The field of graph theory has been around since 1736, when Leonhard Euler published an article on the subject of the Seven Bridges of Königsberg (in Prussia, today’s Kaliningrad in Russia).

D. B. West, Introduction to Graph Theory, Prentice Hall 2001 R. Diestel, Graph Theory, Springer 2010. N. L. Biggs, Discrete Mathematics, OUP 2004 J.A.Bondy and U.S.R. Murty, Graph Theory with ...

Maurice M. Tatsuoka, Graph Theory and Its Applications in Educational Research: A Review and Integration, Review of Educational Research, Vol. 56, No. 3 (Autumn, 1986), pp. 291-329 ...

This guarantees that every graph has an even subgraph that’s at least half as big as the original. But how big an odd subgraph can be has been an open research question in graph theory for over 60 ...