Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The tombstone, halmos, or end of proof mark " " is used in mathematics to denote the end of a proof, in place of the traditional abbreviation "QED" for the Latin phrase "quod erat demonstrandum" (Q.E.D.).In Unicode, it is represented as character U+220E "End of Proof". Its graphic form varies. It may be a hollow or filled rectangle or square.In AMS-LaTeX, the symbol is automatically appended at the end of a proof environment begin{proof} ... end{proof}. It can also be obtained from the commands qedsymbol or qed (the latter causes the symbol to be right aligned).It is sometimes called a halmos after its eponym Paul Halmos, who first used it in mathematical context, after seeing it was being used to indicate the end of articles in magazines.

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