D4-brane

This entry is about a D-brane species in string theory. For the items in the ADE-classification of name D4, see there. The D-brane of dimension in type IIA string theory. Khovanov homology has long been expected to appear as the observables in a 4-dimensional TQFT in higher analogy of how the Jones polynomial arises as an observable in 3-dimensional Chern-Simons theory. For instance for a cobordism between two knots there is a natural morphism between the Khovanov homologies associated to the...