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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Motivated by a conjecture of Xiao, we study families of coverings of ellipticcurves and their corresponding Prym map $\Phi$. More precisely, we describe thecodifferential of the period map $P$ associated to $\Phi$ in terms of theresidue of meromorphic $1$-forms and then we use it to give a characterizationfor the coverings for which the dimension of $\ker(dP)$ is the least possibile.This is useful in order to exclude the existence of non isotrivial fibrationswith maximal relative irregularity and thus also in order to givecounterexamples to the Xiao's conjecture mentioned above. The firstcounterexample to the original conjecture, due to Pirola, is then analysed inour framework.

Covering of elliptic curves and the kernel of the Prym map