Graph Theory, Lecture 1: Introduction

Introductory remarks: why choose graph theory at university? Wire cube puzzle; map colouring problem; basic definitions. Euler's Königsberg bridges theorem with proof (Chapter 1.8). Based on R.Diestel, Graph Theory, Springer GTM173, 6th edition 2025. Ebooks available at https://diestel-graph-theory.com under links "Standard eBook" and "Professional Edition".