\documentclass[11pt,a4paper]{article} % --------------------------------------------------------------------------- % Effective approximation, low-intensity bounds, and finite-size effects for % autocatalytic emergence in reversible polymer networks. % % Manuscript byline intentionally blank. % Build: pdflatex main; bibtex main; pdflatex main; pdflatex main. % --------------------------------------------------------------------------- \newcommand{\PaperAuthor}{} \newcommand{\PaperAffiliation}{} \newcommand{\PaperDate}{15 October 2026} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{lmodern} \usepackage{microtype} \usepackage[a4paper,margin=1.05in]{geometry} \usepackage{amsmath,amssymb,amsthm,mathtools} \usepackage{booktabs} \usepackage{array} \usepackage{enumitem} \usepackage{xcolor} \usepackage{graphicx} \usepackage{tikz} \usetikzlibrary{arrows.meta,positioning,calc,decorations.pathreplacing} \PassOptionsToPackage{hyphens}{url} \usepackage{url} \usepackage[colorlinks=true,linkcolor=blue!55!black,citecolor=blue!55!black,urlcolor=blue!55!black]{hyperref} \setlist{itemsep=2pt,topsep=3pt} \setlength{\emergencystretch}{1.5em} \theoremstyle{plain} \newtheorem{theorem}{Theorem}[section] \newtheorem{proposition}[theorem]{Proposition} \newtheorem{lemma}[theorem]{Lemma} \newtheorem{corollary}[theorem]{Corollary} \theoremstyle{definition} \newtheorem{definition}[theorem]{Definition} \newtheorem{example}[theorem]{Example} \theoremstyle{remark} \newtheorem{remark}[theorem]{Remark} % Breakable typewriter identifiers for Lean names: \lean{Foo.bar_baz} % (raw underscores permitted; break points after '.' and '_'). Not for captions or math. \makeatletter \let\lean@us=_ \let\lean@end\relax \DeclareRobustCommand{\lean}[1]{\begingroup\ttfamily\lean@scan#1\lean@end} \def\lean@scan#1{\ifx#1\lean@end\endgroup\else\lean@char{#1}\expandafter\lean@scan\fi} \def\lean@char#1{\ifx#1\lean@us\char`\_\allowbreak\else\ifx#1.\char`\.\allowbreak\else\ifx#1/\char`\/\allowbreak\else#1\fi\fi\fi} \makeatother \newcommand{\leanrefs}[1]{\par\nopagebreak{\small\raggedright\textup{Lean: #1.}\par}} \newcommand{\conventional}{\par\nopagebreak{\small\raggedright\textup{Conventional proof; not formalised.}\par}} \newcommand{\mixed}[1]{\par\nopagebreak{\small\raggedright\textup{Conventional proof; Lean-checked components: #1.}\par}} \newcommand{\Prob}{\mathbb{P}} \newcommand{\cl}{\mathcal{C}} \newcommand{\qt}{\mathrm{qt}} \newcommand{\spc}{\mathrm{sp}} \newcommand{\eps}{\varepsilon} \newcommand{\ee}{\mathrm{e}} \newcommand{\Nat}{\mathbb{N}} \newcommand{\Real}{\mathbb{R}} \newcommand{\Rat}{\mathbb{Q}} \newcommand{\R}{\mathcal{R}} \newcommand{\word}[1]{\mathtt{#1}} \DeclareMathOperator{\RAF}{RAF} \title{Quantitative analysis of critical-window profiles\\ for autocatalytic emergence} \author{} \date{\PaperDate} \hypersetup{pdftitle={Quantitative analysis of critical-window profiles for autocatalytic emergence},pdfauthor={}} \begin{document} \maketitle \begin{abstract} The critical-window law for reflexively autocatalytic and food-generated (RAF) sets in the reversible binary-polymer model states that, when the mean number of reactions catalysed per molecule grows like $\lambda n$, the RAF probability converges to $S_\nu(1-\ee^{-\lambda})$, where $S_\nu$ is the probability that ordinary reversible closure of the food set is unbounded in an infinite field of independently open reaction channels. The law is known for the ordered split-position catalogue ($\nu=\spc$) and for the commuting-factor quotient catalogue ($\nu=\qt$). It is an existence theorem: it names the limit but says nothing effective about its value, its shape near zero, or what a finite network actually does. This paper answers those three questions. For both profiles, a construction gives a terminating algorithm which, given rational openness $a$ and rational tolerance $\eps$, returns a rational interval of width below $\eps$ containing $S_\nu(a)$, with an explicit approximation error $1/m+(2^{L+1}-2)(1-a^{L+1})^r$ for a computable seed length $L$ and record index $r$, uniform on every openness interval bounded away from zero. The key estimate is a finite-cap record contraction proved without conditioning on survival and without independence between repair attempts. Second, tracking total word length along productive closure histories replaces a coefficient of order $\binom{J}{r}$ over enormous channel caps by $C_r^\nu\le36^r2^{r(r-1)/2}$, giving $\log S_\nu(a)\le-\log^2(1/a)/(2\log2)+O(\log(1/a))$ and exact certificates such as $S_\nu(10^{-20})<10^{-629}$. Third, at fixed word length $n$ the probability that some singleton RAF exists is exactly $1-(1-p)^{248}$ (split) or $1-(1-p)^{234}$ (quotient), so the finite RAF probability is linear in $p$ at zero while the limiting profile is flatter than every power; this order-of-limits effect is quantified with rational two-sided predictions and two fully explicit examples at $n=16$. Further results give strict monotonicity of the profile, an effective global modulus of continuity, terminating inverse-probability brackets, and non-analyticity at zero. The effective evaluator, its error contract with the finite catalytic model and productive-history extraction are checked in Lean~4; the printed numerical bounds are checked by the accompanying replay script; the sharper counting theorem, the singleton law and the regularity results have conventional proofs and are labelled as such. \end{abstract} \noindent\textbf{Keywords.} autocatalytic sets; RAF theory; binary polymer model; critical window; computable analysis; certified numerics; productive histories; finite-size effects; formal verification. \medskip \noindent\textbf{MSC 2020.} 60K35, 92E20, 05C80, 03D78, 68V20. \section{Introduction}\label{sec:intro} A reflexively autocatalytic and food-generated set, or RAF, is a nonempty family of reactions each of whose reactants can be built from a food set using reactions of the family, and each of whose reactions has a catalyst among the molecules so produced. The notion was distilled by Steel~\cite{steel2000emergence} from Kauffman's collectively autocatalytic sets~\cite{kauffman1986autocatalytic,kauffman1993origins} and Eigen's hypercycles~\cite{eigen1971selforganization}, and has been developed into a structural theory with polynomial-time detection algorithms~\cite{hordijk2004detecting,hordijk2012structure,hordijk2015algorithms,steel2019autocatalytic}; see~\cite{hordijk2010autocatalytic,hordijk2017chasing} for surveys. RAF theory is deliberately structural: it asks which reaction families are self-sustaining in principle, and separates that question from kinetics, thermodynamics and molecular inventories. In particular a reaction whose product catalyses it is a singleton RAF, since the catalyst need not be present before the first hypothetical firing. This feature turns out to govern the finite-size behaviour studied below. The standard random test bed is the binary polymer model~\cite{kauffman1986autocatalytic,steel2000emergence,hordijk2004detecting}: molecules are binary words of length at most $n$, reactions are ligations and their reverse cleavages, the food set consists of the words of length at most two, and each molecule catalyses each reaction independently with a probability chosen so that a molecule catalyses $f_n$ reactions on average. Mossel and Steel~\cite{mossel2005random} showed that $f_n$ growing linearly in $n$ is the relevant scale, and simulations~\cite{hordijk2011required,hordijk2016variable,hordijk2019diversity} display a steep but smooth rise of the RAF probability within a narrow range of $f_n/n$. The consolidated critical-window analysis~\cite{combinedwindow2026} identifies the limit on this scale for both the ordered \emph{split-position} catalogue and the \emph{commuting-factor quotient} catalogue used by the public generator of Varanasi and Korenaga~\cite{varanasi2026emergence,varanasi2026repository}. In either model, if $f_n/n\to\lambda>0$ then \begin{equation}\label{eq:law} P_n^\nu(p_n)\longrightarrow\Theta_\nu(\lambda)=S_\nu(1-\ee^{-\lambda}),\qquad \nu\in\{\spc,\qt\}, \end{equation} where $S_\nu(a)$ is the probability that ordinary reversible closure of the food set is unbounded in an infinite field of reaction channels that are independently open with probability $a$. The profile $S_\nu$ is continuous and nondecreasing, $S_\nu(0)=0$, $S_\nu(1)=1$, and $00$, does an explicit algorithm terminate with a rational interval of width below $\eps$ that provably contains $S_\nu(a)$? \item \emph{Shape.} What can be proved about $S_\nu$ near zero, about strict monotonicity, inverse probabilities and regularity? \item \emph{Finite size.} What does the finite catalytic model at a given $(n,p)$ actually satisfy, and how does its behaviour near $p=0$ differ from that of the limit? \end{enumerate} An answer to one is not an answer to the others. A certified evaluator can exist while being astronomically expensive; a sharp small-openness bound can be proved without any interior evaluation; and a finite network can be governed at small $p$ by a mechanism that is invisible in the limit. \subsection*{Main results} Write $M_n=2^{n+1}-2$ for the number of molecules and $R_n^\nu$ for the number of channels of cap $n$; let $p$ be the molecule--channel catalytic probability and $a$ the static channel openness. \begin{enumerate}[label=\textbf{(\Alph*)},leftmargin=2.6em] \item \textbf{Effective approximation and a certified evaluator} (Theorems~\ref{thm:approx} and~\ref{thm:algorithm}). For a computable seed length $L=L_\nu(q,m)$ and the caps $D_r=2^r(L+2)-L$, \[ 0\le e^\nu_{D_r}(a)-S_\nu(a)\le\frac1m+(2^{L+1}-2)(1-a^{L+1})^r\qquad(a\in[q,1]), \] where $e^\nu_B(a)$ is the finite-cap probability that closure generates a word longer than $B$. Since $e^\nu_B(a)$ is a finite rational computation, this yields a terminating rational enclosure algorithm for $S_\nu$ at every rational $a\in[0,1]$, uniform on $[q,1]$. The heart of the proof is a \emph{record contraction} (Lemma~\ref{lem:contraction}): each escape beyond a cap exposes a fresh record word from which any missing short target can be repaired using at most $\ell+1$ channels of strictly larger product length, and the repair coordinates are disjoint from the exposed prefix. No conditioning on eventual survival and no independence between attempts is used. \item \textbf{Total-length history bounds} (Theorem~\ref{thm:history}, Corollary~\ref{cor:log}). Along a productive closure history every previously used channel stays settled, so the number of legal next channels is bounded by the square of the number of available types plus the number of cleavage slots, both of which are controlled by the \emph{total word length} of the current set. This gives $S_\nu(a)\le C_r^\nu a^r$ with $C_r^\nu\le36^r2^{r(r-1)/2}$ and hence \[ \log S_\nu(a)\le-\frac{\log^2(1/a)}{2\log2}+O(\log(1/a)), \] replacing the earlier coefficient $\binom{J_r}{r}$ over a channel cap of size $J_r\approx 2^{2^{r+2}}$. Bounds such as $S_\nu(10^{-4})<10^{-15}$ and $S_\nu(10^{-20})<10^{-629}$ combine kernel-checked coefficient arithmetic with the conventional polymer census of Theorem~\ref{thm:history}. \item \textbf{Exact singleton law at finite size} (Theorem~\ref{thm:singleton}). For $n\ge4$ the probability that some singleton RAF exists is exactly $1-(1-p)^{A_\nu}$ with $A_{\spc}=248$ and $A_{\qt}=234$, and every RAF without a singleton witness requires at least two positive catalytic coordinates. Consequently $P^\nu_n(p)=A_\nu p+O_n(p^2)$, so the finite network is linear in $p$ at zero while $\Theta_\nu(\lambda)$ is flatter than every power of $\lambda$. The logarithmic rates of the two iterated limits differ (equation~\eqref{eq:exponents}). \item \textbf{Finite predictions without the approximation cap} (Theorem~\ref{thm:finite}, Section~\ref{sec:examples}). Combining the singleton lower bound with the history bound and the inherited finite catalytic comparison gives \[ 1-(1-p)^{A_\nu}\le P^\nu_n(p)\le\min\{1,\,C_r^\nu(M_np)^r+G_\nu M_{2^{r+1}}p\}, \] which is evaluable in exact rational arithmetic. At $n=16$ and $\lambda=10^{-4}$ this gives $2.16\cdot10^{-7}0$. \item\label{I:seed} \emph{Supplied-seed mass.} Let $C_*=2\cdot7^{64}\cdot81$ be the explicit contour constant of the split source. If $m\ge2$ and $k\ge1$ satisfy \begin{equation}\label{eq:seedtest} C_*(1-b^2)^k\bigl(m(m+1)+1\bigr)\le1, \end{equation} then, at every static openness $a\ge q$ and in every cap $n$, the closure of $F\cup X_L$ with $L=10k$ occupies fewer than $(m-1)M_n/m$ molecule types with probability at most $1/m$. Here $b=q$ for split channels and $b=q/2$ for quotient channels; the latter uses the at-most-two-to-one channel projection and half-openness domination in that analysis. \item\label{I:source} \emph{Finite catalytic comparison.} For $k_{n,m}=(m-1)\lfloor M_n/m\rfloor>6$, near-full static closure at openness $q\le q_{k_{n,m}}(p)$ lower-bounds $P_n^\nu(p)$ up to the mass error of~\ref{I:seed}; and for $n\ge4$, $B\ge2$, \begin{equation}\label{eq:sourceupper} P_n^\nu(p)\le e^\nu_B\bigl(q_{M_n}(p)\bigr)+G_\nu M_Bp . \end{equation} Every RAF contains a catalysed food gateway, so the RAF event is contained in the gateway event; the second term is a union bound over catalysts of length at most $B$ for the $G_\nu$ food gateways, and it retains food-only RAFs. The split adapter with the exact constant $36$ (rather than the coarse constant $68$ of the earlier source) is compiled in this development. \end{enumerate} Condition~\eqref{eq:seedtest} is the contour-ratio form of the supplied-seed estimate: with $z=C_*(1-b^2)^k$ it gives $z/(1-z)\le1/[m(m+1)]$, which is the hypothesis under which the mass theorem delivers error $1/m$. The nontrivial geometric content is inherited; nothing below re-derives it. \section{Effective finite approximation}\label{sec:effective} \subsection{An executable seed selector} For rational $0=Stealth,font=\small,x=1cm,y=1cm] % axis of word length \draw[->] (0,0) -- (12.4,0) node[right] {word length}; \foreach \x/\l in {2/{$2$},4/{$B$},7/{$|w|$},8/{$2B$},10.2/{$|w|+\ell$}} { \draw (\x,0.08) -- (\x,-0.08); \node[below] at (\x,-0.08) {\l}; } % exposed prefix region \fill[black!7] (0.2,0.35) rectangle (7,1.55); \node[anchor=south west,text width=6.4cm] at (0.25,0.4) {\textit{exposed prefix}: all channels with product length $\le|w|$; the atom fixes their marks and the record $w$}; % record word \node[draw,thick,rounded corners=2pt,fill=white,inner sep=3pt] (w) at (7,2.4) {record $w$, $B<|w|\le 2B$}; \draw[->,thick] (7,1.6) -- (w.south); % repair chain \node[draw,rounded corners=2pt,inner sep=2.5pt] (r1) at (8.2,3.5) {$wv_1$}; \node[draw,rounded corners=2pt,inner sep=2.5pt] (r2) at (9.4,3.5) {$wv_1v_2$}; \node[inner sep=1pt] (dots) at (10.4,3.5) {$\cdots$}; \node[draw,rounded corners=2pt,inner sep=2.5pt] (r3) at (11.4,3.5) {$wv$}; \node[draw,thick,rounded corners=2pt,fill=white,inner sep=3pt] (v) at (11.4,2.1) {$w+v$}; \draw[->] (w.north east) -- (r1.west); \draw[->] (r1) -- (r2); \draw[->] (r2) -- (dots); \draw[->] (dots) -- (r3); \draw[->] (r3) -- (v) node[midway,right] {cleave}; \node[anchor=west,text width=4.9cm] at (7.15,1.2) {\textit{repair support}: $\le\ell+1$ fresh channels, products in $(|w|,|w|+\ell]$, disjoint from the prefix}; \draw[decorate,decoration={brace,amplitude=4pt,mirror}] (7.05,-0.55) -- (10.2,-0.55) node[midway,below=4pt] {all repair products live here}; \end{tikzpicture} \caption{The record-and-repair mechanism of Lemmas~\ref{lem:repair} and~\ref{lem:contraction}. Conditioning on a finite exposed prefix through the first own-cap record $w$ leaves the repair coordinates untouched, so the conditional probability that they are all open is at least $a^{\ell+1}$ regardless of how many earlier attempts failed.} \label{fig:repair} \end{figure} \begin{lemma}[Finite record contraction]\label{lem:contraction} For $B\ge2$ and every nonempty target $v$ of length $\ell$, \begin{equation}\label{eq:contraction} \Prob\bigl(F_{2B+\ell}(v)\bigr)\le(1-a^{\ell+1})\,\Prob\bigl(F_B(v)\bigr). \end{equation} \end{lemma} \begin{proof} Partition the escape event beyond $B$ according to the first own-cap record length $M>B$ and the complete configuration of the channels with product length at most $M$. These \emph{prefix atoms} are pairwise disjoint and measurable with respect to finitely many coordinates. On each nonempty atom choose a deterministic record carrier $w$ with $|w|=M$; Lemma~\ref{lem:repair} gives $M\le2B$. Intersect the atom with the event that $v$ is absent from the cap-$B$ closure. This event is also determined by the prefix, so the intersection is a prefix event. The repair support of Lemma~\ref{lem:repair} consists of $s\le\ell+1$ distinct channels with product length above $M$, hence disjoint from the prefix coordinates; conditionally on the prefix its all-open probability is $a^s\ge a^{\ell+1}$. When all repair channels are open, $v$ is generated by cap $M+\ell\le2B+\ell$. Hence on each intersected atom the measure of continued absence of $v$ at cap $2B+\ell$ is at most $(1-a^{\ell+1})$ times the measure of the atom. Finally $F_{2B+\ell}(v)$ is covered by these continued-absence events: escape beyond $2B+\ell$ implies escape beyond $B$, and absence at the larger cap implies absence at cap $B$. Summing over the disjoint atoms, whose intersections with cap-$B$ absence partition $F_B(v)$, gives~\eqref{eq:contraction}. The argument conditions only on a finite exposed configuration; it neither conditions on eventual survival nor asserts independence between failed attempts. \end{proof} \leanrefs{\lean{escaped_missing_contraction}, \lean{quotient_escaped_missing_contraction}, \lean{finite_missing_determined}, \lean{first_record_cap}} \begin{remark} The contraction is the effective replacement for the record-word argument in the limit-law proof, which proves that unbounded closure eventually generates every fixed word but extracts no rate. The rate $1-a^{\ell+1}$ per doubling of the cap is what makes the seed length below usable in a terminating algorithm. It is also why the approximation is uniform on $[q,1]$: the factor only improves as $a$ increases. \end{remark} \subsection{From target repairs to survival} Iterate~\eqref{eq:contraction} along $d_0=2$, $d_{j+1}=2d_j+\ell$; after $r$ steps the residual probability of escaping $d_r$ while missing $v$ at cap $d_r$ is at most $(1-a^{\ell+1})^r$. If $\ell\le L$ then $d_r\le D_r$ and $1-a^{\ell+1}\le1-a^{L+1}$. A union bound over the $M_L=2^{L+1}-2$ words of $X_L$ gives \begin{equation}\label{eq:escape-seed} \Prob\bigl(\text{escape beyond }D_r\text{ and fail to acquire }X_L\text{ by cap }D_r\bigr)\le M_L(1-a^{L+1})^r . \end{equation} No independence between the repairs of different targets is used. \leanrefs{\lean{repeated_record_failure}, \lean{common_cap_target_failure}, \lean{finite_seed_failure}, \lean{exposure_budget}} Let $H_L$ be the event that all of $X_L$ is acquired in the infinite field. The supplied-seed estimate~\ref{I:seed} gives \begin{equation}\label{eq:seed-survival} \Prob(H_L)\le S_\nu(a)+1/m . \end{equation} Here is the finite-to-infinite step, which is where an effective seed replaces an existential one. Fix a length $A$. On the event that the food closure stays inside $X_A$ it has at most $M_A$ types. If $X_L$ has been acquired by cap $n$, the closure of $F\cup X_L$ in cap $n$ is contained in the food closure. For all large $n$, $(m-1)M_n>mM_A$, so acquisition together with boundedness forces the supplied-seed mass failure, whose probability is at most $1/m$. Letting $n\to\infty$ exhausts the finite witnesses of acquisition and letting $A\to\infty$ exhausts bounded closure. Hence $\Prob(H_L\cap\{\text{bounded}\})\le1/m$, which is~\eqref{eq:seed-survival}. Both events live in the same field. \leanrefs{\lean{effective_seed_probability_le_survival}, \lean{effective_quotient_seed_survival}} \begin{proof}[Proof of Theorem~\ref{thm:approx}] Split the event of escape beyond $D_r$ according to whether $X_L$ has been acquired by cap $D_r$. The failure branch has probability at most~\eqref{eq:escape-seed}; the success branch is contained in $H_L$ and has probability at most~\eqref{eq:seed-survival}. Survival implies escape beyond every cap, which is the lower inequality. The closed form $D_r+L=2^r(L+2)$ follows by induction. \end{proof} \subsection{The certified evaluator} \begin{theorem}[Certified rational evaluation]\label{thm:algorithm} For either model there is an explicit terminating algorithm which, given rational $a\in[0,1]$ and rational $\eps>0$, returns a rational interval of width less than $\eps$ containing $S_\nu(a)$. The escape cap computed for a positive rational lower endpoint $q$ controls every real openness $a\ge q$ with the same error budget. \end{theorem} \leanrefs{\lean{splitCertifiedInterval_correct}, \lean{quotientCertifiedInterval_correct}, \lean{splitTotalInterval_correct}, \lean{quotientTotalInterval_correct}, \lean{splitEscapeEval_correct}, \lean{quotientEscapeEval_correct}, \lean{recordIndex_error}} \begin{proof} At $a=0$ return $[0,0]$, using $S_\nu(0)=0$. Otherwise put $m=\lceil4/\eps\rceil+2$, so $1/m\le\eps/4$; compute $L=L_\nu(a,m)$; and let $r$ be the least positive integer with \begin{equation}\label{eq:rtest} 2^{L+1}(1-a^{L+1})^r\le\eps/4 . \end{equation} This is an exact rational test that terminates by geometric decay, the case $a=1$ being immediate. Now evaluate $e=e^\nu_{D_r}(a)$ exactly: the event is determined by the finitely many channels of cap $2D_r$; for each Boolean configuration iterate the one-step closure operator $M_{2D_r}$ times, which computes the full finite closure since each round either adds a type or is stable; sum the weights $a^s(1-a)^{J-s}$ over the configurations witnessing escape, where $J$ is the channel cardinality and $s$ the number of open channels. By Theorem~\ref{thm:approx}, $[e-\eps/2,e]$ contains $S_\nu(a)$ and has width $\eps/2<\eps$; it may be intersected with $[0,1]$ without losing containment. For uniformity compute $L$, $r$ and $D_r$ at the lower endpoint $q$. The seed bound~\ref{I:seed} is uniform for $a\ge q$, and $(1-a^{L+1})^r\le(1-q^{L+1})^r$, so the same budget applies. Every search in this construction terminates by a proof, and the finite-event semantics are proved rather than assumed; no approximation oracle enters. \end{proof} \begin{remark}[Cost]\label{rem:cost} Theorem~\ref{thm:algorithm} is a computability statement in the sense of computable analysis~\cite{weihrauch2000computable}, not a practical interior algorithm. At $m=100$ and $q=1/2$ the selected seed lengths are $L=4830$ (split) and $L=21520$ (quotient); already in the split case a repair error of $0.01$ requires a record index with $\log_2r\approx4843$, after which the recurrence $D_{r+1}=2D_r+L$ and the enumeration of channel fields in cap $2D_r$ are applied. These are the costs of the \emph{proof}, not estimates of $S_\nu$. Section~\ref{sec:history} obtains useful bounds without constructing any such cap, and Section~\ref{sec:finite} obtains useful finite predictions without it. \end{remark} \section{Total-length history bounds}\label{sec:history} A \emph{productive history} is an ordered list of distinct channels $r_1,\dots,r_k$, starting from $C_0=F$, such that each $r_{j+1}$ is enabled by the current available set $C_j$ (one side of the channel is available) and adds at least one new type; $C_{j+1}$ is $C_j$ together with all endpoints of $r_{j+1}$. Productive histories are the combinatorial skeleton of closure. The following structural lemma is what makes counting them efficient. \begin{lemma}[Settled channels and finite histories]\label{lem:settled} After every productive step all endpoints of every previously used channel belong to the current set, and the current set is exactly the full closure of $F$ under the channels used so far. If the open closure reaches a word longer than $2^{r+1}$, then there is a productive history of $r$ distinct open channels; in particular survival supplies such a history for every $r$. \end{lemma} \begin{proof} The first assertion holds initially and persists: after firing an enabled channel its previously missing endpoints are available, so it too is settled, and settled channels stay settled when types are added. The new set is closed under every channel used so far, is reachable from $F$ by those channels, and contains $F$; hence it is their full closure. In particular adjoining a new channel causes no further cascade through earlier channels. In $j$ steps the maximum word length is at most $2^{j+1}$, since a ligation at most doubles length and a cleavage does not increase it. If the current set omits a target that is reachable using all open channels, then some open channel is productive on the current set: otherwise the set is closed under all open channels and contains $F$, hence contains the target. A previously used channel cannot be productive because it is settled, so the productive channel is new. Repeat $r$ times; the length bound prevents reaching the long target early. In the infinite field the target has a finite derivation, so the whole argument takes place in a finite cap; no infinite scheduling is needed. \end{proof} \leanrefs{\lean{settled_insert_closure}, \lean{productive_history_settled}, \lean{productive_history_ordered}, \lean{split_long_target_history}, \lean{quotient_long_target_history}, \lean{split_unbounded_histories}, \lean{quotient_unbounded_histories}, \lean{publication_history_resolution}} \begin{lemma}[Length and cleavage-slot budgets]\label{lem:budget} For a productive history let $T_j=\sum_{w\in C_j}|w|$ and $Q_j=\sum_{w\in C_j}(|w|-1)$. Then for all $j\ge0$ \begin{equation}\label{eq:budgets} |C_j|\le6+2j,\qquad\max_{w\in C_j}|w|\le2^{j+1},\qquad T_j\le2^{j+2}+6,\qquad Q_j\le4\cdot2^j-j . \end{equation} \end{lemma} \begin{proof} Initially $(|C_0|,T_0,Q_0)=(6,10,4)$ and each step adds at most two types. A productive ligation adds one word of length at most $2^{j+2}$, increasing $T$ by at most $2^{j+2}$ and $Q$ by at most $2^{j+2}-1$. A productive cleavage of an available product $w$ adds its factors; their total length is $|w|\le2^{j+1}$ whether or not one factor was already present or the factors coincide, and at least one factor is new, so $T$ increases by at most $|w|$ and $Q$ by at most $|w|-1$. Summing $T_{j+1}-T_j\le2^{j+2}$ and $Q_{j+1}-Q_j\le2^{j+2}-1$ gives the last two bounds. \end{proof} \conventional The point of tracking $T_j$ and $Q_j$ as \emph{sums} rather than as (maximum length)$\times$(cardinality) is the quantitative gain: the number of cleavage candidates is the number of split positions in available words, which is $Q_j$, not $|C_j|\cdot2^{j+1}$. Neither quantity is a physical mass; both count word types. Set $C_0^\nu=1$ and, for $r\ge1$, \begin{equation}\label{eq:Cr} b_j=(6+2j)^2+4\cdot2^j-j\quad(j\ge1),\qquad C_r^\nu=g_\nu\prod_{j=1}^{r-1}b_j , \end{equation} so that $C_1^\nu=g_\nu$, $C_2^{\spc}=32\cdot71=2272$ and $C_2^{\qt}=30\cdot71=2130$. \begin{theorem}[History upper bound]\label{thm:history} For $a\in[0,1]$, $r\ge0$ and either model, \begin{equation}\label{eq:history} S_\nu(a)\le e^\nu_{2^{r+1}}(a)\le\min\{1,\,C_r^\nu a^r\}\le\min\{1,\,(36a)^r2^{r(r-1)/2}\}. \end{equation} The middle inequality also holds when the channels are independently open with nonidentical probabilities all bounded by $a$. \end{theorem} \begin{proof} From $C_0=F$ exactly the $g_\nu$ growth gateways are productive: food-only channels add nothing, and a cleavage of a food word yields food. After $j\ge1$ steps, at most $|C_j|^2$ ordered factor pairs can be ligated and at most $Q_j$ (product, split position) pairs can be cleaved; discarding non-productive candidates or identifying quotient duplicates cannot increase the count. Lemma~\ref{lem:budget} bounds the total by $b_j$. Hence there are at most $C_r^\nu$ legal ordered histories of length $r$, and the family is finite because each prefix has finite branching and the length bound confines every endpoint to a finite word universe. By Lemma~\ref{lem:settled}, escape beyond $2^{r+1}$ is covered by the events that all $r$ channels of some history in this deterministic family are open. A fixed history has $r$ distinct channel identities, so its cylinder event has probability $a^r$; for heterogeneous independent marks it is the product of the $r$ marginals, at most $a^r$. The union bound over the family gives the middle inequality. The histories are enumerated before probabilities are assigned; no claim is made that an adaptively chosen next mark is an unconditioned Bernoulli variable. For the closed envelope, $(6+2j)^2\le32\cdot2^j$ for $j\ge1$ (equality at $j=1$, and $(8+2j)^2\le2(6+2j)^2$ for $j\ge1$ by expanding), so $b_j\le36\cdot2^j$ and $g_\nu\le36$; multiplying gives $C_r^\nu\le36^r2^{r(r-1)/2}$. The case $r=0$ is the trivial bound one. \end{proof} \mixed{the generic union-bound step \lean{history_support_union_bound}, the coefficient envelope \lean{historyBudget_envelope}, and the history extraction of Lemma~\ref{lem:settled}; the polymer census bounding the branching by $b_j$ is conventional} \begin{remark}[Comparison with the sparse-support bound]\label{rem:sparse} The sparse-support flatness bound rests on the observation that $r$ open channels confine closure to length $2^{r+1}$, so escape requires $r$ open channels among the $J_r=R^{\spc}_{2(2^{r+1}+2)}$ channels of the witness cap, giving $S_\nu(a)\le\binom{J_r}{r}a^r$. This is valid, Lean-checked, and numerically useless beyond very small $r$: at $r=2$ the coefficient is $\binom{J_2}{2}=712\,483\,666\,919\,430$ against $C_2^{\spc}=2272$, and $J_r$ grows like $2^{2^{r+2}}$. The settled-history structure removes the dependence on the cap entirely. Figure~\ref{fig:bounds} compares the two envelopes. \end{remark} \leanrefs{\lean{split_sparse_real}, \lean{quotient_sparse_real}, \lean{split_second_coefficient}, \lean{worked_low_openness_bound}} \begin{corollary}[Logarithmic shape and flatness]\label{cor:log} Put $x=\log(1/a)$, $h=\log2$ and $y=x-\log36+h/2$. For $00$ by~\ref{I:law}. Flatness follows directly from~\eqref{eq:history} with $r=d+1$. Since $06$, rational $01$, though clipping at one may then be uninformative. The cap restriction $2B\le n$ keeps the escape event inside the ambient word universe and suffices for the examples. \end{proof} \conventional Increasing $r$ improves the history term at small openness but lets $M_{2^{r+1}}p$ grow doubly exponentially; a useful choice controls the sum. \subsection{Two exact examples at cap sixteen}\label{sec:examples} Take $n=16$, $\lambda=10^{-4}$, $r=2$ and $B=8$, so $M_n=131\,070$, $M_B=510$, $2B=n$, $C_2^{\spc}=2272$ and $C_2^{\qt}=2130$; the channel counts are those of Lemma~\ref{lem:count}. Each model uses its own normalisation $p=16/(10^4R_{16}^\nu)$, that is $p=1/1\,146\,882\,500$ (split) and $p=1/1\,146\,748\,750$ (quotient). Bonferroni's inequality gives the computable lower bound $\Lambda_\nu=A_\nu p-\binom{A_\nu}{2}p^2\le1-(1-p)^{A_\nu}$; write $U_{\mathrm{hist}}=C_2^\nu(M_np)^2$ and $U_{\mathrm{short}}=G_\nu M_Bp$. Table~\ref{tab:finite} displays the three terms. \begin{table}[t] \centering \caption{Finite-source terms at $n=16$, $\lambda=10^{-4}$, each model with its own normalisation. The three probability entries are rounded displays of exact fractions, not outward endpoints; the rigorous outer intervals are~\eqref{eq:finiteexamples}. There is no sampling uncertainty anywhere.} \label{tab:finite} \setlength{\tabcolsep}{5pt} \begin{tabular}{lrrrrr}\toprule Model & $R_{16}^\nu$ & $C_2^\nu$ & $\Lambda_\nu$ & $U_{\mathrm{hist}}$ & $U_{\mathrm{short}}$\\\midrule split & 1\,835\,012 & 2\,272 & $2.162383\cdot10^{-7}$ & $2.967407\cdot10^{-5}$ & $1.600861\cdot10^{-5}$\\ quotient & 1\,834\,798 & 2\,130 & $2.040551\cdot10^{-7}$ & $2.782593\cdot10^{-5}$ & $1.512101\cdot10^{-5}$\\\bottomrule \end{tabular} \end{table} Exact integer cross-multiplication proves \begin{equation}\label{eq:finiteexamples} 2.16\cdot10^{-7}0 . \end{equation} Together with~\ref{I:law}, $S_\nu$ is strictly increasing on $[0,1]$ and maps $[0,1]$ bijectively onto itself. \end{proposition} \begin{proof} Couple all thresholds by independent uniform variables $U_j$ on $[0,1]$, channel $j$ being open at openness $t$ when $U_j\le t$; then survival at $a$ implies survival at $b$, so $S_\nu(b)-S_\nu(a)$ is the probability of surviving at $b$ but not at $a$. Select the growth gateway $\word0+\word{00}\rightleftharpoons\word{000}$ with carrier $w=\word{000}$, and let $\Gamma$ be the event that its variable lies in $(a,b]$ while the variables of the other $g-1$ growth gateways exceed $b$. On $\Gamma$ no growth gateway is open at $a$, so the closure at $a$ is $F$ and survival at $a$ fails; at $b$ the selected gateway is open and $w$ is available. Choose $L\ge4$ such that, at openness $b$, the closure of $F\cup X_L$ is unbounded with probability at least $1/2$; choose a rational $q$ with $00$ one can compute $\delta>0$ such that $|S_\nu(s)-S_\nu(t)|\le\eps$ whenever $s,t\in[0,1]$ and $|s-t|\le\delta$. \end{proposition} \begin{proof} Let $C=g$, so $S_\nu(t)\le1-(1-t)^g\le Ct$. Put $q=\min\{1/4,\eps/(8C)\}$ and run Theorem~\ref{thm:algorithm} at lower endpoint $q$ with tolerance $\eps/2$; this yields a cap with $0\le e(t)-S_\nu(t)\le\eps/4$ for all $t\ge q$, where $e(t)=e^\nu_{D_r}(t)$ has $J$ channel coordinates. Set $\delta=\min\{q,\eps/(4\max\{1,J\})\}$. By the uniform coupling, $|e(s)-e(t)|\le J|s-t|$: the finite escape indicator can change only if some coordinate lies between $s$ and $t$. If $s,t\ge q$ and $|s-t|\le\delta$ then $|S_\nu(s)-S_\nu(t)|\le\eps/4+\eps/4+\eps/4$. If one of them is below $q$, both are at most $2q$, and monotonicity with nonnegativity give $|S_\nu(s)-S_\nu(t)|\le S_\nu(2q)\le2Cq\le\eps/4$. \end{proof} \conventional The critical-window analysis proves continuity of $S_\nu$ on $(0,1]$ and at $0$; the point here is that the modulus is computable, without any lower bound on the openness actually of interest. \begin{proposition}[Inverse brackets]\label{prop:inverse} Given rational $00$, there is a terminating algorithm returning rationals $u{\raggedright\arraybackslash}p{3.4cm}>{\raggedright\arraybackslash}p{2.6cm}>{\raggedright\arraybackslash}p{8.7cm}@{}}\toprule Result & Status & Declarations and scope\\\midrule Lemma~\ref{lem:count} & conventional & Formula checked against enumeration for $n\le9$ by the replay script.\\ Seed selector & Lean source & \lean{seedIndex_spec}, \lean{rational_deficit_bound}, \lean{selected_contour_deficit}.\\ Theorem~\ref{thm:approx} & Lean source & \lean{explicit_split_truncation}, \lean{explicit_quotient_truncation}, \lean{split_uniform_approximation}, \lean{quotient_uniform_approximation}; escape indexed by $K=B-2$.\\ Lemma~\ref{lem:repair} & Lean source & \lean{escape_has_bounded_record}, \lean{finite_record_support}, \lean{quotient_finite_record_support}.\\ Lemma~\ref{lem:contraction} & Lean source & \lean{escaped_missing_contraction}, \lean{quotient_escaped_missing_contraction}: finite prefix atoms, no conditioning on survival.\\ Eqs.~\eqref{eq:escape-seed}--\eqref{eq:seed-survival} & Lean source & \lean{finite_seed_failure}, \lean{effective_seed_probability_le_survival}, \lean{effective_quotient_seed_survival}.\\ Theorem~\ref{thm:algorithm} & Lean source & \lean{splitCertifiedInterval_correct}, \lean{quotientCertifiedInterval_correct}, \lean{splitTotalInterval_correct}, \lean{quotientTotalInterval_correct}; the clipping to $[0,1]$ is a remark.\\ Lemma~\ref{lem:settled} & Lean source & \lean{productive_history_settled}, \lean{settled_insert_closure}, \lean{productive_history_ordered}, \lean{split_unbounded_histories}, \lean{quotient_unbounded_histories}.\\ Lemma~\ref{lem:budget} & conventional & Exhaustive census to depth two in the replay script; \lean{historyBudget_envelope} checks $b_j\le36\cdot2^j$.\\ Theorem~\ref{thm:history} & mixed & Generic step \lean{history_support_union_bound} takes the family count and coverage as premises; the polymer census is conventional. The sparse-coefficient version is expressed in Lean: \lean{split_sparse_real}, \lean{quotient_sparse_real}.\\ Corollary~\ref{cor:log} & mixed & Flatness: \lean{split_low_openness_flatness}, \lean{split_low_intensity_flatness} and quotient counterparts; logarithmic optimisation conventional.\\ Table~\ref{tab:small} & Lean source; replay & \lean{history_certificate_003}, \lean{_004}, \lean{_006}, \lean{_020}; probabilistic meaning via Theorem~\ref{thm:history}.\\ Theorem~\ref{thm:singleton}, Cor.~\ref{cor:exponents} & conventional & Census confirmed at $n=4$ by enumeration; conditional flatness Lean: \lean{conditional_intensity_flatness}.\\ Eqs.~\eqref{eq:sourcecontract}--\eqref{eq:comparison} & Lean source & \lean{splitSourceInterval_correct}, \lean{quotientSourceInterval_correct}, \lean{interval_comparison_error}, \lean{canonical_raf_le_finite_escape_36}.\\ Theorem~\ref{thm:finite} & conventional & Composition of Theorems~\ref{thm:history} and~\ref{thm:singleton} with~\eqref{eq:sourceupper}.\\ Eq.~\eqref{eq:finiteexamples} & Lean source; replay & \lean{split_finite_example_arithmetic}, \lean{quotient_finite_example_arithmetic}, \lean{split_history_coefficient_two}, \lean{quotient_history_coefficient_two}.\\ Section~\ref{sec:regularity} & conventional & Propositions~\ref{prop:strict}--\ref{prop:analytic} and Remark~\ref{rem:conversion}; rational conversion implemented in the replay script.\\\bottomrule \end{tabular} \end{table} \clearpage \bibliographystyle{plain} \bibliography{refs} \end{document}