Definition:QEF
Definition
The initials of quod erat faciendum, which is Latin for which was to be done.
These initials were traditionally added to the end of a geometric construction.
This is practically never seen nowadays outside translations of Euclid's The Elements.
If there is a need for such an indication, the Halmos symbol $\blacksquare$ would be used instead.
$\mathsf{Pr} \infty \mathsf{fWiki}$ does not bother to distinguish between use of QEF and the better-known QED, and recommends the use of the {{qed}} template exclusively instead.
Also known as
Some sources render QEF as Q.E.F. (that is, with dots).
Technical Note
In order to render $\blacksquare$, use the template {{qed}}.
In order to render $\Box$, use the template {{qed|lemma}}.
When {{qed}} is used, it automatically adds the page on which it is implemented to Category:Proven Results.
Sources
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): QEF
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): quod erat faciendum
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): QEF
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): QEF
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): QEF
- 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): QEF