Abstract
The NN pi system is studied in a semi-relativistic model (non-relativistic nucleons and relativistic pions) where a Chew-Low Hamiltonian acts in the restricted space spanned by free N+N, N+N+ pi and N+N+2 pi states. The N+N ('absorption') and N+N+2 pi ('production') channels can be eliminated exactly, leaving an effective three-particle problem whose energy-dependent, absorptive interactions are known analytically. These represent a simple but non-trivial example of a mutually consistent set of forces for the NN pi problem, free of overcounting difficulties.