Definition:QEI
Definition
The initials of Quod Erat Inveniendum, which is Latin for which was to be found.
These initials were traditionally added after the completion of a calculation (either arithmetic or algebraic).
This is practically never seen nowadays outside translations of historical texts.
If there were ever 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 QEI and the better-known QED, and recommends the use of the {{qed}} template exclusively instead.
Also known as
Some sources render it as Q.E.I. (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
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): QEI
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): QEI