Daniel Hartman

activity

20242026

collaborators

5 papers

math.GT2026

Pseudo-Isotopy and Diffeomorphisms of the 4-Sphere I: Loops of Spheres

David Gabai, David T. Gay, Daniel Hartman

We introduce new methods in pseudo-isotopy and embedding space theory. As an application we introduce an invariant that detects nontrivial loops of embedded 2-spheres in $S^{2} \ti…

math.GT2026

Pseudo-isotopies of simply connected 4-manifolds

David Gabai, David T. Gay, Daniel Hartman +2

Perron and Quinn gave independent proofs in 1986 that every topological pseudo-isotopy of a simply-connected, compact topological 4-manifold is isotopic to the identity. Another re…

math.GT2025

On the detection of knotted spheres by their traces in high dimensions

Valentina Bais, Alessio Di Prisa, Daniel Hartman +8

For every $n \geq 4$ , we demonstrate the existence of non-isotopic smooth $(n - 2)$ -knots in $S^{n}$ with diffeomorphic traces by generalising the RBG link construction to all dimensio…

math.GT2024

Grasper families of spheres in $S^{2} \times D^{2}$ and barbell diffeomorphisms of $S^{1} \times S^{2} \times I$

Eduardo FernÃ¡ndez, David T. Gay, Daniel Hartman +1

We show that the fundamental group of framed circles in $S^{1} \times D^{3}$ injects into the fundamental group of framed spheres in $S^{2} \times D^{2}$ , so that the cokernel is the fundam…