This entry formalises the fast iterative algorithm for computing dominators due to Cooper, Harvey and Kennedy. It gives a specification of computing dominators on a control flow graph where each node refers to its reverse post order number. A semilattice of reversed-ordered list which represents dominators is built and a Kildall-style algorithm on the semilattice is defined for computing dominators. Finally the soundness and completeness of the algorithm are proved w.r.t. the specification.