# Problem understanding Wigner's 1939 paper

if subspace A is invariant with respect to a linear operator, is it true that A is invariant with respect to the inverse operator? if not I think threre is a mistake in Wigners paper in "B. Some immediate simplifications" page 13

I'm sorry it's my mistake, I didn't read well. At the begining of the paragraph he says that the subspace is invariant under all lorentz transformation then it must be invariant for $D(L^{-1})$ too

A. Neumaier
if subspace A is invariant with respect to a linear operator, is it true that A is invariant with respect to the inverse operator?
Yes, if the linear operator is invertible and maps A onto A.

Last edited:
Samy_A