Abstrakt
The chapter provides an overview of the major discoveries in combinatorics between the world wars. At that time, combinatorics was already a well-established mathematical discipline, with new results being published in respected journals including the Acta Mathematica, American Journal of Mathematics, or Annals of Mathematics.
The motivation for studying combinatorial problems frequently came from other disciplines such as set theory, group theory, linear algebra, logic or number theory. Recreational mathematics was an important source of inspiration for research in graph theory, and this fact contributed to the bad reputation of graph theory as a science of trivial problems.
However, the publication of the first textbook of graph theory in 1936, which presented it as a completely rigorous discipline with applications in linear algebra and set theory, helped to change this attitude. In the meanwhile, some important results that are now classified as belonging to graph theory were formulated in the language of topological structures.
Finally, one should not forget that numerous developments in combinatorics grew out of purely practical problems, such as the design of experiments, construction of electricity networks, or the enumeration of chemical compounds.