10
votes
3answers
173 views

Konjunktiv in mathematics without subject at the beginning

A follow-up question to the use of "sei" in mathematics. Compare the two following sentences, which are both common: Es sei f eine stetige Funktion. Sei f eine stetige Funktion. Would ...
21
votes
5answers
716 views

Why use Konjunktiv I in mathematics?

Konjunktiv I is mostly used for indirect speech and wishes. The following sentence is neither: Die Funktionen ψn(x) seien Eigenfunktionen eines Hamiltonoperators Ĥ. Why is the Konjunktiv I used ...