- reachable set of singular system
- reaching law
- reaction-diffusion equation
- reaction-diffusion equations system
- reaction-diffusion logistic equation
- totally convex set
- totally defectless valuation
- totally defectless valuation ring
- totally disconnected space
- totally geodesic map
- totally geodesic submanifold
- totally geodesic submanifold of symmetric spaces
- totally inaccessible time
- totally isotopic subspace
- totally isotropic subspace
- totally isotropic subspace
- totally nonlinear partial differential equation
- totally nonnegative matrix
- totally ordered group
- totally ordered module
- totally ordered relation
- totally ordered set
- totally ordered set
- totally orthogonal system
- totally orthonormal system in L2