Noninjective harmonic maps between closed negatively curved manifolds in every dimension at least three

For every dimension n ≥ 3, this paper constructs two smooth metrics on a closed, connected, orientable n-manifold, both with sectional curvature at most −1. The harmonic representative of the identity homotopy class has negative Jacobian at some point and is therefore not injective. This provides a counterexample to Problem 111 in every dimension n ≥ 3. Repository: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometryPDF at the deposited version: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometry/blob/b4f17a71d1712073bf82196a01c29ae04292e5c1/papers/problem_111_harmonic_maps.pdfTeX source at the deposited version: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometry/blob/b4f17a71d1712073bf82196a01c29ae04292e5c1/papers/problem_111_harmonic_maps.tex

Authors

Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2026-11-05
DOI
https://doi.org/10.5281/zenodo.23984895
Primary Topic
Geometric Analysis and Curvature Flows
Type
preprint
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preprint

Noninjective harmonic maps between closed negatively curved manifolds in every dimension at least three

opensource120
Zenodo (CERN European Organization for Nuclear Research)
Geometric Analysis and Curvature Flows
preprint

Noninjective harmonic maps between closed negatively curved manifolds in every dimension at least three

opensource120
preprint en

Abstract

For every dimension n ≥ 3, this paper constructs two smooth metrics on a closed, connected, orientable n-manifold, both with sectional curvature at most −1. The harmonic representative of the identity homotopy class has negative Jacobian at some point and is therefore not injective. This provides a counterexample to Problem 111 in every dimension n ≥ 3. Repository: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometryPDF at the deposited version: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometry/blob/b4f17a71d1712073bf82196a01c29ae04292e5c1/papers/problem_111_harmonic_maps.pdfTeX source at the deposited version: https://github.com/opensource120/Some-Answers-to-Yau-s-120-open-problems-in-geometry/blob/b4f17a71d1712073bf82196a01c29ae04292e5c1/papers/problem_111_harmonic_maps.tex

Zenodo (CERN European Organization for Nuclear Research)
Geometric Analysis and Curvature Flows
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