The claim

Let constraint capacities cᵢ ≥ 0 evolve as ċᵢ = Pᵢ(c) − dᵢ(t)cᵢ, with dᵢ(t) ≥ d₀ > 0, Pᵢ continuous, depending only on the capacities that produce cᵢ (its parents in the production graph), and Pᵢ → 0 uniformly as those parents go to zero. There is no basal production.

Acyclic graphs go extinct. Order the capacities topologically. A capacity with no parents has ċᵢ ≤ −d₀cᵢ and decays exponentially. If all of cᵢ’s parents tend to zero, Pᵢ eventually falls below any ε, so lim sup cᵢ ≤ ε/d₀ for every ε, and cᵢ → 0. By induction every capacity tends to zero.

Ancestry. A capacity’s ancestors form a forward-closed set, so the same argument applied to them shows: if none of a capacity’s ancestors lies on a cycle, it tends to zero. A capacity that does not decay has a productive cycle among its ancestors. Removing a feedback edge set, so that the graph becomes acyclic, extinguishes every capacity, provided the knockout leaves each Pᵢ vanishing as its remaining parents do.

What it does not say

  • That a cycle suffices. The two-constraint model of CASE-189 has a cycle and goes extinct from small seeds and above a damage threshold.
  • That the cycle is closure. A self-loop, a capacity producing itself, satisfies the necessary condition. Closure in TERM-070’s sense, and in CLAIM-395’s, needs at least two mutually dependent constraints, and CASE-161 shows a self-dependent production rule does not regenerate a zeroed rule. The theorem’s necessary condition is weaker than closure.
  • Anything about systems with basal production or an outside supply. An exogenous source keeps an acyclic graph alive; that is the externally maintained case.
  • That real chemistry decays to zero. The hypothesis of no basal production and decay to zero is the limit of infinite affinity, with irreversible decay. Under local detailed balance the decay c ⇌ W has a back reaction, and with any waste present the capacities of an acyclic graph relax to (d′/d)[W], not to zero. The proof and the warrant stand for the stated hypotheses.
  • That the production cycle is a stoichiometric cycle. The graph is one of catalytic influence. Catalysts cancel out of the stoichiometric matrix, so a cycle of mutual catalytic production is not a cycle in the reaction network’s kernel; steady currents run on fuel-to-waste cycles (THEORY-1248). Mossio, Montévil and Longo’s closure likewise needs another member, and their hydrological cycle is a cycle of processes that is not closure (LIT-1888).