% % % % % \section{Computer-Assisted Parts, Data, Validation and Lean}\label{app:cert} Every computer-assisted result consists of a written reduction, a theorem proved in the text, and an explicit finite predicate checked over a finite set. Table~\ref{tab:ca} lists these items, followed by the exact computations quoted as parameters or as results of exhaustive searches in a stated scope. The data (check vectors, designs, window systems, tables, certificates) are archived, each item with a verifier that reads only the data files, never the search programs. Searches (over check vectors, for window systems, SAT solvers) only produced the data (Section~\ref{sec:conventions}). \begin{table}[tp] \centering \footnotesize \caption{The computer-assisted items: the finite check, its scope, and the independent verification. Below the middle rule: exact computations that are quoted but are not part of a proof of a theorem, proposition or corollary.} \label{tab:ca}\label{tab:checks} \setlength{\tabcolsep}{3pt} \begin{tabular}{@{}>{\raggedright\arraybackslash}p{0.18\textwidth}>{\raggedright\arraybackslash}p{0.30\textwidth}>{\raggedright\arraybackslash}p{0.22\textwidth}>{\raggedright\arraybackslash}p{0.26\textwidth}@{}} \toprule result & finite check & scope & verified by\\ \midrule Tab.~\ref{tab:residue} (Thm.~\ref{thm:residue}, Cor.~\ref{cor:korobov}) & exact $\ljit(\Lambda_v)^2$ by enumeration of $\Lambda_v$ in a box; for entries marked E, all check vectors $(x,-1)$ & the $18$ rows, the Korobov column & three programs; a brute force at $s=4$, $p=1009$\\ Thm.~\ref{thm:block}(c) below its proof range & exact $\LB(F)$ of $U^*_4$, $U^*_5$ (Lem.~\ref{lem:cert}, $j=1$) & every prime $7\le p\le109$ ($s=4$), $19\le p\le109$ ($s=5$) & two programs; a third at $24$ of them; Lean kernel\\ Thm.~\ref{thm:block}(d) & hypothesis of Lem.~\ref{lem:signclass}; exact $\LB(F)$ below its range & $s=4,\dots,7$; primes as in the proof & two programs; Lean kernel in part (App.~\ref{app:lean})\\ Prop.~\ref{prop:primepower} & exact $\beta_q(k)$; for $s\le3$ for every $f$, $k$ & the $26$ rows of Tab.~\ref{tab:primepower} & two or three programs; Lean kernel\\ Thm.~\ref{thm:p7} & no vanishing combination in $\LB(\mathsf w)$ & $5$ classes of steps, $\le7^6$ combinations each & three programs (App.~\ref{app:p7}); Lean kernel\\ Thm.~\ref{thm:A3} & $\mathcal P(p_0)$, $p_0=19\,673\,600$ & one exact evaluation & second evaluation of $\mathcal P$; Lean kernel\\ Rem.~\ref{rem:A3range} & hypotheses of Prop.~\ref{prop:steer} and Lem.~\ref{lem:W}, crosses in $\F_p$ & $1\,035\,877$ primes in $[3\cdot10^6,1.97\cdot10^7]$ & checker with its own exact window bound\\ thresholds after Thm.~\ref{thm:A}, $s=4,5$ (not part of its proof) & $\mathcal P(p_0)$ & one exact evaluation each & spot check above $p_0$; Lean kernel\\ Cor.~\ref{cor:HB17} & conditions of Thm.~\ref{thm:HB}, coverings as set identities & $715$ primes, $3677
2^s$, separation bound at every prefix $P_{sK-1}$, bounded mesh ratio). \subsection{The Small-Base Bounds: Explicit Close Pairs}\label{app:sharp} The certified bounds of Theorems~\ref{thm:S3}, \ref{thm:K4} and~\ref{thm:S4} are far below the exact separations of Table~\ref{tab:frames}, but this is not a weakness of the bound (for Theorem~\ref{thm:K4} by two programs, for the others by one). A carry of length $l$ exists only from level $K=l$ on, and the binding steps involve long carries, which the computable prefixes do not contain. The next lemma turns a binding configuration into a pair of points. \begin{lemma}[Explicit close pairs]\label{lem:witness} Let the offset map be the same at every level, and fix $j$, a step $e$, carry lengths and carry digits of the moving coordinates, with the changes $\sigma_c$ of Lemma~\ref{lem:cert}. At a level $K$ at least the largest carry length, the cells with this carry pattern are given by prescribing some of their finest digits. If the affine map from the remaining cell digits to the geometric digits $(R_c)_c\in\F_q^{sj}$ is onto, then $\sep{P_{sK}}\le\bigl(\sum_c(f_j(e_c,\sigma_c)+2q^{-j})^2\bigr)^{1/2}$. \end{lemma} \begin{proof} Choose $R^*_c$ attaining the minimum in $f_j(e_c,\sigma_c)$ and, by surjectivity, a cell $n$ with the carry pattern and $R(n)=R^*$. The neighbour $n+e$ has the geometric digits $R^*_c\oplus\sigma_c$, so by (\ref{eq:cellunits}) the two points differ in coordinate $c$ by at most $f_j(e_c,\sigma_c)+2q^{-j}$ cell units. \end{proof} For Theorem~\ref{thm:K4} the binding configuration (carry lengths $9$ and $16$) is realisable at $K=18$, where the map has full rank, and gives two points of $P_{54}$ at distance $0.112940$ cell units. So $0.112930\le\inf_K\sep{P_{3K}}\le0.112940$ (computer-assisted), to $0.01\%$. Likewise $\sep{P_{225}}\le0.05616$ for Theorem~\ref{thm:S3} and $\sep{P_{256}}\le0.03176$ for Theorem~\ref{thm:S4}. Larger constants in these frames need other multipliers, not better bounds. As binary sequences, the prefixes of $2^M$ points of Theorem~\ref{thm:K4} have base-$2$ quality parameter $t\le3$ for $M\le18$, $t=0$ at every $M=6K$; those of Theorem~\ref{thm:S4} have $t\le4$ for $M\le20$ (computations); the three- and four-dimensional Sobol' sequences have $t=1$ and $3$. \begin{remark}[Why these bases]\label{rem:height} Heuristically: in a Kummer frame $\coef{n}\tau^{-b}=\prod_i\binom b{n_i}$ over the base-$q$ digits $n_i$ of $n$. For $q=3$ only $b\le1$ occurs, and for $q=4$, $(1+x)^2=1+x^2$ keeps all coefficients in $\{0,1\}$, so the automata stay small; over $\F_5$ the coefficients $2$, $3$ appear, and the symmetric scrambles we screened had over $300$ response columns per coordinate at $j=3$, without positive bound. \end{remark}