Critical Pairs for Mixed Restricted Sumsets in Prime Fields

Let $p$ be an odd prime and let $A,B\subseteq\mathbb{F}_p$ be nonempty and distinct, with $|A|\ge |B|$. We give a complete classification of the pairs for which the mixed restricted sumset $A\mathbin{\widehat+} B=\{x+y:x\in A,\ y\in B,\ x\ne y\}$ has size $\min\{p,|A|+|B|-2\}$. The main new contribu