Abstract

An irreducible reflexively autocatalytic and food-generated set (irrRAF) is an inclusion-minimal self-sustaining reaction subsystem of a catalytic reaction system. Steel, Hordijk and Smith (J. Theor. Biol., 2013) gave a criterion for deciding whether a supplied list of kk irrRAFs is complete, that is, whether every irrRAF of the system appears on the list. Their procedure runs in polynomial time for each fixed kk, with an exponent that grows with kk, and they asked whether the problem is fixed-parameter tractable in kk. We show that it is not, unless FPT=W[P]\mathsf{FPT}=\mathsf{W[P]}: exact completeness certification is co-W[P]\mathsf{co\text{-}W[P]}-complete when parameterized by the number of listed irrRAFs, and coNP\mathsf{coNP}-complete without parameterization. Hardness already holds for systems with a single food molecule whose supplied family consists of kk pairwise reaction-disjoint simple catalytic cycles. The reduction starts from MINIMUM AXIOM SET. Each listed cycle is a guard whose unique omitted reaction selects one axiom; decoder reactions read the omission, a literal implication network derives the remaining statements, and a single closing reaction supplies the common catalyst that makes everything else self-sustaining. Every unlisted irrRAF is shown to determine a generating axiom set, including when the implication system is cyclic. Membership follows from the deletion criterion together with the bounded-nondeterminism characterization of W[P]\mathsf{W[P]}. A second, Lean-verified reduction from kk-CLIQUE shows that no algorithm runs in time f(k)No(k)f(k)\,N^{o(k)} unless the Exponential Time Hypothesis fails, so the exponent of the known algorithm cannot be made sublinear in kk; the problem is fixed-parameter tractable in kk plus the size of the largest listed irrRAF. Consequences for the problem of finding one more irrRAF and for bounded-delay enumeration are derived. The finite reductions, the validity of the supplied families, the exact parameter, the one-deletion irreducibility test and the deletion criterion are verified in the Lean 4 proof assistant with warnings promoted to errors; the complexity-class transfers are conventional proofs given in full.