exists_sequential_schedule
plain-language theorem explainer
Any finite set of events equipped with a decidable well-founded precedence relation admits a linear ordering that posts exactly one event per tick while respecting all precedence constraints. Researchers formalizing atomicity in Recognition Science cite this when serializing finite histories without extra axioms. The proof is a direct wrapper that invokes the topoSort recursion and delegates the distinctness, coverage, and order-preservation properties to the supporting lemmas topoSort_perm and topoSort_respects.
Claim. Let $E$ be a type and let $prec$ be a decidable well-founded precedence relation on $E$ (i.e., $prec(e_1,e_2)$ asserts that $e_1$ must precede $e_2$). For any finite subset $H$ of $E$ there exists a list $σ$ of distinct elements from $H$ whose underlying set equals $H$ such that $e_1 ∈ H$, $e_2 ∈ H$ and $prec(e_1,e_2)$ together imply that the index of $e_1$ in $σ$ is strictly smaller than the index of $e_2$.
background
Precedence is the abstract relation on events defined by the abbrev Precedence (E : Type _) := E → E → Prop; the notation prec e₁ e₂ is read “e₁ must occur before e₂”. Schedule is the structure whose order field is a list of distinct events representing a one-per-tick serialization of a finite history H. The module works entirely inside the finite-history fragment of Recognition Science, deliberately independent of cost functionals or convexity, and assumes only finiteness together with decidable precedence. It supplies the constructive half of the atomicity requirement that tightens T2 in the forcing chain.
proof idea
The tactic proof opens with classical, then refines the existential witness to the pair consisting of the topoSort recursion applied to prec, wf and H together with three subgoals. The first two subgoals are discharged by the two projections of topoSort_perm; the third subgoal is discharged by a direct application of topoSort_respects to the membership and precedence hypotheses.
why it matters
The theorem supplies the existence direction used verbatim by the downstream atomic_tick theorem in the same module. It therefore completes the constructive serialization step required to tighten T2 for finite recognition histories. The result stays axiom-free and independent of the J-cost, phi-ladder and eight-tick octave structures that appear later in the framework; it therefore serves as a stable interface for any later conservation or mass-formula arguments that need a well-ordered posting sequence.
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papers checked against this theorem (showing 4 of 4)
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Alignment widens logit gap on 98% of toxic prompts
"We adapt the classical unit-cost set-cover heuristic to the token-selection setting … sort C by descending F and append tokens until their running total overtakes the gap."
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Open-source code models top Codex and GPT-3.5
"Algorithm 1 Topological Sort for Dependency Analysis"
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Greatest-solution method extends to symmetrized and supertropical semirings
"The usual approach is to first find the greatest solution... and then to solve a much harder problem of finding all minimal solutions... equivalent to the hypergraph transversal enumeration problem."
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Event languages mapped to one Temporal Datalog engine for streams
"Atomic tick (finite history): any finite recognition history admits a serialization with exactly one posting per tick that respects precedence (RS Foundation/Atomicity.lean, theorem atomic_tick)."