FA-88356 / Mesh topology invariants / Open access
Boundary loops include edges shared by three faces · case 01
Non-manifold fins are counted as boundary loops.
ROOT CAUSE
An edge is treated as boundary whenever its use count is not exactly 2.
VERIFIED REPAIR
Only edges used by exactly one face are boundary.
Unsuccessful approach: Using odd incidence still treats three-face edges as boundary.
Case contract
Input: list of polygon faces (vertex index lists). V counts referenced vertices, E distinct undirected edges (closing edge included), F faces, chi=V-E+F, C connected components (via edges), B boundary loops = components of the graph of edges used by exactly one face. Return [V,E,F,chi,C,B,genus] with genus=(2C-chi-B)/2 or null when that numerator is odd (non-orientable signal).
Why this case matters
Mesh processing pipelines (remeshing, export, simulation, printing) trust these topological counts and adjacency answers; a wrong invariant silently accepts broken meshes or rejects valid ones.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
faces=x
edges={}
for f in faces:
n=len(f)
for i in range(n):
a,b=f[i],f[(i+1)%n]
k=(min(a,b),max(a,b))
edges[k]=edges.get(k,0)+1
verts=sorted({v for f in faces for v in f})
V=len(verts)
E=len(edges)
Fc=len(faces)
chi=V-E+Fc
parent={v:v for v in verts}
def find(v):
while parent[v]!=v:
v=parent[v]
return v
for a,b in edges:
ra,rb=find(a),find(b)
if ra!=rb: parent[ra]=rb
comps=len({find(v) for v in verts})
bpar={}
def bfind(v):
while bpar[v]!=v:
v=bpar[v]
return v
for (a,b),c in edges.items():
if c!=2:
bpar.setdefault(a,a)
bpar.setdefault(b,b)
ra,rb=bfind(a),bfind(b)
if ra!=rb: bpar[ra]=rb
loops=len({bfind(v) for v in bpar})
g=2*comps-chi-loops
genus=None if g%2 else g//2
return [V,E,Fc,chi,comps,loops,genus]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['octahedron', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 1], [5, 2, 1], [5, 3, 2], [5, 4, 3], [5, 1, 4]]], [6, 12, 8, 2, 1, 0, 0]], ['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetra plus disk', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [10, 11, 12], [10, 12, 13], [10, 13, 14], [10, 14, 15], [10, 15, 11]]], [10, 16, 9, 3, 2, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| tetrahedron | [4, 6, 4, 2, 1, 0, 0] | [4, 6, 4, 2, 1, 0, 0] | Passed |
| cube quads | [8, 12, 6, 2, 1, 0, 0] | [8, 12, 6, 2, 1, 0, 0] | Passed |
| octahedron | [6, 12, 8, 2, 1, 0, 0] | [6, 12, 8, 2, 1, 0, 0] | Passed |
| quad torus | [9, 18, 9, 0, 1, 0, 1] | [9, 18, 9, 0, 1, 0, 1] | Passed |
| triangle torus | [9, 27, 18, 0, 1, 0, 1] | [9, 27, 18, 0, 1, 0, 1] | Passed |
| disk fan | [6, 10, 5, 1, 1, 1, 0] | [6, 10, 5, 1, 1, 1, 0] | Passed |
| tetrahedra sharing a face | [5, 9, 7, 3, 1, 1, -1] | [5, 9, 7, 3, 1, 0, None] | Failed |
SHA-256 / bad96ca59f229e57758d6723595f94f0d55673c7cc948c278128f08e67743de1
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
faces=x
edges={}
for f in faces:
n=len(f)
for i in range(n):
a,b=f[i],f[(i+1)%n]
k=(min(a,b),max(a,b))
edges[k]=edges.get(k,0)+1
verts=sorted({v for f in faces for v in f})
V=len(verts)
E=len(edges)
Fc=len(faces)
chi=V-E+Fc
parent={v:v for v in verts}
def find(v):
while parent[v]!=v:
v=parent[v]
return v
for a,b in edges:
ra,rb=find(a),find(b)
if ra!=rb: parent[ra]=rb
comps=len({find(v) for v in verts})
bpar={}
def bfind(v):
while bpar[v]!=v:
v=bpar[v]
return v
for (a,b),c in edges.items():
if c%2==1:
bpar.setdefault(a,a)
bpar.setdefault(b,b)
ra,rb=bfind(a),bfind(b)
if ra!=rb: bpar[ra]=rb
loops=len({bfind(v) for v in bpar})
g=2*comps-chi-loops
genus=None if g%2 else g//2
return [V,E,Fc,chi,comps,loops,genus]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['octahedron', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 1], [5, 2, 1], [5, 3, 2], [5, 4, 3], [5, 1, 4]]], [6, 12, 8, 2, 1, 0, 0]], ['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetra plus disk', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [10, 11, 12], [10, 12, 13], [10, 13, 14], [10, 14, 15], [10, 15, 11]]], [10, 16, 9, 3, 2, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| tetrahedron | [4, 6, 4, 2, 1, 0, 0] | [4, 6, 4, 2, 1, 0, 0] | Passed |
| cube quads | [8, 12, 6, 2, 1, 0, 0] | [8, 12, 6, 2, 1, 0, 0] | Passed |
| octahedron | [6, 12, 8, 2, 1, 0, 0] | [6, 12, 8, 2, 1, 0, 0] | Passed |
| quad torus | [9, 18, 9, 0, 1, 0, 1] | [9, 18, 9, 0, 1, 0, 1] | Passed |
| triangle torus | [9, 27, 18, 0, 1, 0, 1] | [9, 27, 18, 0, 1, 0, 1] | Passed |
| disk fan | [6, 10, 5, 1, 1, 1, 0] | [6, 10, 5, 1, 1, 1, 0] | Passed |
| tetrahedra sharing a face | [5, 9, 7, 3, 1, 1, -1] | [5, 9, 7, 3, 1, 0, None] | Failed |
SHA-256 / d37f2edc9d95f33155ff8f6d1115cf83729c89e5a11fb5c1d2539e8b8edf1e02
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
faces=x
edges={}
for f in faces:
n=len(f)
for i in range(n):
a,b=f[i],f[(i+1)%n]
k=(min(a,b),max(a,b))
edges[k]=edges.get(k,0)+1
verts=sorted({v for f in faces for v in f})
V=len(verts)
E=len(edges)
Fc=len(faces)
chi=V-E+Fc
parent={v:v for v in verts}
def find(v):
while parent[v]!=v:
v=parent[v]
return v
for a,b in edges:
ra,rb=find(a),find(b)
if ra!=rb: parent[ra]=rb
comps=len({find(v) for v in verts})
bpar={}
def bfind(v):
while bpar[v]!=v:
v=bpar[v]
return v
for (a,b),c in edges.items():
if c==1:
bpar.setdefault(a,a)
bpar.setdefault(b,b)
ra,rb=bfind(a),bfind(b)
if ra!=rb: bpar[ra]=rb
loops=len({bfind(v) for v in bpar})
g=2*comps-chi-loops
genus=None if g%2 else g//2
return [V,E,Fc,chi,comps,loops,genus]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['octahedron', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 1], [5, 2, 1], [5, 3, 2], [5, 4, 3], [5, 1, 4]]], [6, 12, 8, 2, 1, 0, 0]], ['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad torus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0], [3, 6, 7, 4], [4, 7, 8, 5], [5, 8, 6, 3], [6, 0, 1, 7], [7, 1, 2, 8], [8, 2, 0, 6]]], [9, 18, 9, 0, 1, 0, 1]], ['triangle torus', [[[0, 3, 4], [0, 4, 1], [1, 4, 5], [1, 5, 2], [2, 5, 3], [2, 3, 0], [3, 6, 7], [3, 7, 4], [4, 7, 8], [4, 8, 5], [5, 8, 6], [5, 6, 3], [6, 0, 1], [6, 1, 7], [7, 1, 2], [7, 2, 8], [8, 2, 0], [8, 0, 6]]], [9, 27, 18, 0, 1, 0, 1]], ['disk fan', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1]]], [6, 10, 5, 1, 1, 1, 0]], ['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['quad annulus', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 3, 0]]], [6, 9, 3, 0, 1, 2, 0]], ['mobius strip', [[[0, 3, 4, 1], [1, 4, 5, 2], [2, 5, 0, 3]]], [6, 9, 3, 0, 1, 1, None]], ['projective plane', [[[0, 1, 2], [0, 2, 3], [0, 3, 4], [0, 4, 5], [0, 5, 1], [1, 2, 4], [2, 3, 5], [3, 4, 1], [4, 5, 2], [5, 1, 3]]], [6, 15, 10, 1, 1, 0, None]], ['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['two tetrahedra', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [4, 6, 5], [4, 5, 7], [5, 6, 7], [4, 7, 6]]], [8, 12, 8, 4, 2, 0, 0]], ['gapped indices', [[[0, 1, 5], [1, 7, 5]]], [4, 5, 2, 1, 1, 1, 0]], ['open cylinder', [[[0, 1, 5], [0, 5, 4], [1, 2, 6], [1, 6, 5], [2, 3, 7], [2, 7, 6], [3, 0, 4], [3, 4, 7]]], [8, 16, 8, 0, 1, 2, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]], [['tetrahedron', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2]]], [4, 6, 4, 2, 1, 0, 0]], ['cube quads', [[[0, 3, 2, 1], [4, 5, 6, 7], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6], [3, 0, 4, 7]]], [8, 12, 6, 2, 1, 0, 0]], ['book of three pages', [[[0, 1, 2], [1, 0, 3], [0, 1, 4]]], [5, 7, 3, 1, 1, 1, 0]], ['quad grid', [[[0, 1, 4, 3], [1, 2, 5, 4], [3, 4, 7, 6], [4, 5, 8, 7]]], [9, 12, 4, 1, 1, 1, 0]], ['mixed quad and triangle', [[[0, 1, 2, 3], [3, 2, 4]]], [5, 6, 2, 1, 1, 1, 0]], ['tetra plus disk', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [10, 11, 12], [10, 12, 13], [10, 13, 14], [10, 14, 15], [10, 15, 11]]], [10, 16, 9, 3, 2, 1, 0]], ['tetrahedra sharing a face', [[[0, 2, 1], [0, 1, 3], [1, 2, 3], [0, 3, 2], [0, 1, 4], [1, 2, 4], [0, 4, 2]]], [5, 9, 7, 3, 1, 0, None]]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| tetrahedron | [4, 6, 4, 2, 1, 0, 0] | [4, 6, 4, 2, 1, 0, 0] | Passed |
| cube quads | [8, 12, 6, 2, 1, 0, 0] | [8, 12, 6, 2, 1, 0, 0] | Passed |
| octahedron | [6, 12, 8, 2, 1, 0, 0] | [6, 12, 8, 2, 1, 0, 0] | Passed |
| quad torus | [9, 18, 9, 0, 1, 0, 1] | [9, 18, 9, 0, 1, 0, 1] | Passed |
| triangle torus | [9, 27, 18, 0, 1, 0, 1] | [9, 27, 18, 0, 1, 0, 1] | Passed |
| disk fan | [6, 10, 5, 1, 1, 1, 0] | [6, 10, 5, 1, 1, 1, 0] | Passed |
| tetrahedra sharing a face | [5, 9, 7, 3, 1, 0, None] | [5, 9, 7, 3, 1, 0, None] | Passed |
SHA-256 / 0385236f776c486b8d6d570b4399c05915cef67b698844cdfa30eb010bc452bb
Verification & scope
Pure combinatorial teaching model over integer face lists with a stipulated contract; no geometry kernel or file format is implied. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:51:07.472355+00:00.
Case digest / 100ef65b3e9a44072a1e76dab9c07f1451be061a2a9314d266bc83753f93b9c2