QEF
English
Etymology
Latin quod erat faciendum (“what was to have been done”), from Ancient Greek ὅπερ ἔδει ποιῆσαι (hoper edei poiēsai).
Initialism
QEF
- “quod erat faciendum”, “what was to have been done” – used to end a mathematical passage other than a proof.
Usage notes
Much less used than QED. Traditionally used to end passages other than proofs, such as geometric constructions – a “how-to”, not a persuasive argument.