Dice Question Streamline Icon: https://streamlinehq.com

Inequality between sequential topological complexity and cohomological dimension for epimorphisms of geometrically finite groups

Determine whether, for every epimorphism φ: Γ → Λ of geometrically finite groups and integer r≥2, the inequality cdp(φ^{r−1}) ≤ TC^r(φ) ≤ cdp(φ^r) holds, where φ^k denotes the k-fold product homomorphism φ × ⋯ × φ: Γ^k → Λ^k and TC^r(φ) denotes the sequential topological complexity of the classifying map Bφ: BΓ → BΛ.

Information Square Streamline Icon: https://streamlinehq.com

Background

The authors develop the sequential topological complexity TCr of maps and relate it to LS-category bounds and cohomological dimensions. For spaces, a known inequality cdp(Γ{r−1}) ≤ TCr(Γ) ≤ cdp(Γr) motivates seeking an analogous relation for homomorphisms.

Confirming this inequality for epimorphisms of geometrically finite groups would connect TCr(φ) tightly to product cohomological dimensions of φ, refining lower and upper bounds and potentially guiding computations for broad classes of group homomorphisms.

References

Question 6.11. Is the following equality cdpφ r´1q ď TC prq ď cdpφ q true for the epimor-

phisms of geometrically finite groups? This question is motivated by the following fact cdpΓ r´1 q ď TC rΓq ď cdpΓ q.

On the sequential topological complexity of group homomorphisms (2402.13389 - Kuanyshov, 20 Feb 2024) in Question 6.11 (Section 6), page 18