10
votes
3answers
162 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 ...
18
votes
4answers
545 views

Why use Konjunktiv I in mathematics?

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