Dedekind

Throughout the 20th century, new Dedekind numbers popped up intermittently, usually with decades of waiting in between.

That special requirement makes the Dedekind numbers difficult to compute.

To satisfy the Dedekind conditions and count toward the tally of functions, true-false functions must follow certain rules.

Its corners are all colored either white or red, and the nth Dedekind number counts the number of colorings where no white point is topped by a red point.

Mathematicians have been waiting 32 years to find out the value of the ninth Dedekind number, part of a series of numbers that was first discovered in the 19th century.