Ackermann coding
Encyclopedia
Ackermann coding is the encoding of finite sets as natural numbers as devised by Wilhelm Ackermann
in his 1940 paper "Die Widerspruchsfreiheit der allgemeinen Mengenlehren".
Given the natural numbers
encoding the finite sets 
, the set 
may be coded as 
Wilhelm Ackermann
Wilhelm Friedrich Ackermann was a German mathematician best known for the Ackermann function, an important example in the theory of computation....
in his 1940 paper "Die Widerspruchsfreiheit der allgemeinen Mengenlehren".
Given the natural numbers
encoding the finite sets , the set may be coded as