Finite-dimensional algebras over an algebraically closed field are divided into two
disjoint classes, called tame and wild respectively, by Drozd's tame and wild dichotomy (see [5] and [2]). A tame algebra, roughly speaking, has its n-dimensional
indecomposable modules parametrized by finitely many one-parameter families, for
all natural numbers n, but a wild algebra has more indecomposable modules and
it is considered hopeless to classify them. In [2], Crawley-Boevey showed that all
but finitely many n-dimensional indecomposable modules over a tame algebra are
τ-invariant, for all natural numbers n, and conjectured that the converse would be
true, where τ := DTr is the Auslander–Reiten translation (see [1]) and we call an
indecomposable module X τ-invariant if X ≅ = τX.