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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We construct a class of relations on computable structures whose degree spectra form natural classes of degrees. Given any computable ordinal α and reducibility r stronger than or equal to m-reducibility, we show how to construct a structure with an intrinsically Σα invariant relation whose degree spectrum consists of all nontrivial Σα r-degrees. We extend this construction to show that Σα can be replaced by either Πα or ∆α.

Realizing Levels of the Hyperarithmetic Hierarchy as Degree Spectra of Relations on Computable Structures