This example shows a directional knowledge graph mapping the hierarchical relationships between computer science concepts, from a root topic down through nested subtopics like information retrieval and speech recognition, with colored nodes indicating depth levels. The visualization builds its layout from a dataset using d3.hierarchy-style traversal functions that compute descendant nodes and link pairs, then renders the structure as an SVG with arrowhead markers on each directed edge. Node colors are assigned via d3.scaleOrdinal, while the graph itself relies on d3.v4’s selection and data-binding methods to position the nodes and paths dynamically.