A perfect ruler of length
ℓ
is a ruler with integer markings
= ℓ
, for which there exists an integer
such that any positive integer
is uniquely expressed as the difference
An optimal perfect ruler is one of the smallest length for fixed values of
A 4-perfect ruler of length
To verify this, we need to show that every positive integer
is uniquely expressed as the difference of two markings: This article incorporates material from perfect ruler on PlanetMath, which is licensed under the Creative Commons Attribution/Share-Alike License.
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