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A filled or hollow square ending a proof.
Also known as: Halmos symbol, End of proof mark, Tombstone, QED symbol
A small square at the end of a proof marks where it finishes, replacing the older abbreviation QED. It was introduced by Paul Halmos, who took it from magazine typography, and the filled and hollow forms are used interchangeably.
Marks the end of a proof, taking the place of the abbreviation for 'quod erat demonstrandum'.
Contexts: Mathematics
Was introduced into mathematical writing by Paul Halmos, who borrowed it from the end-of-article marks used in magazines.
Contexts: Mathematics
A small square, either solid or hollow, set at the end of the last line of an argument and usually pushed to the right margin.