2-Categories, 4d state-sum models and gerbes
2-Degenerate Bertrand curves in Minkowski spacetime
2-Frame flow dynamics and hyperbolic rank rigidity in nonpositive curvature
2-Riemannian manifolds
2-Ruled Calibrated 4-folds in R^7 and R^8
2-step nilpotent Lie groups arising from semisimple modules
2nd-order symmetric Lorentzian manifolds I: characterization and general results