While you’re right that there is a rabbit hole to go down, we just didn’t have a solution for this so far.
“Matthias’ car” translates as “Matthias Auto”, which could also be a new Disney character.
The problem is much less frequent in German, though, because our plurals don’t generally end with a ‘s’.
I wouldn’t know having seen an apostrophe in genitive in a formal text before, but no idea. Maybe there’s regional differences. Would explain why Duden lists both.
Ich wüsste nicht, dass ich schonmal einen Apostroph beim Genitiv in einem formalen Text gesehen hätte, aber ja, kein Plan. Vielleicht gibt’s da auch regionale Unterschiede. Würde erklären, warum der Duden beides listet…
But Duden listing Matthias as a possible genitive is wild. It seems they just list it in a weird way, because Jeremia is certainly not a reasonable genitive of Jeremia:
Hmm, I think Jeremia is an irregular case, due to it mostly being a biblical name and I think in biblical texts, they write it as “des Jeremia”. No idea, if that was just en vogue when the bible got translated or what the reason is for that.
While you’re right that there is a rabbit hole to go down, we just didn’t have a solution for this so far.
“Matthias’ car” translates as “Matthias Auto”, which could also be a new Disney character.
The problem is much less frequent in German, though, because our plurals don’t generally end with a ‘s’.
What? That’s completely untrue! Any time, the word ends on an s sound, the apostrophe moves to [the end of the word].
Matthias’s car (or alternatively, Matthias’ car) is Matthias’ Auto.
Assuming the final e is not pronounced, Alice’s car becomes Alice’ Auto. Alternatively, it can be Alices Auto if the final e is pronounced.
Interestingly, the Duden also spits out
Matthias'as possible genitive: https://www.duden.de/deklination/substantive/Matthias_VornameBut I was then unsure, if they had already integrated the Deppenapostroph-rule.
I wouldn’t know having seen an apostrophe in genitive in a formal text before, but no idea. Maybe there’s regional differences. Would explain why Duden lists both.
Original German comment:
Interessanterweise hat der Duden auch
Matthias'als möglichen Genitiv ausgespuckt: https://www.duden.de/deklination/substantive/Matthias_VornameAber ich war mir dann unsicher, ob die schon direkt die Deppenapostroph-Regel aufgenommen hatten.
Ich wüsste nicht, dass ich schonmal einen Apostroph beim Genitiv in einem formalen Text gesehen hätte, aber ja, kein Plan. Vielleicht gibt’s da auch regionale Unterschiede. Würde erklären, warum der Duden beides listet…
(Ftr: This is an English-language community.)
But Duden listing Matthias as a possible genitive is wild. It seems they just list it in a weird way, because Jeremia is certainly not a reasonable genitive of Jeremia:
Hmm, I think Jeremia is an irregular case, due to it mostly being a biblical name and I think in biblical texts, they write it as “des Jeremia”. No idea, if that was just en vogue when the bible got translated or what the reason is for that.
But the Duden describes the general rule of thumb for nouns ending in ‘s’ (or similar sounds) by extending them with “-es”: https://www.duden.de/sprachwissen/sprachratgeber/Genitiv-auf-s-oder-es
But “des Matthiases” just sounds archaic.
They also list “des Hans” as the only possible genitive: https://www.duden.de/deklination/substantive/Hans_Mann
So, maybe these are special cases, too…