Joshua Grochow<p>Is there a term (like '<a href="https://mathstodon.xyz/tags/nilpotent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>nilpotent</span></a>') for a <a href="https://mathstodon.xyz/tags/linear" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>linear</span></a> operator L on an infinite-dim space such that in some basis, L is strictly upper triangular?</p><p>E.g. L=multiplication by x acting on the polynomial ring k[x].</p><p><a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/algebra" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>algebra</span></a></p>