What Is a Graph? Simple Graphs, Multigraphs & Pseudographs | Discrete Mathematics §10.1

In 1736 Euler looked at seven bridges in Königsberg and drew the first graph in history — dots for land, lines for bridges. That one act of stripping a map down to "what's connected to what" launched all of graph theory. In this video: the definition of a graph and the first three members of the undirected "zoo," drawn on the board. A graph G = (V, E) is just vertices and edges; a simple graph has at most one edge per pair and no loops (so at most C(n,2) edges); a multigraph allows parallel edges between the same pair; a pseudograph also allows loops. We draw each one and see exactly what changes. Then continue with §10.1 Directed Graphs and the Directed Zoo (next in the playlist). This video is part of Discrete Mathematics · Graphs (§10.1 — Graphs and Graph Models). Full section playlist → linked above / in the description on the channel. Made with the Engineering Simplified method: a calm, two-voice story lesson taught on a chalk-and-board, with every definition and example drawn out step by step. Topic coverage follows Rosen, Discrete Mathematics and Its Applications (Chapter 10).