Branes and symmetries for N = 3 S-folds

A bstract We describe the higher-form and non-invertible symmetries of 4d N N = 3 S-folds using the brane dynamics of their holographic duals. In cases with enhancement to N N = 4 supersymmetry, our analysis reproduces the known field theory results of Aharony, Seiberg and Tachikawa, and is compatible with the effective action recently given by Bergman and Hirano. Likewise, for two specific N N = 3 theories for which Zafrir has conjectured N N = 1 Lagrangians our results agree with those implied by the Lagrangian description. In all other cases, our results imply novel predictions about the symmetries of the corresponding N N = 3 field theories.