Liouville number
Noun
Meaning
Liouville number (plural Liouville numbers)
(number theory) An irrational number x with the property that, for every positive integer n, there exist integers p and q with q > 1 and such that
0
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q
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{\displaystyle \textstyle 0<\left|x-{\frac {p}{q}}\right|<{\frac {1}{q^{n}}}.}
Related terms
Examples
A Liouville number is irrational but does not have this property, so it can't be algebraic and must be transcendental.
It was the first number to be proved transcendental without having been specifically constructed for this purpose (compare with Liouville number ); the proof was given by Charles Hermite in 1873.
Kurt Mahler showed in 1953 that π is also not a Liouville number.
Mahler's classification Kurt Mahler in 1932 partitioned the transcendental numbers into 3 classes, called S, T, and U. Bugeaud (2012) p.250 Definition of these classes draws on an extension of the idea of a Liouville number (cited above).
Proof of assertion: As a consequence of this lemma, let x be a Liouville number; as noted in the article text, x is then irrational.
Since every rational number can be represented as such c/d, we will have proven that no Liouville number can be rational.