  In a recent paper, de Freitas et al. [Phys. Rev. E 61, 6330 (2000)] presented
simulational results for the critical exponents of the two-species
reaction-diffusion system A + B -> 2B and B -> A in dimension d = 1. In
particular, the correlation length exponent was found as \nu = 2.21(5) in
contradiction to the exact relation \nu = 2/d. In this Comment, the symmetry
arguments leading to exact critical exponents for the universality class of
this reaction-diffusion system are concisely reconsidered.
