A Fan Algorithm for Chow-Witt Rings of Smooth Projective Toric Varieties
Abstract
Let R be a real closed field and let XΣ be a smooth projective split toric variety. For an explicitly chosen basis rigidification r of its Picard grading, we prove that the pair (Σ,r) determines the resulting total Chow--Witt ring and give a terminating finite algorithm for all groups, products, twists, and forgetful maps. The ring is identified with an explicit fibre product of the Picard-graded diagonal I-cohomology ring and the integral inverse images of twisted Bockstein kernels over the mod-$2$ Chow ring. Using real cycle classes, we identify the first factor with the cohomology of the real toric variety with all sign local systems. We construct the mod-$2$ cycle map on invariant divisors as explicit deck-transition cocycles and obtain finite signed boundary and product matrices directly from the fan.
Related
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BibTeX
@misc{liu2026algorithm,
title = {{A Fan Algorithm for Chow-Witt Rings of Smooth Projective Toric Varieties}},
author = {Haoyang Liu and Tianle Liu and Guorui Xu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26082},
eprint = {2609.26082},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26082},
}
RIS
TY - UNPB
TI - A Fan Algorithm for Chow-Witt Rings of Smooth Projective Toric Varieties
AU - Haoyang Liu
AU - Tianle Liu
AU - Guorui Xu
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.26082
UR - https://arxiv.org/abs/2609.26082
AB - Let R be a real closed field and let X_Σ be a smooth projective split toric variety. For an explicitly chosen basis rigidification r of its Picard grading, we prove that the pair (Σ,r) determines the resulting total Chow--Witt ring and give a terminating finite algorithm for all groups, products, twists, and forgetful maps. The ring is identified with an explicit fibre product of the Picard-graded diagonal I-cohomology ring and the integral inverse images of twisted Bockstein kernels over the mod-$2$ Chow ring. Using real cycle classes, we identify the first factor with the cohomology of the real toric variety with all sign local systems. We construct the mod-$2$ cycle map on invariant divisors as explicit deck-transition cocycles and obtain finite signed boundary and product matrices directly from the fan.
ER -