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aleph





aleph
The first letter of the Hebrew alphabet. It was first used in mathematics by Georg Cantor to denote the various orders, or sizes, of infinity: aleph-null, aleph-one, etc. An earlier (and still used) symbol for infinity, looking like an "8" on its side, was introduced in 1655 by John Wallis in his Arithmetica infinitorum but didn't appear in print until the Ars conjectandi by Jakob Bernoulli, published posthumously in 1713 by his nephew Nikolaus Bernoulli.


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   • SYMBOLS AND NOTATION