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math.GT2026

Orthogonal 2-sphere basis of stable 4-sphere

Akio Kawauchi

Every stable 4-sphere is identified with the double branched covering space of a trivial surface-knot space. As a result of Wall, it is known that any two orthogonal bases of every…

math.GT2025

Fusion of boundary surface-link and ribbonness

Akio Kawauchi

A boundary surface-link of at least two components in the 4-sphere is proved to be a ribbon surface-link if the surface-link obtained from it by surgery along a local S-nontrivial…

math.GT2025

Quasi-ribbon but non-ribbon surface-link of trivial components

Akio Kawauchi

An operation on a surface-link preserving the surface-knot components called a quasi-equivalence is introduced, which induces an equivalence relation on the surface-links. A quasi-…

math.GT2024

Free ribbon lemma for surface-link

Akio Kawauchi

A free surface-link is a surface-link whose fundamental group is a free group not necessarily meridian-based. Free ribbon lemma says that every free sphere-link in the 4-sphere is…

math.GT2024

Note on surface-link of trivial components

Akio Kawauchi

As a previous result, it has shown that every sphere-link consisting of trivial components is a ribbon sphere-link. In this note, it is shown that for every closed oriented disconn…

math.GT2024

Classifying the surface-knot modules

Akio Kawauchi

The th module of a surface-knot of a genus in the 4-sphere is the th integral homology module of the infinite cyclic covering of the surface-knot complement. The reduced…