Finite modification of Bernoulli percolation

For $0<p<1$, every prescribed state pattern on a finite edge set has positive conditional probability given all exterior states: independence makes it $p^a(1-p{)}^b$ for $a$ prescribed open and $b$ prescribed closed edges. Thus a positive-probability exterior event remains possible after any finite local surgery. This is the finite-energy property of Bernoulli percolation, and applies equally to dual bond percolation.