Demonstrative pronouns (German) - genitive
The book I'm using says that the genitive forms of the word dies (dessen,derer and deren) are rarely used in modern German.
Does this mean it's only used in formal speech, or it's hardly used at all? Can anyone please explain this to me?
Its used more often in formal than in informal speech, and the genitive is in general somehow rare. So it heavily depends on your speaking partner if you will encounter it or not. I cant promise you will ever encounter it, but if you read one-two articles of the more reputable newspapers, then you have a good chance to encounter it. You might have your best shot for this when looking for verbs that come with a genitive object (like Er war dessen angeklagt.) since those can not be replaced by other grammatical constructions
EDIT: Since some others asked this. The genitive is not strange and it is good to use. Its just that some germans replace it with dative constructions and thats why it depends on your speaking partner if you encounter dessen (or any other genitiv) or von dem.
It is often used in relative sentences. (Relativsätze)
- Der Mann ist heute nicht hier ===> Genitiv: Der Mann,
dessen Frau im Spital ist, ist heute nicht hier.
- Die Frau ist heute zu Besuch ===> Genitiv: Die Frau,
deren Schwester ein Baby bekommen hat, ist heute zu Besuch.
- Das Kind,
dessen Vater... etc, and so on.
Theses genetiv relative pronouns would likely be substituted in colloquial German with constructions of preposition "von" + dative relative pronoun. (von is governed by dative)
Der Mann, dessen Frau im Krankenhaus ist, ist heute nicht hier. (dessen, genetive relative pronoun)
The man, whose wife is in the hospital, is not here today. (formal speech. This would be used in writing, in prepared speeches, on television and in formal settings or by anyone who cares for a correct usage.)
Der Mann, von dem die Frau im Krankenhaus ist, ist heute nicht hier. (von dem replaces dessen)
The man, of who(m) the wife is in the hospital, isn't here today. (colloquial speech only. This would be frowned upon in any formal context.)
Die Frau, deren Schwester ein Baby bekommen hat, ist heute zu Besuch. (deren, genetive relative pronoun)
The woman, whose sister has got a Baby, is visiting today.
Die Frau, von der die Schwester ein Baby bekommen hat, is visiting today. (colloquial only)
Das Kind, dessen Vater... (dessen, genetive neuter relative pronoun)
The child, whose father...
Das Kind, von dem der Vater... (colloquial only)
If they are used then rather in formal speech or literature. But I think it is true that for reasons of shortening and cutting corners you wouldn't use them in everyday's language. Instead of "Das Haus, dessen Fenster grau sind, gehört meinem Vater." you would rather say: "Das Haus mit den grauen Fenstern gehört meinem Vater." So in a way they are replaced by Dativformen (and please don't ask me the english word for Dativformen. I'm too tired).