Substrate Geometry
Computer-assisted interval computation / private preview
AConvex range of a spherical-harmonic perturbationHAND PROOFBConvexity thresholds for 27 harmonic bodiesCOMPUTER-ASSISTEDCEquilibrium counts for the m = 1 harmonic bodiesCOMPUTER-ASSISTEDD1Sloan shape 2: upper bound on the convex rangeHAND PROOFD2Sloan shape 2 is strictly convex for beta up to 0.03550477COMPUTER-ASSISTEDD3Sloan shape 2 has the origin as centroid and exactly two equilibriaHAND PROOFD4Sloan shape 1: upper bound on the convex rangeHAND PROOFD5Sloan shape 1 is strictly convex and mono-monostatic for beta up to 0.03229670385COMPUTER-ASSISTEDE1Phase-1 body: strictly convex2 METHODSE2Phase-1 body: exactly one stable and one unstable equilibrium2 METHODSF1Phase-1 gradient floorCOMPUTER-ASSISTEDF2Phase-1 Hessian at the equilibria: flat in one direction, steep in the otherCOMPUTER-ASSISTEDF3How much shape error Phase-1 toleratesCOMPUTER-ASSISTEDF4Is Phase-1 close to the best this family can do?EXPLORATORYG1Phase-1 equilibrium count as a replayable recordCOMPUTER-ASSISTEDG2Single-harmonic m=1 counts from the same checkerCOMPUTER-ASSISTEDG3Convexity of radial bodies, checked against the published thresholdsCOMPUTER-ASSISTEDG4Mesh trials: how much shape error a printed gomboc can takeEXPLORATORYG5A nearest-neighbour scan miscounts a flat bodyEXPLORATORYAConvex range of a spherical-harmonic perturbationHAND PROOFBConvexity thresholds for 27 harmonic bodiesCOMPUTER-ASSISTEDCEquilibrium counts for the m = 1 harmonic bodiesCOMPUTER-ASSISTEDD1Sloan shape 2: upper bound on the convex rangeHAND PROOFD2Sloan shape 2 is strictly convex for beta up to 0.03550477COMPUTER-ASSISTEDD3Sloan shape 2 has the origin as centroid and exactly two equilibriaHAND PROOFD4Sloan shape 1: upper bound on the convex rangeHAND PROOFD5Sloan shape 1 is strictly convex and mono-monostatic for beta up to 0.03229670385COMPUTER-ASSISTEDE1Phase-1 body: strictly convex2 METHODSE2Phase-1 body: exactly one stable and one unstable equilibrium2 METHODSF1Phase-1 gradient floorCOMPUTER-ASSISTEDF2Phase-1 Hessian at the equilibria: flat in one direction, steep in the otherCOMPUTER-ASSISTEDF3How much shape error Phase-1 toleratesCOMPUTER-ASSISTEDF4Is Phase-1 close to the best this family can do?EXPLORATORYG1Phase-1 equilibrium count as a replayable recordCOMPUTER-ASSISTEDG2Single-harmonic m=1 counts from the same checkerCOMPUTER-ASSISTEDG3Convexity of radial bodies, checked against the published thresholdsCOMPUTER-ASSISTEDG4Mesh trials: how much shape error a printed gomboc can takeEXPLORATORYG5A nearest-neighbour scan miscounts a flat bodyEXPLORATORY
RESULTS LEDGER

Every result, with its tier and its limits

Read results.json for the same facts as data. A row without a source file, or without a not-covered line, cannot be added.

HAND PROOF

A proof written out on paper. A computer may have checked the numbers, but the argument does not depend on one.

2 METHODS

An interval-arithmetic computation, repeated by a second method that shares no chart, symmetry reduction or polar cap with the first, over the whole statement.

COMPUTER-ASSISTED

A statement about ball-arithmetic enclosures, backed by a script and log. Where a second method covers part of it, the row says exactly how much.

EXPLORATORY

A float scan. It shows where to look. It is not a certificate and is never cited as one.

showing 19 of 19
ATheorem AHAND PROOFNote, not yet posted

Convex range of a spherical-harmonic perturbation

Let g be a spherical polynomial of degree at most L with max |g| = 1. The body r = 1 + eps g is strictly convex for every eps < 1 / (L^2 + 1), and the constant cannot be improved: a sectoral harmonic reaches it.

Numbers
Sharp threshold1 / (L^2 + 1)
Key inputBernstein-Riesz inequality along great circles
Method

Bernstein's inequality along great circles bounds the second derivative of g by L^2 max|g|; inserting that into the convexity matrix M = r^2 sigma + 2 grad r (x) grad r - r Hess r gives positive definiteness.

Second method

None for this row.

What is not covered
  • A literature check for prior statements of this inequality is still open.
  • It bounds the convex range from below only; Table B shows the true range is larger for non-sectoral bodies.
Evidence
convex_range_note/main.tex
BTable BCOMPUTER-ASSISTEDNote, not yet posted

Convexity thresholds for 27 harmonic bodies

For each of the 27 bodies Y_l^m with 2 <= l <= 7, an interval bracket of the largest amplitude that keeps the body strictly convex, with relative width at most 0.5 percent.

Numbers
Bodies27
Non-sectoral, eps0 (l^2+1)1.077 to 1.472
Sectoral, eps0 (l^2+1)0.996 to 1.002
Max bracket width0.5 %
Method

Branch and bound with a centered form from forward-mode automatic differentiation, in ball arithmetic.

Second method

Cartesian cube-face method on three bodies: Y33, Y44, Y31. The other 24 have the primary method only.

What is not covered
  • 24 of the 27 brackets have no second method.
  • l above 7.
Evidence
convex_range_note/repro/
convex_range_note/repro/table_final.json
CTheorem CCOMPUTER-ASSISTEDManuscript, not yet posted

Equilibrium counts for the m = 1 harmonic bodies

For l = 2, 3, 4, 5, 6, 7 and every amplitude from just above 0 to the stated upper end, the body has exactly S = U = l stable and unstable equilibria and H = 2l - 2 saddles, all nondegenerate, with none in the polar caps.

Numbers
l = 2eps above 0 to 0.1994, (2, 2, 2)
l = 3eps above 0 to 0.1062, (3, 3, 4)
l = 4eps above 0 to 0.0668, (4, 4, 6)
l = 5eps above 0 to 0.0452, (5, 5, 8)
l = 6eps above 0 to 0.0327, (6, 6, 10)
l = 7eps above 0 to 0.02465, (7, 7, 12)
Method

Amplitude intervals are split into tiles. On each tile the centroid and the equilibrium conditions are evaluated with interval amplitude; Krawczyk uniqueness boxes and exclusion boxes cover the sphere. Below about 60 percent of the range the same is done on the rescaled potential (rho - 1) / (2 eps), which stays smooth down to eps = 0.

Second method

Point checks by the cube-face method at one amplitude each for l = 3, 4, 5, 6, 7 (l = 6 and 7 inside the rescaled cover); inconclusive for l = 2. These are not interval covers.

What is not covered
  • l = 8 and above.
  • m = 0 and m of 2 or more.
  • Second method inconclusive for l = 2 (equilibria on chart seams); only point checks, no second-method cover of the rescaled tiles.
  • Stable and unstable labels in the second method are floats, checked through S - H + U = 2.
Evidence
flagship_repro/m1/m1_interval.py
flagship_repro/m1/m1_independent.py
flagship_repro/m1/m1_interval_Y71_merged.json
flagship_repro/m1/m1_small_eps.py
D1Closed formHAND PROOFManuscript, not yet posted

Sloan shape 2: upper bound on the convex range

At the point of least radius the Gaussian curvature of Sloan's second shape is an explicit function of beta and is negative on (beta*, 0.2474), with beta* = 0.0355047718919948. The convex range stated in the original note (beta up to 0.17) is therefore not convex.

Numbers
beta*0.0355047718919948
Stated in the notebeta <= 0.17
Method

Direct evaluation of the curvature at (theta, phi) = (pi/2, pi), where R^4 = 1 - 4 beta.

Second method

None for this row.

What is not covered
  • Independently re-derived with symbolic algebra on 2026-11-07: the root matches the closed form to 33 digits. A human reading of the derivation is still wanted.
Evidence
scoping/FLAGSHIP-MANUSCRIPT-2026-11-06.md section 5.2
scoping/SLOAN-CONVEXITY-THRESHOLD-CLOSED-FORM-2026-11-02.md
flagship_paper/verify_beta_star.py
D2Theorem DCOMPUTER-ASSISTEDManuscript, not yet posted

Sloan shape 2 is strictly convex for beta up to 0.03550477

K > 0 on the whole surface for every beta in [0, 0.03550477]. The remaining gap to beta* is 1.9e-9.

Numbers
Primary range0 to 0.03550477
Second method range0 to 0.0355047
Gap to beta*1.9e-9
Boxes (primary)26,535,337 + 2,797
Method

Compact radial-graph chart plus polar caps, centered form from automatic differentiation.

Second method

Cartesian cube-face method over beta from 0 to 0.0355047. A third route (convexity matrix in (t, psi, beta)) covers the whole range up to 0.0355047718 as a replayable record of the box search, re-validated by a separately written checker; the gap to beta* is 9.2e-11.

What is not covered
  • The last 7e-8 of the range by the cube-face method (the third route covers it).
  • The single value beta = beta*.
Evidence
flagship_repro/sloan/certify_fine.py
flagship_repro/sloan/gap_fine_b03550477.log
flagship_repro/sloan/sloan_audit.py
D3DerivationHAND PROOFManuscript, not yet posted

Sloan shape 2 has the origin as centroid and exactly two equilibria

For every 0 < beta < 1/4 the centroid is the origin (the integral of sin^3 t exp(i eta) vanishes) and the radius function has exactly two nondegenerate critical points, a minimum at (pi/2, pi) and a maximum at (pi/2, 0). With strict convexity these are the stable and unstable equilibria.

Numbers
Equilibria2, nondegenerate
Valid for beta0 < beta < 1/4 (centroid, critical points)
Method

Hand derivation of the centroid integral and the gradient of R on the sphere.

Second method

None for this row.

What is not covered
  • Re-derived with no algebra errors found. A human reading is still wanted.
  • The original note states these facts without derivation.
Evidence
scoping/FLAGSHIP-MANUSCRIPT-2026-11-06.md section 5.4
D4Closed formHAND PROOFManuscript, not yet posted

Sloan shape 1: upper bound on the convex range

At the point of least radius the Gaussian curvature of Sloan's first shape is (125 beta^2 - 35 beta + 1) / (1 - 4 beta)^(5/2), negative between the roots (7 - sqrt 29) / 50 = 0.03229670385730 and 0.24770329. The convex range stated in the original note (beta up to 0.15) is therefore not convex, too large by a factor of about 4.6.

Numbers
beta*0.03229670385730
Stated in the notebeta <= 0.15
Method

Symbolic curvature of the implicit surface at (theta, phi) = (pi/2, -pi/2), where R^4 = 1 - 4 beta; the sign is checked by ball arithmetic on [0.0324, 0.15] and [0.0001, 0.032].

Second method

None for this row.

What is not covered
  • One point of the surface: this refutes the stated range. Convexity below the root and the equilibria of this shape are the subject of D5.
  • A human reading of the derivation is still wanted.
Evidence
scoping/FLAGSHIP-MANUSCRIPT-2026-11-06.md section 5.5
flagship_repro/sloan/shape1_pole_K.py
D5TheoremCOMPUTER-ASSISTEDManuscript, not yet posted

Sloan shape 1 is strictly convex and mono-monostatic for beta up to 0.03229670385

The convexity matrix of Sloan's first shape is positive definite on the whole sphere, poles included, for every beta in [0, 0.03229670385]. With the origin as centroid and exactly two nondegenerate critical points of the radius, the body has one stable and one unstable equilibrium. The remaining gap to the closed-form limit is 7.3e-12.

Numbers
Range covered0 to 0.03229670385
Gap to beta*7.3e-12
Boxes11,629,511 nodes, 5,814,756 leaves
Smallest lower bound of det M1.2e-16
Method

Branch and bound in ball arithmetic on M11 > 0 and det M > 0 over (t, psi, beta), with psi = p - 5t. The matrix is polynomial in sines and cosines, so the poles, where the phase 5t makes the body only C^1, are covered by the same boxes. Centroid and the two equilibria follow by hand.

Second method

The matrix agrees in sign with the curvature of the implicit surface (automatic differentiation) at 6000 of 6000 random points, 667 of them with K < 0. This is a formula check, not a second box computation. A separately written checker replays the box-search record.

What is not covered
  • The last 7.3e-12 below the closed-form limit.
  • A negative control: the same program proves det M < 0 on boxes for beta in [0.0324, 0.0326].
  • A human reading of the derivation of the matrix is still wanted.
  • The surface is only C^1 at the poles; local convexity there uses the standard fact that a C^1 surface with positive definite M at every neighbouring point is convex.
Evidence
flagship_repro/sloan/shape1_convexity_cert.py
flagship_repro/sloan/shape1_M_vs_implicit.py
flagship_repro/sloan/shape1_cert_runs.log
E1Theorem E12 METHODSManuscript, not yet posted

Phase-1 body: strictly convex

The Phase-1 body, r^4 = 1 + 4 beta sin t cos(p - eta - a1 sin eta) with beta = 23149/10^6 and a1 = 234433/10^6, has K > 0 on the whole surface.

Numbers
Primary boxes1,089 + 367 caps
Second method boxes119,142
Parametersexact rationals
Method

Compact chart plus polar caps with plain interval evaluation.

Second method

Cube-face Cartesian method with a centered form, no chart, symmetry or cap shared with the first. Full coverage of the surface.

What is not covered
  • Only positivity of K is established, not a stated margin.
Evidence
flagship_repro/phase1/phase1_convexity.py
flagship_repro/phase1/phase1_audit.py
flagship_repro/phase1/phase1_audit.log
E2Theorem E22 METHODSManuscript, not yet posted

Phase-1 body: exactly one stable and one unstable equilibrium

With its centroid enclosed by exact integrals (c_x = -0.0026955695464916...), the Phase-1 body has S = U = 1 and H = 0: exactly two equilibria, both nondegenerate.

Numbers
Centroid c_x-0.00269556954649164614590662...
Centroid widthbelow 1e-40
Counts (S, U, H)(1, 1, 0)
Jacobian determinants0.042 and 0.047
Exclusion boxes (second method)51,346
Method

Interval counter with Krawczyk uniqueness boxes on the compact chart and the polar caps.

Second method

Cartesian implicit surface on six cube faces, equilibrium condition N x (x - c) = 0, Krawczyk uniqueness in two boxes and an exclusion proof elsewhere.

What is not covered
  • The parameters come from an earlier optimiser run that does not reproduce from the text of the earlier preprint. The object certified here is the one with these exact parameters.
Evidence
flagship_repro/phase1/phase1_centroid.py
flagship_repro/phase1/phase1_count.py
flagship_repro/phase1/phase1_count_audit.py
F1MarginCOMPUTER-ASSISTEDManuscript, not yet posted

Phase-1 gradient floor

Away from the two equilibria the round-metric gradient of the squared centroid distance has a computer-assisted floor m(r0) outside caps of radius r0.

Numbers
r0 = 0.42.3e-3
r0 = 0.21.2e-3
r0 = 0.16.2e-4
r0 = 0.053.0e-4
r0 = 0.021.3e-4
r0 = 0.0052.5e-5
Method

Forward-mode automatic differentiation in ball arithmetic, bulk chart plus both polar caps in a stereographic chart.

Second method

None for this row.

What is not covered
  • Phase-1 only; no other body has margins.
  • No second method.
Evidence
flagship_repro/margins/phase1_robust.py
flagship_repro/margins/robust_sweep.log
F2MarginCOMPUTER-ASSISTEDManuscript, not yet posted

Phase-1 Hessian at the equilibria: flat in one direction, steep in the other

At the stable equilibrium the Hessian eigenvalues lie in [0.0066, 1.741]; at the unstable one in [-1.596, -0.0068]. The landscape is flat in one direction and steep in the other, with a condition number near 260.

Numbers
Stable eigenvalues0.0066 to 1.741
Unstable eigenvalues-1.596 to -0.0068
Condition numberabout 260
Definite on the box forr0 <= 0.005
Method

Coordinate Hessian enclosed on boxes around each equilibrium.

Second method

None for this row.

What is not covered
  • Definiteness is not established on the box at r0 = 0.01.
  • No second method.
Evidence
flagship_repro/margins/phase1_hessian.py
flagship_repro/margins/phase1_hessian.json
F3PropositionCOMPUTER-ASSISTEDManuscript, not yet posted

How much shape error Phase-1 tolerates

If a radial perturbation of degree at most k has amplitude a below the stated bound, the perturbed body is still strictly convex and still has exactly one nondegenerate minimum and one nondegenerate maximum of the squared centroid distance. The bounds are sufficient conditions, not sharp ones.

Numbers
k = 1a <= 2.0e-6
k = 5a <= 1.1e-6
k = 10a <= 6.7e-7
k = 50a <= 1.4e-7
Convexity margin of perturbed bodylambda_min(M) >= 0.0766
Method

A perturbation argument on the two boxes, with every constant enclosed in interval arithmetic: gradient bound, Hessian bound, centroid shift, Bernstein-Riesz.

Second method

None for this row.

What is not covered
  • A human reader of the proposition and its constants is still wanted.
  • Phase-1 only.
  • Not a physical tolerance for any material.
Evidence
flagship_repro/margins/prop_constants_cert.py
flagship_repro/margins/prop_gr_cert.py
flagship_repro/margins/prop_tolerance_cert.py
flagship_repro/margins/prop_convexity_cert.py
F4ScanEXPLORATORYManuscript, not yet posted

Is Phase-1 close to the best this family can do?

Over a grid of one extra Fourier harmonic added to Sloan's phase, the best gradient robustness among convex (1,1,0) bodies is about 2.9e-3 against 1.6e-3 for Phase-1, and the best Hessian margin about 9.6e-3 against 6.6e-3. Re-optimising inside this family gains less than a factor of two.

Numbers
Best gradient robustness (scan)2.9e-3
Phase-1 gradient robustness1.6e-3
Best Hessian margin (scan)9.6e-3
Phase-1 Hessian margin6.6e-3
Method

Grid candidates refined by a continuous root solve. A first version that counted grid extrema reported 21 minima and 19 maxima on flat ridges for a body with exactly one of each; it was discarded.

Second method

None for this row.

What is not covered
  • A coarse float scan of one phase function. It is not a bound on all gombocs.
Evidence
flagship_repro/margins/robust_map.py
flagship_repro/margins/robust_map2.py
G1Software resultCOMPUTER-ASSISTEDSoftware, not yet released

Phase-1 equilibrium count as a replayable record

For every centroid in a stated box around the Phase-1 centroid, the squared centroid distance of the Phase-1 body has one minimum, one maximum and no saddle, and a second, independent program re-evaluates the whole record.

Numbers
Result (S, U, H)1, 1, 0
Euler characteristic2
Leaves16053 (16051 Empty, 2 One)
Search and replay17 s and 5 s
Replay in a browser28.9 s (VALID, on a busy machine); a copy claiming 2 stable positions is rejected
Centroid box half-width1e-24
Method

The sphere is covered by boxes on the six faces of a cube. A box is Empty when the gradient of the squared centroid distance is provably nonzero for every centroid in the box, and One when Krawczyk's operator shows a single critical point, typed by the interval Hessian. The search is untrusted; a short separate checker re-evaluates every box in ball arithmetic and recomputes the totals.

Second method

None for this row.

What is not covered
  • Strict convexity is an input; row E1 covers it.
  • The centroid box is the paper's printed value widened by 1e-24, not an enclosure computed here.
  • The checker is a short program, not a formally verified one.
  • Nothing is claimed about a printed object.
Evidence
software/eqcert/certificates/phase-1_count_exact_point.json
software/eqcert/src/eqcert/check_count.py
software/eqcert/tests/test_count_certificates.py
scoping/SOFTWARE-AND-TRIALS-DATASHEET-2026-11-08.md
G2Software resultCOMPUTER-ASSISTEDSoftware, not yet released

Single-harmonic m=1 counts from the same checker

At one small amplitude for each degree l = 2 to 5, the body r = 1 + e P_l'(u_z) u_x has (l, l, 2l-2) stable, unstable and saddle positions, the class reported in row C.

Numbers
l = 2, e = 1/50(2, 2, 2), 2688 leaves
l = 3, e = 1/100(3, 3, 4), 4509 leaves
l = 4, e = 1/200(4, 4, 6), 24622 leaves
l = 5, e = 1/400(5, 5, 8), 140313 leaves
Method

The same cover and checker as row G1, with the radial formula of the body in place of the Sloan form and an exact rotation of the cube so that no critical point lies on a cube edge (the l = 2 body has its extrema exactly on edges).

Second method

None for this row.

What is not covered
  • One amplitude for each degree; row C covers the whole range.
  • Degrees 6 and above were not run here.
  • The centroid box is exact quadrature padded by 1e-12, not an enclosure.
  • Convexity of these bodies comes from row G3 and Table B, not from this record.
Evidence
software/eqcert/tests/test_harmonic_counts.py
software/eqcert/src/eqcert/check_count.py
software/eqcert/src/eqcert/count_cert.py
scoping/SOFTWARE-AND-TRIALS-DATASHEET-2026-11-08.md
G3Software resultCOMPUTER-ASSISTEDSoftware, not yet released

Convexity of radial bodies, checked against the published thresholds

A convexity matrix for any radial body, evaluated on the cube-face charts, changes sign at the thresholds of Table B (l = 2, 3, 4, m = 1), and strict convexity of those bodies is shown by interval computation for every amplitude up to a stated fraction of the threshold.

Numbers
Sign check l = 2+0.00042 at 0.99 of the threshold, -0.00113 at 1.01
Sign check l = 3+0.00213 at 0.99, -0.00254 at 1.01
Sign check l = 4+0.00301 at 0.99, -0.00624 at 1.01
Convex up to, l = 2e = 0.106341 (80 percent), 612392 leaves, replay 80 s; e = 0.12628 (95 percent), 2588916 leaves, replay 292 s
Convex up to, l = 3e = 0.041712 (80 percent), 233540 leaves, replay 34 s
Convex up to, l = 4e = 0.020245 (80 percent), 138220 leaves, replay 23 s
Method

Convexity of a radial graph is positive definiteness of M = r^2 g + 2 dr (x) dr - r Hess r on the tangent plane. The matrix is built from the second-order jets of the unit vector in each cube-face chart, and the amplitude is an interval, so one record covers a whole range of amplitudes. The matrix is cross-checked against automatic differentiation of the implicit surface (the sign of its determinant agrees with the Gauss curvature at every checked point) and against the thresholds of Table B.

Second method

None for this row.

What is not covered
  • Up to 95 percent of the lower bracket for l = 2 and 80 percent for l = 3 and 4; the last few percent need a much larger search.
  • The hand derivation of the matrix is not machine checked; it is cross-checked against automatic differentiation and the published thresholds.
  • Only the m = 1 harmonic bodies were run.
Evidence
software/eqcert/src/eqcert/check_radial_convex.py
software/eqcert/tests/test_radial_convexity.py
software/eqcert/certificates/harmonic-l2-m1_convex_e_0_0.12628.json
software/eqcert/certificates/harmonic-l3-m1_convex_e_0_0.041712.json
software/eqcert/certificates/harmonic-l4-m1_convex_e_0_0.020245.json
scoping/SOFTWARE-AND-TRIALS-DATASHEET-2026-11-08.md
G4Floating-point trialEXPLORATORYSoftware, not yet released

Mesh trials: how much shape error a printed gomboc can take

In 20 random smooth radial perturbations per level of a Phase-1 mesh, most meshes keep one stable and one unstable position at a relative error of 1e-4 and most do not at 1e-3.

Numbers
Phase-1, error 1e-520 of 20 keep one of each
Phase-1, error 1e-418 of 20 (6-step test), 20 of 20 (10-step test)
Phase-1, error 1e-34 of 20 and 5 of 20
Phase-1, error 3e-3 and 1e-20 of 20; 9 of 20 meshes still convex at 1e-2
Sloan shape 2 at the edge of its convex range20 of 20 at 1e-5, 17 of 20 at 1e-4, 0 of 20 from 1e-3
Scale1e-4 of the radius is about 5 micrometres on a 100 mm body
Method

A smooth random radial error of sup-norm eps is added to the mesh, the mesh centroid is recomputed, and minima and maxima of the distance from the centroid are counted within a neighbourhood of 6 and of 10 grid steps. Convexity of each perturbed mesh is tested by checking that every vertex lies on the convex hull.

Second method

None for this row.

What is not covered
  • One kind of smooth error; layer steps and surface roughness are not modelled.
  • A floating-point scan on a coarse grid, not an enclosure.
  • Shape 2 was run at the edge of its convex range only, the weakest choice.
  • No physical object was printed or measured.
Evidence
thread2_empirical_tolerance/mesh_tolerance_trials.py
thread2_empirical_tolerance/run_p1.log
thread2_empirical_tolerance/run_s2.log
scoping/SOFTWARE-AND-TRIALS-DATASHEET-2026-11-08.md
G5Floating-point trialEXPLORATORYSoftware, not yet released

A nearest-neighbour scan miscounts a flat body

A nearest-neighbour scan of the Phase-1 landscape reports several minima and maxima that vanish when the neighbourhood is widened, while the body has one of each.

Numbers
Neighbours within 1 grid step9 minima, 7 maxima
Within 2 steps7 and 5
Within 3 steps3 and 3
Within 6 and 10 steps1 and 1
Method

The surface is sampled on a 91 by 180 grid and grid points that are the strict minimum or maximum of the distance from the centroid among grid points within r steps are counted.

Second method

None for this row.

What is not covered
  • A larger neighbourhood does not make a scan right in general: an extra position closer than the neighbourhood would be missed.
  • One body and one grid.
  • The enclosure counts in rows E2 and G1 are the reference, not this scan.
Evidence
software/eqcert/notebooks/when_plots_lie.ipynb
software/eqcert/notebooks/wpl_helpers.py
scoping/SOFTWARE-AND-TRIALS-DATASHEET-2026-11-08.md