  Let $a,b$ be two positive integers such that $a \le b$ and $a \equiv b$ (mod
$2$). We say that a graph $G$ has an $(a,b)$-parity factor if $G$ has a
spanning subgraph $F$ such that $d_{F}(v) \equiv b$ (mod $2$) and $a \le
d_{F}(v) \le b$ for all $v \in V (G)$. In this paper, we provide a tight
spectral radius condition for a graph to have $(a,b)$-parity factors.

Combinatorics