Polynomial norms measure the size of a polynomial. For a polynomial
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(1)
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several classes of norms are commonly defined. The -norm is defined as
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(2)
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for , giving the special cases
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(3)
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(4)
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(5)
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Here,
is called the polynomial height. Note that some
authors (especially in the area of Diophantine analysis) use
as a shorthand for
and
as a shorthand for
, while others (especially
in the area of computational complexity)
use
to denote the
-norm
(Zippel 1993, p. 174).
Another class of norms is the -norms, defined by
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(6)
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for , giving the special cases
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(7)
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(8)
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(9)
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(Borwein and Erdélyi 1995, p. 6).
The integral formula extends to a quasi-norm for , and its limiting value as
is the Mahler measure.
The Baernstein quasi-norm
monotonicity conjecture concerns these norms for polynomials
whose roots lie on the unit circle
(Zhang 2026).