Definition
Dual Heuristic
A dual heuristic is a heuristic used to obtain strong lower bounds (for minimisation problems) or upper bounds (for maximisation problems) on the optimal solution value. Unlike traditional primal heuristics that aim to find good, feasible solutions, a dual heuristic operates on a related problem, known as the dual problem, to guide the search and prune the search space more effectively.
They are used in branch and bound algorithms.