Hook criterion in a beta set
= Hook criterion in a beta set
Let $X=\{h_1,\ldots,h_m\}$ be a beta set and let $H_i(\lambda)$ be the hook lengths in row $i$. Then
$$
h\in H_i(\lambda)
\quad\Longleftrightarrow\quad
h_i-h\geq0\text{ and }h_i-h\notin X.
$$
Thus hooks are exactly bead-gap pairs on the partition abacus.