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

In the space Ir of invariant r-dimensional subspaces of a null system in (2r + l)-dimensional projective space, W.L. Chow characterized the basic group of transformations as all the bijections : I, -+ Ir, for which both W and -1 preserve adjacency. In the present paper we show that the two conditions p: I, -+ I, is a surjection and W preserves adjacency are sufficient to characterize the basic group. At the end of this paper we give an application to Lie geometry.

Adjacency preserving mappings of invariant subspaces of a null system