A tree is a connected graph with no cycles or self-loops. Its nodes are linked by hierarchical edges, so every node belongs to one connected, cycle-free structure. section 3.1
Trees are a specialized case of graphs. Distinguish them from directed graphs, multigraphs, weighted graphs, and general acyclic graphs by checking connectivity, cycles, and self-loops. section 3.1
Listing 3.4 Creating an acyclic graph using NetworkX
import networkx as nx import matplotlib.pyplot as plt graph = nx.DiGraph() nodes = list(range(5)) edges = [(0,1), (0,2),(4,1),(1,2),(2,3)] graph.add_nodes_from(nodes) graph.add_edges_from(edges) nx.draw_networkx(graph, nx.kamada_kawai_layout(graph), with_labels=True, font_color='w') plt.show() nx.is_directed_acyclic_graph(graph) #1 #1 Check if the graph is acyclic.
Inspect a NetworkX acyclic-graph construction and its directed-cycle check as a nearby comparison for tree structure. section 3.1
