What question did this study set out to answer?

The aim is to define a robust method for initial-state selection in TUS OS that guarantees uniform randomness.

June 3, 2026Open Access

CAST v1 — Canonical Initial State Selection for TUS OS

Key Points

The aim is to define a robust method for initial-state selection in TUS OS that guarantees uniform randomness.
Establishes a uniform selection process over 64 TUS states.
Defines mathematical properties and requirements for randomness.
Details mechanisms for replay evidence and interactions with other modes.
CAST ensures uniform selection independent of the question meaning.
It preserves evidence sufficient for independent verification of the selection process.
All downstream meanings emerge only after the execution of CAST, adhering to specified invariants.

Abstract

Abstract CAST v1 defines the canonical initial-state selection contract for TUS OS. CAST fixes the initial state of a TUS run as the sole stochastic act at start-state admission. It selects uniformly over the 64 TUS states, remains independent of question meaning, and preserves replay evidence sufficient for an independent verifier to reproduce the selected start. The specification defines CAST’s mathematical properties, causality model, randomness requirements, canonical byte-rejection sampling method, receipt evidence requirements, Provided-state boundary, interaction with GUIDANCE and active LANDING modes, prohibited behaviours, and the normative invariant that all downstream meaning emerges only after CAST, from structure. This upload contains the public v1 CAST specification PDF and a supporting SHA-256 record for file-integrity verification. Files included: CAST v1 — Canonical Initial State Selection for TUS OS. pdfPrimary public v1 specification. Defines CAST as the TUS OS mechanism for canonical initial-state selection, including uniform selection over 64 states, question independence, byte-rejection sampling, replay evidence, receipt placement, Provided-state boundaries, and active-mode interaction. CASTᵥ1SHA256ₛupportingₜext. txtSupporting integrity record for the PDF. Provides the SHA-256 hash, file size, generation timestamp, and verification note. The SHA-256 hash for the PDF is: a489e867d5a277e3f49654b408481cb754393ceb7e323f552248797332c69fa5

CAST v1 — Canonical Initial State Selection for TUS OS

Key Points

Abstract

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