The Drazin inverses of infinite triangular matrices and their linear preservers

Abstract

We consider the ring of all infinite $(N \times N)$ upper triangular matrices over a field $F$. We give a description of elements that are Drazin invertible in this ring. In the case where $F$ is such that $\mathrm{c}\mathrm{h}\mathrm{a}\mathrm{r}(F) \not = 2$ and $| F| > 4$, we find the form of linear preservers for the Drazin inverses.