“…However, there is a gap between the theoretically fastest algorithms (i.e., those currently having the best time complexity) and the empirically fastest algorithms (i.e., those currently with the best running time for popular benchmark instances). In the theoretical research on exponential complexity or parameterized complexity of branching algorithms, branch-and-reduce methods, which involve a plethora of branching and reduction rules without using any lower bounds, currently have the best time complexity for a number of important problems, such as Independent Set (or, equivalently, Vertex Cover) [22,4], Dominating Set [10], and Directed Feedback Vertex Set [16]. On the other hand, in practice, branch-and-bound methods that involve problemspecific lower bounds or LP-based branch-and-cut methods, which generate new cuts to improve the lower bounds, are often used.…”