PreprintCC BY 4.0arXiv
On Fano indices of weighted projective spaces
Abstract
The Sylvester sequence is defined recursively by s1=2 and si=s1⋯ si−1+1. In this paper, we prove that the Fano index of an n-dimensional well-formed weighted projective space with canonical singularities is bounded above by (sn−1)(2sn−3). This gives an affirmative answer to a conjecture of Chengxi Wang for weighted projective spaces and ℚ-factorial toric Fano varieties with Picard number one. We also investigate the distribution of Fano indices among $4$-dimensional weighted projective spaces. As the distribution of Fano indices of weighted projective spaces coincides with that of indices of terminal Calabi--Yau varieties in dimension n≤ 3, we expect this coincidence to persist also in dimension 4, and more generally, in all dimensions.
Related
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- Examples of descendent generating series for Pandharipande--Thomas stable pairs on smooth projective Fano threefolds via one-dimensional wall-crossing
- K-stability and birational rigidity of Fano 3-fold weighted complete intersections
BibTeX
@misc{liu2026fano,
title = {{On Fano indices of weighted projective spaces}},
author = {Haidong Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.03434},
eprint = {2608.03434},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.03434},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - On Fano indices of weighted projective spaces
AU - Haidong Liu
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2608.03434
UR - https://arxiv.org/abs/2608.03434
AB - The Sylvester sequence is defined recursively by s_1=2 and s_i=s_1⋯ s_i−1+1. In this paper, we prove that the Fano index of an n-dimensional well-formed weighted projective space with canonical singularities is bounded above by (s_n−1)(2s_n−3). This gives an affirmative answer to a conjecture of Chengxi Wang for weighted projective spaces and ℚ-factorial toric Fano varieties with Picard number one. We also investigate the distribution of Fano indices among $4$-dimensional weighted projective spaces. As the distribution of Fano indices of weighted projective spaces coincides with that of indices of terminal Calabi--Yau varieties in dimension n≤ 3, we expect this coincidence to persist also in dimension 4, and more generally, in all dimensions.
ER -