Great time complexity for alpha (n)

Question

What does O (alpha (n)) mean? I recently came across 2048, but in terms of runtime, and one of the blocks had this. Thank!

Answer 1

This seems to be a link to the reverse function of Ackermann , written asα(n)

From Wikipedia:

This converse appears in the time complexity of some algorithms, such as a data structure with unrelated sets and the Chazelle algorithm for minimal spanning trees.