# Glossary

This page gives definitions of the words commonly used in the RINGMesh project.

## Base objects

• Point - A position in space: (x,y) in 2D or (x,y,z) in 3D.
• Segment - Part of a line bounded by two distinct points.
• Polygon - Part of a plane bounded by a finite number of non-intersecting segments closing in a loop.
• Polyhedron - Part of a space bounded by a finite number of non-intersecting polygons defining an interior and an exterior.

• N-simplex - The convex-hull of N+1 points

• Point: 0-simplex
• Segment: 1-simplex
• Triangle: 2-simplex
• Tetrahedron: 3-simplex

## Elements of a mesh

• Mesh cell - A polyhedron of a volumetric mesh.
• Mesh polygon - A polygon of a surface mesh.
• Mesh edge - A segment of a linear mesh.
• Vertex - A corner point of a mesh cell, a mesh polygon or a mesh edge.

• Facet - A (N-1) boundary of a mesh element

• A face of a mesh cell
• An edge of a mesh polygon
• A vertex of a mesh edge

## Mesh: Set of elements

• Structured mesh - A mesh with regular connectivity meaning that each vertex is connected to the same number of vertices.
• Unstructured mesh - A mesh with any connectivity between vertices.

## Notion

• Topology - Connectivity information between entities.