# Knot concordances in $S^1\times S^2$ and exotic smooth $4$-manifolds

## TL;DR

This paper explores the construction of exotic smooth 4-manifolds using knots in $S^1\times S^2$, demonstrating that certain exotic pairs can be Stein manifolds and providing new examples of such manifolds.

## Contribution

It constructs absolutely exotic Stein 4-manifold pairs using hyperbolic knots with trivial symmetry in $S^1\times S^2$, extending previous methods.

## Key findings

- Existence of absolutely exotic Stein manifold pairs.
- Construction preserves the Stein property.
- Generation of exotic contractible Stein manifolds.

## Abstract

It is known that there is a unique concordance class in the free homotopy class of $S^1\times pt \subset S^1 \times S^2$. The constructive proof of this fact is given by the second author. It turns out that all the concordances in this construction are invertible. The knots $K\subset S^{1}\times S^{2}$ with hyperbolic complements and trivial symmetry group are special interest here, because they can be used to generate absolutely exotic compact 4-manifolds by the recipe given by Akbulut and Ruberman. Here we built absolutely exotic manifold pairs by this construction, and show that this construction keeps the Stein property of the $4$-manifolds we start out with. By using this we establish the existence of an absolutely exotic contractible Stein manifold pair, and absolutely exotic homotopy $S^1\times B^3$ Stein manifold pair.