Preface -- Singular Support of a Vertex Algebra and the Arc Space of its Associated Scheme -- On Cacti and Crystals -- Quotients for Sheets of Conjugacy Classes -- About Polynomiality of the Poisson Semicentre for Parabolic Subalgebras -- On Dynkin Gradings in Simple Lie Algebras -- Multiplicative Slices, Relativistic Toda, and Shifted Quantum Affine Algebras -- Some Properties of Orbital Varieties in Extremal Nilpotent Orbits -- On Involutions in the Weyl Group and B-Orbit Closures in the Orthogonal Case -- Proper Self-Similar Triangle Tiling and Representing Weight Diagrams in the Plane -- Closures of On-Orbits in the Flag Variety for GLn -- On the Spin Calogero-Sutherland Model at Infinity -- Semi-Direct Products Involving Sp2n or Spinn with Free Algebras of Symmetric Invariants -- Primitive Ideals of U(sl(∞)) and The Robinson‐Schensted Algorithm at Infinity -- Prime Spectra of Abelian 2-Categories and Categorifications of Richardson Varieties.