Some definitions:
1. FIG vertices and edges is
2. The degree of vertex (degree of vertex): the number of edges to this point as the vertex.
FIG 3. is a communication (connective): any two vertices, edges there is a path linking them
4.G 'is a subgraph of G: G' vertex set is a subset of a set of vertices of G, a set of edges in G 'is G in the side of the subset of the set.
5. FIG embedded R & lt D space (Embedded in R & lt D ), each vertex in FIG R & lt D has a coordinate space.
6. The plan view of (planar graph): FIG vertices and edges may be embedded R & lt 2 space, his side are disjoint. Each plan can be represented by a straight line plan (straight-line plane graph).
7. Triangulation: is straight all the faces of the triangular plan.
8.Delauney Triangulation: any of a circumcircle of the triangle does not contain other vertex.
9. mesh (Mesh): R & lt . 3 embedded in a straight line in FIG.
10. The boundary edge (Boundary edge): Only a surface adjacent the edge.
11. Conventional edge (regular edge): There are two sides adjacent the surface.
12. Singular (singular edge): more than two adjacent side edges.
13. Grid closed (closed mesh): free boundary edge of the grid.
14. The grid manifold (manifold mesh): Singular free mesh.
15. Euler's formula:
v+f-e=2(c-g)-b
16. The direction of the plane defined by the right hand or left-hand rule rule definition also defines surface normal.
FIG 17 is a straight line oriented (orientability): can select the direction of each face of the graph, such that each side has two directions. Möbius strip or Klein bottle is non-directional.
18. developable grid: mesh may be embedded in R & lt 2 twist does not occur.