PreprintCC BY-NC-ND 4.0arXiv
Lifting braids over ℝℙ2 and non-orientable Lefschetz fibrations
Abstract
We show that, given a closed connected non-orientable surface F and a simple branched cover p : F → ℝℙ2 of degree d ≥ 5, every self-diffeomorphism of F is isotopic to the lift of a self-diffeomorphism of ℝℙ2 with respect to p. As an application, we show that every Lefschetz fibration over a connected surface B with ∂ B≠ ∅ and closed non-orientable regular fiber can be expressed as the composition of a simple cover of B× ℝℙ2 branched over a surface braided over B and projection onto the B-factor.
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BibTeX
@misc{bais2026lifting,
title = {{Lifting braids over $\mathbbRP^2$ and non-orientable Lefschetz fibrations}},
author = {Valentina Bais and Porter Morgan and Daniele Zuddas},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10757},
eprint = {2610.10757},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10757},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Lifting braids over ℝℙ^2 and non-orientable Lefschetz fibrations
AU - Valentina Bais
AU - Porter Morgan
AU - Daniele Zuddas
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10757
UR - https://arxiv.org/abs/2610.10757
AB - We show that, given a closed connected non-orientable surface F and a simple branched cover p : F → ℝℙ^2 of degree d ≥ 5, every self-diffeomorphism of F is isotopic to the lift of a self-diffeomorphism of ℝℙ^2 with respect to p. As an application, we show that every Lefschetz fibration over a connected surface B with ∂ B≠ ∅ and closed non-orientable regular fiber can be expressed as the composition of a simple cover of B× ℝℙ^2 branched over a surface braided over B and projection onto the B-factor.
ER -