We can use the problem's list of moves to create the children of a state u in a search tree:

• For each move in the move list, call move.doMove(u), and if the result is not null, add it to a list of the state's children.
• We call this process "expanding" the state's vertex in the tree.
• Expanding a vertex u for a dynamic search tree is analogous to looking up the adjacency list Adj[u] for a static graph.