David Hilbert
Curve

In 1890, Giuseppe Peano had published an article in the Mathematische Annalen describing the historically first space-filling curve. In response, Hilbert designed his own construction of such a curve, which is now called Hilbert curve. Approximations to this curve are constructed iteratively according to the replacement rules in the first picture of this section. The curve itself is then the pointwise limit.
combination:two_responses, keywords:letter_frequency