We consider percolation problems on regular trees and some pre-fractal graphs.
Central limit theorems for the number of open clusters in a finite box are obtained. For regular trees and some classes of Sierpiński carpet lattices, we can prove the central limit theorems for all p ∈ (0, 1). §1. Introduction and ResultsCentral limit theorems (CLT's) for percolation problems have been studied by many authors (see Grimmett [5]. Using this method together with the ergodic theorem, Penrose [6] proved a general CLT which can be applied to several models. In this note, by using the argument in [9] we study a CLT for percolation problems on regular trees and Sierpiński carpet lattices, where the ergodic theorem is not available.