surface, which surrounds a copy of the bond-lattice. The copolymer chains then have conformations with one (A) species stretching towards the bond-lattice, the junction between blocks residing on the dividing surface, and the other (B) species stretching towards the minimal surface. In the G phase the diamond lattice is replaced by a three-fold coordinated lattice, and the surface is replaced by the gyroid minimal surface discovered by Schoen in 1970 [@schoen70], in which the two interpenetrating G volumes are chiral enantiomers of one another. For the P phase the bond lattice is six-fold coordinated (Figure \[fig:skeletons\]) and the candidate partitioning surface is the Schwartz P minimal surface.

There is no compelling reason to choose a minimal surface for the partitioning surface. However, minimal surfaces solve the variational problem of minimizing surface area with zero pressure across the interface. If the diblock phase is in fact partitioned into two equivalent connected regions, then by symmetry there can be no net pressure exerted across the dividing surface that separates the two equivalent disjoint connected regions. So a minimal surface is reasonable, but by no means certain, since there is no obvious area energy to minimize.

=2.5truein

=2.5truein

=2.5truein

The P, D, and 