  Tree-like tableaux are certain fillings of Ferrers diagrams originally
introduced by Aval et al., which are in simple bijections with permutation
tableaux coming from Postnikov's study of totally nonnegative Grassmanian and
alternative tableaux introduced by Viennot. In this paper, we confirm two
conjectures of Gao et al. on the refined enumeration of non-occupied corners in
tree-like tableaux and symmetric tree-like tableaux via intermediate structures
of alternative tableaux, linked partitions, type $B$ alternative tableaux and
type $B$ linked partitions.
