Wirtinger-Sobolev Isoperimetric Constants
Constants 
such that
where
is a real-valued smooth function on a region 
satisfying some Boundary Conditions.
References
Finch, S. ``Favorite Mathematical Constants.'' http://www.mathsoft.com/asolve/constant/ws/ws.html
- Deducible
- Deep Theorem
- Defective Matrix
- Defective Number
- Deficiency
- Deficient Number
- Definable Set
- Defined
- Definite Integral
- Degenerate
- Degree
- Degree (Algebraic Surface)
- Degree (Map)
- Degree of Freedom
- Degree (Polynomial)
- Degree Sequence
- Degree (Vertex)
- Dehn Invariant
- Dehn's Lemma
- Dehn Surgery
- de Jonquières Theorem
- de Jonquières Transformation
- Del
- de la Loubere's Method
- Delannoy Number