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P1F-Census: Perfect 1-Factorizations of K18 and K20 with Non-Trivial Automorphisms

Repository (source code, run scripts, catalogues): https://github.com/LeAndr-Graph/P1F-Census

K18: there are exactly 10,710 pairwise non-isomorphic perfect 1-factorizations (P1Fs) of K18 with a non-trivial automorphism group (|Aut| > 1).

|Aut| 2 3 4 8 16 17 272
classes 10,179 351 144 22 12 1 1

Catalogue: AllResults/K18_P1F_aut_gt1.txt · dataset DOI 10.5281/zenodo.22238984 · runs: runs/K18/ · paper: submitted to Australas. J. Combin.

K20: there are exactly 149,836 pairwise non-isomorphic P1Fs of K20 with |Aut| >= 3: 230 with |Aut| > 3 and 149,606 with |Aut| = 3.

|Aut| 3 6 9 18 19 57 171 342
classes 149,606 168 46 9 3 1 2 1

Catalogues: AllResults/K20_P1F_aut_gt3.txt, AllResults/K20_P1F_aut_eq3.txt.gz · dataset DOIs 10.5281/zenodo.22215011 (|Aut| > 3), 10.5281/zenodo.22880728 (|Aut| = 3) · runs: runs/K20/

Derived: 104,088 P1Fs of K17,17 from the K18 catalogue, 10.5281/zenodo.22548329.

Verification: the same engine reproduces the known K14 classification (Dinitz and Garnick, 1996) and the K16 classes with |Aut| > 1 (Gill and Wanless, 2020): AllResults/K14_P1F_aut_gt1.txt (21), AllResults/K16_P1F_aut_gt1.txt (89), runs/K14/, runs/K16/, regression/.

Authors

Andrei V. Ivanov, ORCID 0000-0002-1574-6716, died September 2026.
Leonid M. Tertitski, ORCID 0009-0002-7556-9552 (corresponding).

Where the details are

Topic File
definitions, catalogue format, record numbering, atomic Latin squares AllResults/ReadMe.md
each computation: what it searches, expected result, runtime ReadMe.md in each runs/ folder
theorems the search relies on (Ihrig 1986) docs/theorems.md
build, configuration, regression suite docs/build.md
what is open (K20 |Aut| = 2) runs/K20/ReadMe.md

Citing

Cite the dataset DOI for the graph in question, for example:

Ivanov, A. V., & Tertitski, L. M. (2026). Perfect one-factorizations of K18 with non-trivial automorphism group: a complete catalogue (Version 1.0.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.22238984

Questions, missing or extra classes, failed reproductions: open an issue.

License

Source code: MIT (LICENSE). Catalogues in AllResults/: CC0 1.0.