Sæll Haraldr!

--- In norse_course@yahoogroups.com, "haraldr_eikinskjaldi"
<gagfran_13@...> wrote:
> hi, in lesson 4, it is write that "endings like -um that have an u
in them, will modify any a in preceding stems, changing them to ö",

Correct.

> ok, this is prety simple. But in lessons, it happens some times
that a "a" in the stems is not change to a "ö" even if the word have
a "u" endings.

This rule is universal in Old Norse. See below.

For exemples, (in exercise and solution of lesson
> 5,) : eta þeir vel í VANGINUM, brennr í GARÐINUM, víkingarnir
biða með JARLINUM.

The U in each of these examples is part of the suffixed definite
article, which is not a part of the word proper. The dative plurals
of the 3 words you cited are: vöngum, görðum, and jörlum - with the
definite article: vöngunum, görðunum, jörlunum.

Even in the reference in lesson 6 : haukum,
> haukinum, haukunum, manninum. These words shouldn't take a "ö" ???

U-umlaut does not effect a preceeding AU, as in 'haukinum'. About
the dative 'manninum', where the U is part of the article, see above.

Regards,
Konrad.