Toughness and binding numbers
The toughness and binding number of a graph are two measures of how its edges are distributed and how well the graph is connected. We survey the main properties of toughness and binding number, and study the conditions upon them that ensure the existence of factors and cycles.
The concept of toughness was introduced by Václav Chvátal  in 1973. As he wrote, toughness ‘measures in a simple way how tightly various pieces of graph hold together’.
The origin ...