From Simple English Wikipedia, the free encyclopedia
A hyperoperation is a generalization of addition, multiplication, exponentiation, tetration, etc. They are often written using Knuth's up-arrow notation. Natural number level hyperoperations can be defined recursively as a piecewise function:
![{\displaystyle H_{n}(a,b)={\begin{cases}b+1&{\text{if }}n=0\\a&{\text{if }}n=1,b=0\\0&{\text{if }}n=2,b=0\\1&{\text{if }}n\geq 3,b=0\\H_{n-1}(a,H_{n}(a,b-1))&{\text{otherwise}}\end{cases}}\,\!}](https://wikimedia.org/api/rest_v1/media/math/render/svg/7ae91667b25d20a9e3cfaa331d017d198c90d359)