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

We construct the first example of a 5-dimensional simply connected compactmanifold that admits a K-contact structure but does not admit a semi-regularSasakian structure. For this, we need two ingredients: (a) to construct asuitable simply connected symplectic 4-manifold with disjoint symplecticsurfaces spanning the homology, all of them but one of genus 1 and the other ofgenus g>1, (b) to prove a bound on the second Betti number $b_2$ of analgebraic surface with $b_1=0$ and having disjoint complex curves spanning thehomology when all of them but one are of genus 1 and the other of genus g>1.

A K-contact simply connected 5-manifold with no semi-regular Sasakian structure