch between contexts is legal, and not every one is safe. Finite-State Map Selector models the set of contexts as the states of a finite-state machine and every switch as a guarded transition, so the active representation can only change along paths that have been explicitly allowed. Its defining property is that selection carries memory and legality: the current state constrains which state you can move to next, and each move must pass a guard condition, which makes an illegal or unsafe context jump structurally impossible rather than merely discouraged. It resolves ambiguous or conflicting cues down to exactly one current state; the raw key→map lookup it hands off to a table, and the timing of switches it hands off to a debounce.
Example¶
A robotic welding cell operates in a handful of modes, each with its own representation of what the arm may do: transit, positioned, weld, and fault. The selector permits only defined transitions — the arm cannot enter weld except from positioned, so a weld command received while in transit is rejected or forced first through positioned; from any state it can drop to fault. When two sensors disagree about whether the workpiece is seated, the disambiguation rule resolves the conflict to a single current state (say, staying in transit until a quorum agrees), rather than flickering. The result is that unsafe context jumps — a weld attempted mid-transit — simply cannot occur, because there is no legal edge for them.
How it works¶
Its distinguishing feature is that selection is stateful and legality-constrained. Because the machine knows which state it is in, the set of reachable next states is limited to explicitly-defined, guarded edges — so the model encodes not just which map but which switches are permitted from here. It first resolves incoming cues to a single unambiguous state (disambiguation), then fires only allowed transitions. It deliberately does not perform the key→map lookup for a state (a routing table does that over the resolved state) nor decide how long to dwell before switching (a hysteresis filter does that).
Tuning parameters¶
- Transition topology — which switches are legal edges. A permissive graph is flexible but admits unsafe or nonsensical jumps; a strict one is safe but can trap the system with no legal way forward.
- Guard conditions — the preconditions each transition must satisfy before it fires. Tighter guards are safer but can block a transition that reality genuinely needs.
- Disambiguation policy — how conflicting cues resolve to one state: priority order, most-recent-wins, or quorum. This sets how the machine behaves at the messy edges between contexts.
- Trap / error state — whether unrecognized or contradictory input routes to an explicit fault state (with a defined way out) or is dropped.
When it helps, and when it misleads¶
It is the right model when some context transitions are illegal or unsafe and order matters — when "you may only enter this map from that one" is a real constraint you want enforced structurally rather than by convention.
Its characteristic failures are at the extremes of its own rigidity: an over-strict topology can trap the system when a legal real-world transition was never drawn as an edge, and state explosion makes a machine with too many states unmaintainable and its guards unauditable. The classic misuse is forcing a genuinely continuous or soft context into discrete states — modeling a dimmer as an on/off switch — or piling on states until no one understands the graph. The discipline is to keep the state set minimal and reviewed, and to always include a fault state plus a human path out, so a wrong or missing edge is recoverable rather than a dead end.[n1]
How it implements the components¶
switch_transition_guard— the guarded edges are the transition guard: a switch fires only if the current state permits it and its precondition holds.context_disambiguation_rule— it resolves conflicting or ambiguous cues down to exactly one current state before any transition is considered.
It does NOT map a resolved state to its representation — that lookup is Context-to-Map Routing Table's — and it does not decide how long to wait before switching, which is Hysteresis and Debounce Filter's job.
Related¶
- Instantiates: Context-Keyed Representation Switching — it is the legality layer that keeps switching to sanctioned, ordered paths.
- Consumes: resolved cues; it hands the current state to Context-to-Map Routing Table for the actual map and the switch timing to Hysteresis and Debounce Filter.
- Sibling mechanisms: Context-to-Map Routing Table · Hysteresis and Debounce Filter · Safe Default-Map Fallback · Active-Map Status Indicator · Canary Context Switch
Editorial Notes¶
Form Classification¶
Form family: Control, Automation & Runtime
Rationale: Finite-State Map Selector operates as a live operational control that automatically routes, enforces, adapts, or responds during execution because it models contexts as the states of a machine and switching as guarded transitions, so the active representation can only change along legal, explicitly-allowed paths — never an arbitrary jump.
Independent corroboration: The frozen evidence defines Finite-State Map Selector as 'Models contexts as the states of a machine and switching as guarded transitions, so the active representation can only change along legal, explicitly-allowed paths — never an arbitrary jump', so its operative form is Control, Automation & Runtime.
Review outcome: Independent reviewer agreement; high confidence.
Origin Attribution¶
Primary origin: Computer Science & Software Engineering
Origin pattern: Single lineage
Present-day reach: Multi-domain
Rationale: Finite-state machines with guarded transitions are foundational computer-science and automata-theory mechanisms.
Related originating lineages:
- Engineering & Design — Control and embedded-systems engineering materially developed state-machine selectors for operational modes.
- Robotics & Automation — Operational modes and safety-guarded transitions materially shaped physical controller use.
Review resolution: Both reviewers agree that computer_science is primary. I retain engineering_design, robotics_automation only as formative origin lineage(s), without treating every later application as an origin. single_lineage is appropriate because the evidence supports one principal professional lineage. Reach is multi_domain as a separate applicability judgment: it does not widen or narrow the recorded provenance. Encyclopedia synthesis is true because the exact generalized artifact is an encyclopedia-authored combination or refinement. The secondary differences are reconciled with no unresolved primary-provenance ambiguity.
Encyclopedia synthesis: The exact catalogued form synthesizes established practice rather than reproducing a single standard historical label.
Review outcome: Reconciled after independent review; high confidence.
Notes¶
It governs which switches are allowed, not which map a state resolves to nor how long to wait before switching. It is the legality layer — meaningful only when paired with a lookup that turns its state into a representation and, usually, a debounce that keeps it from transitioning on noise.
[n1] A guard condition in a finite-state machine (as in UML statecharts) is a predicate that must hold for a transition to fire; an unlisted transition is simply illegal. Modeling contexts this way makes unsafe jumps impossible by construction, at the cost of rigidity — which is why a reachable fault state and an override path are part of doing it well. ↩