The simplest tree-rearrangement, known as nearest-neighbor interchange, exchanges the connectivity of four subtrees within the main tree. Because there are three possible ways of connecting four subtrees, and one is the original connectivity, each interchange creates two new trees. Exhaustively searching the possible nearest-neighbors for each possible set of subtrees is the slowest but most optimizing way of performing this search.
The simplest tree rearrangement, known as nearest-neighbor interchange, exchanges the connections of four subtrees within the main tree. Because there are three possible ways to connect four subtrees, and one is the original connection, each interchange creates two new trees. Exhaustively searching for the nearest neighbors for each possible set of subtrees is the slowest but most efficient way of performing this search.