Catching jumps of metric-valued mappings with Lipschitz functions

This paper demonstrates that while a continuous map into a metric space is of bounded variation if and only if its composition with every Lipschitz function is of bounded variation, this characterization fails for discontinuous maps in spaces like 2\ell_2, infinite metric trees, and Laakso-type spaces, though it remains valid for ultrametric spaces without continuity assumptions.

Dmitriy Stolyarov, Alexander Tyulenev2026-03-05🔢 math

Gromov hyperbolicity I: the dimension-free Gehring-Hayman inequality for quasigeodesics

This paper establishes a dimension-free Gehring-Hayman inequality for quasigeodesics in infinite-dimensional spaces by developing a new approach that relaxes previous constraints on geodesics and quasiconformal equivalence, thereby affirmatively resolving a long-standing open problem regarding the relationship between uniformity and Gromov hyperbolicity in Banach spaces.

Chang-Yu Guo, Manzi Huang, Xiantao Wang2026-03-05🔢 math