Ivy uses notions and algorithms from Graph Theory and applies them towards mesh geometry exploration.
With Ivy for Grasshopper you can segment any given 2-manifold mesh for purposes ranging from flat sheet fabrication to visualization and further editing.
In order to facilitate the controlled segmentation and other subsequent operation Ivy uses a graph representation of the mesh where the mesh faces are the graph nodes and the mesh edges are edges in the graph. Graph edges and nodes have a property called weight that can represent any numeric value derived from any source be it geometric or not. Using these values and graph traversing algorithms various mesh segmentations are possible.
Fabrication through unfolding is also facilitated through segmentation and edge cuts that transform the cyclic graph into a tree graph.
More information can be found here
Video tutorials on how to use Ivy are available here .