On vertices enforcing a Hamiltonian cycle
Igor Fabrici, Erhard Hexel, Stanislav Jendrol′ · Discussiones Mathematicae Graph Theory · 2012
defined to be the smallest cardinality of an H-force set of G.In the paper the study of this parameter is introduced and its value or a lower bound for outerplanar graphs, planar graphs, k-connected graphs and prisms over graphs is determined.