(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⌋) > log_{2} 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

Go to the Dictionary of Algorithms and Data Structures home page.

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Entry modified 17 December 2004.

HTML page formatted Wed Mar 13 12:42:46 2019.

Cite this as:

Paul E. Black, "inverse Ackermann function", in
*Dictionary of Algorithms and Data Structures* [online], Paul E. Black, ed. 17 December 2004. (accessed TODAY)
Available from: https://www.nist.gov/dads/HTML/inverseAckermann.html