English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Determining unknotting numbers is a large and widely studied problem. Weconsider the more general question of the unknotting number of a spatial graph.We show the unknotting number of spatial graphs is subadditive. Let $g$ be anembedding of a planar graph $G$, then we show $u(g) \geq \max\{u(s) |$ $s$ is anon-overlapping set of constituents of $g\}$.  Focusing on $\theta$-curves, we determine the exact unknotting numbers of the$\theta$-curves in the Litherland-Moriuchi Table. Additionally, we demonstrateunknotting crossing changes for all of the curves. In doing this we introducenew methods for obstructing unknotting number $1$ in $\theta$-curves.

Unknotting numbers for prime $\theta$-curves up to seven crossings