The numbers count a variety of seemingly unrelated mathematical structures. The post Ninth Dedekind Number Found by Two Independent Groups first appeared on Quanta Magazine
Richard Dedekind was a 19th-century mathematical giant, responsible for reshaping the field right down to its foundations. He was the first to give a rigorous definition of infinity; he also came up with the definition of the real numbers that form the basis of much of modern mathematics. In 1897, he published an investigation into a certain numerical pattern. That work led him to define a…