Linear covariance for nonlinear formal representations of the Poincaré group in \(2+1\) dimensions (Q916805)

The purpose of this note is to show that nonlinear representations of the Poincaré group P(2,1) as previously defined [J. Math. Phys. 28, 1972- 1977 (1987; Zbl 0632.22017)] act linearly on the fields (a fact called ``linear covariance'') provided the classical relativistic fields are defined suitably. The presentation of the argument and the subsequent discussion of the result is very confusing: it lacks both physical intuition and mathematical precision.