I'm familiar with the phrase quod erat demonstrandum
, usually abbreviated as Q.E.D.
But I've just come across the phrase quod esset demonstrandum
, in a LEO post - see # 10 at related discussion: Wir mussten Ihre (Kredit-)Karte einziehen.
The esset form is new to me. Interestingly, when I Google the phrase quod esset demonstrandum
, I see that most of the results are German.
The English Wikipedia article for Q.E.D. does not mention the esset form, and a search for the esset form returns no results. The German Wikipedia has no article for Q.E.D., but redirects to the article for quod erat demonstrandum
. That article does mention the esset form.
I wonder if there's a difference between German and English in the respective usage of the esset/erat variations.