The ring of $n \times n$ matrices over $\mathbb Q$ whose entries below the diagonal are zero.
Keywords matrix ring
| Name | Measure | |
|---|---|---|
| cardinality | $\aleph_0$ | |
| composition length | left: $n(n+1)/2$ | right: $n(n+1)/2$ |
| global dimension | left: 1 | right: 1 |
| Krull dimension (classical) | 0 |
| Name | Description |
|---|---|
| Left singular ideal | $\{0\}$ |
| Right singular ideal | $\{0\}$ |