directed acyclic graph

Paths in a graph show how to travel from a start node to a destination. Node-based paths list the nodes visited but cannot distinguish parallel edges with different weights. Edge-based paths use tuples of start node, destination node and weight so every route is exact. Simple paths repeat no edges or vertices. Cyclic paths start and end on the same node and prove the graph is cyclic. A DAG is a directed acyclic graph with no cycles. These ideas prepare for graph algorithms.