# QED

The term “QED” is actually an abbreviation and stands for the Latin quod erat demonstrandum, meaning “which was to be demonstrated.”

QED typically is used to signify the end of a mathematical proof. The symbol

 $\square$

is often used in place of “QED,” and is called the “tombstone”, “Halmos symbol” or “Halmos tombstone” after mathematician Paul Halmos (it can vary in width, however, and sometimes it is fully or partially shaded). Halmos borrowed this symbol from magazines, where it was used to denote “end of article”.

 Title QED Canonical name QED Date of creation 2013-03-22 12:40:14 Last modified on 2013-03-22 12:40:14 Owner mathwizard (128) Last modified by mathwizard (128) Numerical id 8 Author mathwizard (128) Entry type Definition Classification msc 00A99 Synonym Q.E.D Related topic QEDInTheoreticalAndMathematicalPhysics Related topic QCDOrQuantumChromodynamics Related topic MathematicalFoundationsOfQuantumFieldTheories Related topic QuantumOperatorAlgebrasInQuantumFieldTheories Related topic GrassmanHopfAlgebrasAndTheirDualCoAlgebras Related topic FoundationsOfQuantumFieldTheories Related topic QuantumChromod Defines Halmos symbol Defines tombstone Defines Halmos tombstone