Planar Graphs – p. 1
... The cycle C is the boundary of a face for every embedding of G in S 2 if and only if G − C is connected. Proof. If G − C is connected, then for any embedding of G in S 2 , the connected set G − C is contained in one of the two disks bounded by C. The other disk must be a face. Suppose G − C is disco ...
... The cycle C is the boundary of a face for every embedding of G in S 2 if and only if G − C is connected. Proof. If G − C is connected, then for any embedding of G in S 2 , the connected set G − C is contained in one of the two disks bounded by C. The other disk must be a face. Suppose G − C is disco ...
RELATIVE RIEMANN-ZARISKI SPACES 1. Introduction Let k be an
... associated to K as the projective limit of all projective k-models of K. Zariski showed that this topological space, which is now called a RiemannZariski (or Zariski-Riemann) space, possesses the following set-theoretic description: to give a point x ∈ RZK is the same as to give a valuation ring Ox ...
... associated to K as the projective limit of all projective k-models of K. Zariski showed that this topological space, which is now called a RiemannZariski (or Zariski-Riemann) space, possesses the following set-theoretic description: to give a point x ∈ RZK is the same as to give a valuation ring Ox ...
Metric geometry of locally compact groups
... – And the tightly interwoven developments of combinatorial group theory and low dimensional topology, from Dehn to Thurston, and so many others. From 1980 onwards, for all these reasons and under guidance of Gromov, in particular of his articles [Grom–81b, Grom–84, Grom–87, Grom–93], the group commu ...
... – And the tightly interwoven developments of combinatorial group theory and low dimensional topology, from Dehn to Thurston, and so many others. From 1980 onwards, for all these reasons and under guidance of Gromov, in particular of his articles [Grom–81b, Grom–84, Grom–87, Grom–93], the group commu ...
Topic 6 Polygons and Quadrilaterals
... as a ruler, a compass, or geometry software) to investigate the exterior angles of regular polygons. Explain your choice. Draw three regular polygons, each with a different number of sides. Then draw the exterior angles at each vertex of the polygons. b. Make two conjectures about the exterior angl ...
... as a ruler, a compass, or geometry software) to investigate the exterior angles of regular polygons. Explain your choice. Draw three regular polygons, each with a different number of sides. Then draw the exterior angles at each vertex of the polygons. b. Make two conjectures about the exterior angl ...
3-manifold
In mathematics, a 3-manifold is a space that locally looks like Euclidean 3-dimensional space. Intuitively, a 3-manifold can be thought of as a possible shape of the universe. Just like a sphere looks like a plane to a small enough observer, all 3-manifolds look like our universe does to a small enough observer. This is made more precise in the definition below.