After verbs of saying, thinking or showing, an 'että' clause can be compressed into a participle: add -van/-vän for something happening at the same time, or -neen for something earlier. The subordinate subject goes into the genitive - or, if it is the same as the main subject, it becomes a possessive suffix instead.
Examples
- Hän myönsi olevansa väärässä.
- He admitted that he was wrong.
- Tutkimus osoittaa väitteen perustuvan tosiasioihin.
- The study shows that the claim is based on facts.
- Väitän hänen erehtyneen jo lähtökohdissaan.
- I claim that he was mistaken already in his premises.
- Kirjoittaja korostaa näkökulmansa olevan puolueeton.
- The writer stresses that his viewpoint is impartial.
The mistake to avoid
Using a genitive pronoun when the subject is shared - say 'myönsi olevansa väärässä', not 'myönsi hänen olevan väärässä' (which would mean someone else was wrong).
Where this fits in
Looginen argumentointi, Finnish C1: Build a logical argument: claims, evidence, counterargument, persuasion.