Comment on "Validity of Feynman's prescription of disregarding the Pauli principle in intermediate states" - art. no. 016101

In a recent paper. Coutinho, Nogami, and Tomio [Phys. Rev. A 59, 2624 (1999 )] presented an example in which, they claim, Feynman's prescription of dis regarding the Pauli principle in intermediate states of perturbation theory fails. We show that, contrary to their claim, Feynman's prescription is co nsistent with the exact solution of their example.