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Definition and model boundary

FPRD-D30

Pre-query causal-track presentation

Exact statement

A pre-query causal-track presentation fixes a one-dimensional address line and finitely many persistent tracks before a future selector is known. At each input step a track holds or moves one address toward smaller coordinates; a demand is served only when a track occupies the demanded address at the required time.

StatusSelf-contained model; classical multi-head context identified
External reviewNo documented external or specialist review of this FPRD result is recorded.

Context

The model is a mirrored one-way multi-head automaton with a pinned address convention and a deliberately late selector. The resource is query-oblivious track placement, not unrestricted random-access memory.

Definitions

  • Tracks are placed before the selector is revealed and may hold or recede by one address per input step.
  • A complete snapshot includes the finite control state and every labelled track position before sensing at the selected cut.

Proof or evidence

The public page states the update, observation, and timing conventions and gives examples separating pre-query placement from pathwise offline width.

Model and conventions →

Verification notes

The model was reconstructed from the causal-width and cone-factorization proofs and reconciled with classical multi-head automata terminology.

Limitations

  • Tracks cannot teleport or be placed at selector-chosen addresses.
  • The model does not represent a random-access machine or a general online streaming algorithm.

Open work

Compare the pinned-coordinate convention with additional multi-head and streaming models before extending any lower bound beyond this exact presentation.

Notes

This is the mirrored head-motion geometry of classical one-way multi-head finite automata and of trailing heads. It is not claimed as a new machine model. Variants with track birth require their own placement rule; only random-access placement at the selected address trivially collapses the late-selector lower bound.