Implied Spaces by Walter Jon Williams

Implied spaces are those unintended elements that exist, just because something has to fill the void between the spaces that are deliberately created. This metaphor starts with architecture, but the swordsman and scholar Aristide extends it to the created worlds, societies, and pocket universes of post-singularity humanity. He discovers a plot emanating from the implied spaces that threatens to destroy all that he created, from a nemesis who can match or exceed Aristide's nearly god-like powers.