A symbol that ends a proof, usually mathematical. QED and w^5 are the most common EOP symbols. Many people make up their own; mine is an Interstate 99 shield with a circle with a line thru it around it, representing my dislike of Interstate 99. On E2 I must approximate it (9/9). Others I have seen are a triangular gastropod and 1=2; the latter is not recommended on a test though.

Another, more standard, symbol to end a proof would be the contradiction symbol. Used in proofs of method reductio ad absurdum ('proof by contradiction'), the Contradiction symbol indicates that an obvious contradiction has been reached and so (generally) the proof is ended. The symbol resembles the Scottish flag with four bullet-holes through it, and is not available in standard LaTeX fonts.

(Brackets added for clarity)
The symbol can be described as ((two parallel lines) intersected by (two parallel lines)) with ((four filled circles) at the (centrepoint of the square which the approximate endpoints of the four lines will form)).

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