We show that certain submanifolds of generalized complex manifolds (“weak
branes”) admit a natural quotient which inherits a generalized complex
structure. This is analog to quotienting coisotropic submanifolds of symplectic
manifolds. In particular, Gualtieri’s generalized complex submanifolds
(“branes”) quotient to space-filling branes. Along the way, we perform
reductions by foliations (i.e., no group action is involved) for exact Courant
algebroids—interpreting the reduced ˇSevera class—and for Dirac structures.