Tombstone (typography)
In mathematics, the tombstone, halmos, end-of-proof, or Q.E.D. symbol "∎" (or "□") is a symbol used to denote the end of a proof, in place of the traditional abbreviation "Q.E.D." for the Latin phrase ""quod erat demonstrandum"". In magazines, it is one of the various symbols used to indicate the end of an article. In Unicode, it is represented as character . Its graphic form varies, as 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 codice_1 ... codice_2. It can also  be obtained from the commands codice_3, codice_4 or codice_5 (the latter causes the symbol to be right aligned). It is sometimes called a "Halmos finality symbol" or "halmos" after the mathematician Paul Halmos, who first used it in a mathematical context in 1950. He got the idea of using it from seeing it was being used to indicate the end of articles in magazines. In his memoir "I Want to Be a Mathematician", he wrote the following: