19.8. Worked examples (checked facts)
Thirteen examples reproduce a headline number (or a theorem) as a #guard, so the
UncertaintyExamples library building under CI is what makes the claims true rather than
asserted — the project's reflection-tests discipline applied to metrology. The first two are the
Stage-0 reference numbers; the next two are the Stage-1 autograd and ladder facts; the next two are
the Stage-2 SSPRC pipeline and its ladder theorems; the last seven are the Stage-3 adequacy carrier,
its per-site theorems, the Stage-3.1 DAG capstone A3′, the Stage-3.2 binary32 Sterbenz, the
Stage-3.3 executable↔spec bridge, the Stage-3.4 Axis-U significance coupling, and the Stage-3.6
direct-simulation closure.
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PropertyKindCalculus.UncertaintyExamples.DegenhardtFictive— the non-linear fictive modelY = (X_1 + X_2^2)\,X_3of Degenhardt (Degenhardt et al., 2025)Johannes Degenhardt, Rainer Tutsch, Xiukun Hu, and Gaoliang Dai (2025). “A practically oriented, efficient alternative to the Monte Carlo method for measurement uncertainty estimation”. Metrologia. 62(2). §3.1, with a normal, a uniform, and a triangular input. The Monte Carlo reference givesE(Y) \approx 11.60,u(Y) \approx 1.70(matching the paper's11.5875,1.691); the reference valueR = f(E(X)) = 11.25, and the gapE(Y) - R = 0.34is the non-linearity signature of theX_2^2term — exactly what the linearized rungs cannot see. The GUM cross-check givesu_c \approx 1.662, visibly under the Monte Carlo value: the linearization drops the curvature, which is the whole motivation for the higher rungs. -
PropertyKindCalculus.UncertaintyExamples.WillinkGaugeBlock— the gauge-block calibration of Willink (Willink, 2005)Robin Willink (2005). “A procedure for the evaluation of measurement uncertainty based on moments”. Metrologia. 42(5). Table 4 (the GUM example H.1), evaluated by the cumulants method: combining the six error variables' variances and fourth cumulants givesu_Y = 33.4\,\mathrm{nm}, excess\gamma_Y = 0.124, and a 99% expanded-uncertainty half-widthh_{0.99} = 87.6\,\mathrm{nm}— 5% narrower than the GUM procedure's 93 nm at the same coverage, because the (mostly negative) fourth cumulants pull the tails of the output toward normal. That narrowing is the difference between the GUM rung and the Willink rung, reproduced as a checked number. -
PropertyKindCalculus.UncertaintyExamples.DegenhardtSensitivity— the Stage-1 autograd bridge on the same fictive kernel: interpreting it at the reverse-mode tape carrier returns the sensitivity coefficients(c_1, c_2, c_3) = (5, 5, 2.25)to machine precision (matching the hand-computed\partial Y/\partial X_iat the means), and feeding them throughgumStdUncreproducesu_c = 1.662exactly — the write-once model differentiated with no rewrite. -
PropertyKindCalculus.UncertaintyExamples.LadderNesting— T1/T2 applied to a concrete all-Gaussian term list overℝ(gum = willink|κ₄=0as a closed proof term,#print axiomsconfirming nosorryAx), together with the executableFloatshadow of the collapse: for normal-only inputs the Willink 95% half-width is exactly1.96\,u_c. -
PropertyKindCalculus.UncertaintyExamples.DegenhardtSsprc— the Stage-2 SSPRC pipeline on the same fictive model (Degenhardt et al., 2025)Johannes Degenhardt, Rainer Tutsch, Xiukun Hu, and Gaoliang Dai (2025). “A practically oriented, efficient alternative to the Monte Carlo method for measurement uncertainty estimation”. Metrologia. 62(2).: 100 systematic samples per input (300 model evaluations against the Monte Carlo reference's 20 000, a factor\approx 67) recoverE(Y) = 11.5875— including the non-linear+0.3375offset the linearized rungs cannot produce — andu(Y) \approx 1.69, closer to the Monte Carlo value than GUM's 1.662; the actual convolution (runConv) reproduces the moment read-off to machine precision. -
PropertyKindCalculus.UncertaintyExamples.SsprcNesting— the T3/T4/T5 ladder theorems applied to two concrete centered distributions overℝ: convolution adds their cumulants (T5), the convolved combined deviation has exactly the Willink cumulants(41, -1186)(T3), and an all-centered (affine) input list yields a centered combined deviation, soE(Y) = R(T4) — with#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AdequacySwamping— the executableAdequacycarrier on two write-once kernels:bias + xwith a small input uncertainty is flagged swamped under a large accumulator (10^8, where\tfrac12\,\mathrm{ulp}_{32} = 4 > 1) and certifies clean under a small one (100);a − bof near-equal uncertain operands is flagged catastrophic cancellation (relative uncertainty ≥ 100%) and certifies clean when the operands are well separated — the same kernel, checked for free at each configuration. -
PropertyKindCalculus.UncertaintyExamples.AdequacyLadder— the adequacy theorems A1 (absorption,\mathrm{round}_8(80+1) = 80), A2 (Sterbenz,3 - 2of twoFLX 24numbers isFLX 24), and A3 (the verdict biconditional) applied to concrete values overℝ, with#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AdequacyDag— the Stage-3.1 capstone A3′ instantiated on concrete model DAGs (a three-input accumulator, an add/sub variant, a deeper five-input tree): theFP32measurand's variation over an input box equals theℝone up to the DAG-additive rounding budget, and exactly when no site rounds (flag-free) — again with#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AdequacySterbenz32— the Stage-3.2 A2 lift to the genuine binary32 format:\mathrm{round}_{32}(u - v) = u - vand(a - b).\mathrm{val} = a.\mathrm{val} - b.\mathrm{val}for near-equal representable binary32 values (so thesub32_within_half_ulpbound collapses to zero), tied back to the self-containedFLX 24fact — with#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AdequacyExecBridge— the Stage-3.3 executable↔spec bridge: the ULP queryulpExp?and absorption testabsorbsrun on concrete float32 bit patterns (#guard: at2^{25}the ULP is4, so a perturbation of1is absorbed and4is not; at10^8the ULP is8, so1is absorbed and8is not), whileexec_verdictproves that whenever the kernel reports absorption the exact real sum rounds back under\mathrm{round}_{32}— the computed verdict equal to the specified one, with#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AdequacyCoupling— the Stage-3.4 kind-typed coupling: oneanalyzeQon the Degenhardt descriptors yields kinded contributions(c_i u_i) = (1.0, 1.30, 0.28)at\mathrm{measurandY}whose quadrature reproduces the GUM combined uncertaintyu_c = 1.662359exactly, and certifies the model adequate at that scale;#check_failureprobes make the metrological conflations (sensitivity↔uncertainty, heterogeneous quadrature,CouplingResultQfield swap) type errors; and a10^8-accumulator swamps a contribution (one absorption), withcontribution_absorbed_at_scaleapplying the A3 verdict at that scale,#print axiomsconfirming nosorryAx. -
PropertyKindCalculus.UncertaintyExamples.AutogradDirectSim— the Stage-3.6 closure instantiated concretely: the vectorization homomorphisms at a 3-vector shape; the compiled product graphx_0 \cdot x_1withdirect_PR_soundness_compiled(the runtime dense reverse pass succeeds and its input-prefix realises the adjoint of the Fréchet derivative) and its inhabited forward simulation; an eager two-leaf/mulruntime tape whose shape-total-closure hypothesis is discharged constructor by constructor; and, via the eager-provenance addendum,EagerBuildswitnessing that runtime tape withdirect_PR_soundness_eagergiving the endpoint on it — no compilation involved — with#print axiomspinning the classical trio only.