  The adaptive BDDC method is extended to the selection of face constraints in
three dimensions. A new implementation of the BDDC method is presented based on
a global formulation without an explicit coarse problem, with massive
parallelism provided by a multifrontal solver. Constraints are implemented by a
projection and sparsity of the projected operator is preserved by a generalized
change of variables. The effectiveness of the method is illustrated on several
engineering problems.
