Proposition Recursively regular subdivisions are a superset of the regular subdivisions and a subset of the acyclic ones Proof Assume that it exists a cycle in a recursively regular subdivision. We can assume that the cycle belongs to more than one cell of the FRC and apply recursion otherwise. Then, the FRC cannot be regular, since a cycle cannot be destroyed by means of merging cells.
Proposition There is a 5-dimensional point set with at least 12 recursively regular triangulations pairwise disconnected and disconnected from any regular triangulation in the graph of flips
Applications Floodlights Homothecies Graph embeddings Spider webs
Floodlights polyhedral fan with n cells
Floodlights n points polyhedral fan with n cells
Floodlights n points one to one polyhedral fan with n cells
Floodlights n points one to one polyhedral fan with n cells covering assignment
Covering fans A polyhedral fan is universally covering if for any point set there exists a covering assignment
Covering fans A polyhedral fan is universally covering if for any point set there exists a covering assignment Theorem (Galperin & Galperin, 1981) Regular fans are universally covering
Covering fans A polyhedral fan is universally covering if for any point set there exists a covering assignment Theorem (Galperin & Galperin, 1981) Regular fans are universally covering Theorem Recursively regular fans are universally covering Cyclic fans are not universally covering
Fans Cyclic Rec. regular Regular
Fans Cyclic Rec. regular Regular Universally covering
Fans Cyclic Rec. regular Regular Universally covering
Fans Cyclic Rec. regular Regular Universally covering
Fans Cyclic Rec. regular Regular Universally covering
Overlapping condition
Overlapping condition
Overlapping condition
Directional graph embeddings → − V = { 1 , ..., n } E ⊂ V × V
Directional graph embeddings → − V = { 1 , ..., n } E ⊂ V × V P = { p 1 , ...p n } ⊂ R d
Directional graph embeddings → − N : − → → R d V = { 1 , ..., n } E ⊂ V × V E − P = { p 1 , ...p n } ⊂ R d
Directional graph embeddings → − N : − → → R d V = { 1 , ..., n } E ⊂ V × V E − P = { p 1 , ...p n } ⊂ R d proper embedding Is there a σ : V ↔ P N ( i, j ) · p i ≥ N ( i, j ) · p j ∀ ( i, j ) ∈ − → E ?
Directional graph embeddings → − N : − → → R d V = { 1 , ..., n } E ⊂ V × V E − P = { p 1 , ...p n } ⊂ R d proper embedding Is there a σ : V ↔ P N ( i, j ) · p i ≥ N ( i, j ) · p j ∀ ( i, j ) ∈ − → E ? A path is always embeddable
Directional graph embeddings → − N : − → → R d V = { 1 , ..., n } E ⊂ V × V E − P = { p 1 , ...p n } ⊂ R d proper embedding Is there a σ : V ↔ P N ( i, j ) · p i ≥ N ( i, j ) · p j ∀ ( i, j ) ∈ − → E ? A path is always embeddable A cycle is not always embeddable
Directional graph embeddings → − N : − → → R d V = { 1 , ..., n } E ⊂ V × V E − P = { p 1 , ...p n } ⊂ R d proper embedding Is there a σ : V ↔ P N ( i, j ) · p i ≥ N ( i, j ) · p j ∀ ( i, j ) ∈ − → E ? A path is always embeddable A cycle is not always embeddable A tree?
Proposition If the graph is the normal graph (or a projection of a subgraph) of a fan and there is a covering assignment for P , there is a proper graph embedding for P . If there is no assignment satisfying OC for... , there is no proper embedding
Proposition If the graph is the normal graph (or a projection of a subgraph) of a fan and there is a covering assignment for P , there is a proper graph embedding for P . If there is no assignment satisfying OC for... , there is no proper embedding Corollary The graph of a polytope is always embeddable.
Homothecies 1,3 1,1 1,2 0,6 0,9 1,5
Homothecies 1,3 1,1 1,2 0,6 0,9 1,5
Homothecies
Homothecies
Homothecies
Homothecies
Recommend
More recommend