inverse Ackermann function

(algorithm)

Definition: A function of two parameters whose value grows very, very slowly.

Formal Definition: α(m,n) = min{i≥ 1: A(i, m/n) > log₂ n} where A(i,j) is Ackermann's function.

Also known as α.

See also Ackermann's function.

Note: This is not strictly the inverse of Ackermann's function. Rather, this grows as slowly as Ackermann's function grows quickly.

After [CLR90, page 452].

Author: PEB

If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.

Entry modified 17 December 2004.
HTML page formatted Fri Mar 25 16:20:34 2011.

Cite this as:
Paul E. Black, "inverse Ackermann function", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed., U.S. National Institute of Standards and Technology. 17 December 2004. (accessed TODAY) Available from: http://www.nist.gov/dads/HTML/inverseAckermann.html