Fractional Triangle Decompositions at Partite Minimum Degree 4n/5
Abstract
We prove that every triangle-divisible balanced tripartite graph whose vertex classes have size n and whose partite minimum degree is at least 4n/5 admits a fractional triangle decomposition. Combined with the multipartite decomposition theorem of Barber, Kühn, Lo, Osthus, and Taylor, this implies that, for every fixed ε<1/5 and all sufficiently large n, every ε-dense partial Latin square of order n is completable, improving the previous asymptotic bound of 2/25. The fractional decomposition theorem is finite and exact. Its proof uses a minimum-weight perfect matching to normalize an arbitrary Farkas dual weighting, followed by an explicit direct-and-two-step routing scheme whose aggregate congestion on every off-matching edge is at most one.
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BibTeX
@misc{he2026fractional,
title = {{Fractional Triangle Decompositions at Partite Minimum Degree $4n/5$}},
author = {Hengzhi He and Guang Cheng},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.31758},
eprint = {2609.31758},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.31758},
}
RIS
TY - UNPB
TI - Fractional Triangle Decompositions at Partite Minimum Degree 4n/5
AU - Hengzhi He
AU - Guang Cheng
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.31758
UR - https://arxiv.org/abs/2609.31758
AB - We prove that every triangle-divisible balanced tripartite graph whose vertex classes have size n and whose partite minimum degree is at least 4n/5 admits a fractional triangle decomposition. Combined with the multipartite decomposition theorem of Barber, Kühn, Lo, Osthus, and Taylor, this implies that, for every fixed ε<1/5 and all sufficiently large n, every ε-dense partial Latin square of order n is completable, improving the previous asymptotic bound of 2/25. The fractional decomposition theorem is finite and exact. Its proof uses a minimum-weight perfect matching to normalize an arbitrary Farkas dual weighting, followed by an explicit direct-and-two-step routing scheme whose aggregate congestion on every off-matching edge is at most one.
ER -