Uwe Brauer <oub@mat.ucm.es> writes:

> Following your advice to read the documentation more carefully, I tried
> the following setting
>
> (setq gnus-thread-sort-functions
>       '(gnus-thread-sort-by-number
>         gnus-thread-sort-by-date))
>
> (setq gnus-sort-functions
>       '(gnus-article-sort-by-number
>         gnus-article-sort-by-date))

I guess you want gnus-thread-sort-by-most-recent-date and
gnus-article-sort-by-most-recent-date because gnus-thread-sort-by-date
sorts by the date of the root article.

Bye,
Tassilo