analysis / Smooth dynamical systems; topological entropy and homology

Shub's entropy conjecture for C1 self-maps

Theorem 1.1: for some q≥1q\ge1 there is a C1C^1 self-map ff of M=(R/100Z)×(S2)q+1M=(\mathbb R/100\mathbb Z)\times(S^2)^{q+1} with htop(f)=0h_{\mathrm{top}}(f)=0 while f∗f_* on H2(M;R)H_2(M;\mathbb R) has eigenvalue 2, so htop(f)<log⁡ρ(f∗)h_{\mathrm{top}}(f)<\log\rho(f_*). The map is noninvertible, dim⁡M=2q+3≥5\dim M=2q+3\ge5, and the eigenvalue sits in intermediate degree, consistent with the known first-homology, top-degree and C∞C^\infty positive results. It does not address C1C^1 diffeomorphisms, CrC^r maps for r≥2r\ge2, or the conjecture in low dimensions.

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analysisSep 25, 2026Significance 48/100Registry: lean checked

Shub's entropy conjecture for C1 self-maps

Prior state unknown→disproved

Theorem 1.1: for some q≥1q\ge1 there is a C1C^1 self-map ff of M=(R/100Z)×(S2)q+1M=(\mathbb R/100\mathbb Z)\times(S^2)^{q+1} with htop(f)=0h_{\mathrm{top}}(f)=0 while f∗f_* on H2(M;R)H_2(M;\mathbb R) has eigenvalue 2, so htop(f)<log⁡ρ(f∗)h_{\mathrm{top}}(f)<\log\rho(f_*). The map is noninvertible, dim⁡M=2q+3≥5\dim M=2q+3\ge5, and the eigenvalue sits in intermediate degree, consistent with the known first-homology, top-degree and C∞C^\infty positive results. It does no…

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Theorem 1.1: for some q≥1q\ge1 there is a C1C^1 self-map ff of M=(R/100Z)×(S2)q+1M=(\mathbb R/100\mathbb Z)\times(S^2)^{q+1} with htop(f)=0h_{\mathrm{top}}(f)=0 while f∗f_* on H2(M;R)H_2(M;\mathbb R) has eigenvalue 2, so htop(f)<log⁡ρ(f∗)h_{\mathrm{top}}(f)<\log\rho(f_*). The map is noninvertible, dim⁡M=2q+3≥5\dim M=2q+3\ge5, and the eigenvalue sits in intermediate degree, consistent with the known first-homology, top-degree and C∞C^\infty positive results. It does not address C1C^1 diffeomorphisms, CrC^r maps for r≥2r\ge2, or the conjecture in low dimensions.

Theorem 1.1: for some q≥1q\ge1 there is a C1C^1 self-map ff of M=(R/100Z)×(S2)q+1M=(\mathbb R/100\mathbb Z)\times(S^2)^{q+1} with htop(f)=0h_{\mathrm{top}}(f)=0 while f∗f_* on H2(M;R)H_2(M;\mathbb R) has eigenvalue 2, so htop(f)<log⁡ρ(f∗)h_{\mathrm{top}}(f)<\log\rho(f_*). The map is noninvertible, dim⁡M=2q+3≥5\dim M=2q+3\ge5, and the eigenvalue sits in intermediate degree, consistent with the known first-homology, top-degree and C∞C^\infty positive results. It does not address C1C^1 diffeomorphisms, CrC^r maps for r≥2r\ge2, or the conjecture in low dimensions.

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Shub's entropy conjecture for C1 self-maps — Mathematical Frontier Network