Von Mises
Émile Borel was one of the first mathematicians to formally address randomness in 1909, and introduced normal numbers. In 1919 Richard von Mises gave the first definition of algorithmic randomness via the impossibility of a gambling system. He advanced the frequency theory of randomness in terms of what he called "the collective", i.e. a random sequence. Von Mises regarded the randomness of a collective as an empirical law, established by experience. He related the "disorder" or randomness of a collective to the lack of success of attempted gambling systems. This approach led him to suggest a definition of randomness that was later refined and made mathematically rigorous by Alonzo Church by using computable functions in 1940. Von Mises likened the principle of the "impossibility of a gambling system" to the principle of the conservation of energy, a law that cannot be proven, but has held true in repeated experiments.