Research output: Contribution to journal › Article › peer-review
k-Sets and rectilinear crossings in complete uniform hypergraphs. / Gangopadhyay, Rahul; Shannigrahi, Saswata.
In: Computational Geometry: Theory and Applications, Vol. 86, 101578, 01.2020.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - k-Sets and rectilinear crossings in complete uniform hypergraphs
AU - Gangopadhyay, Rahul
AU - Shannigrahi, Saswata
PY - 2020/1
Y1 - 2020/1
N2 - In this paper, we study the d-dimensional rectilinear drawings of the complete d-uniform hypergraph K2d d. Anshu et al. (2017) [3] used Gale transform and Ham-Sandwich theorem to prove that there exist Ω(2d) crossing pairs of hyperedges in such a drawing of K2d d. We improve this lower bound by showing that there exist Ω(2dd) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d. We also prove the following results. 1. There are Ω(2dd3/2) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d when its 2d vertices are either not in convex position in Rd or form the vertices of a d-dimensional convex polytope that is t-neighborly but not (t+1)-neighborly for some constant t≥1 independent of d. 2. There are Ω(2dd5/2) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d when its 2d vertices form the vertices of a d-dimensional convex polytope that is (⌊d/2⌋−t′)-neighborly for some constant t′≥0 independent of d.
AB - In this paper, we study the d-dimensional rectilinear drawings of the complete d-uniform hypergraph K2d d. Anshu et al. (2017) [3] used Gale transform and Ham-Sandwich theorem to prove that there exist Ω(2d) crossing pairs of hyperedges in such a drawing of K2d d. We improve this lower bound by showing that there exist Ω(2dd) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d. We also prove the following results. 1. There are Ω(2dd3/2) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d when its 2d vertices are either not in convex position in Rd or form the vertices of a d-dimensional convex polytope that is t-neighborly but not (t+1)-neighborly for some constant t≥1 independent of d. 2. There are Ω(2dd5/2) crossing pairs of hyperedges in a d-dimensional rectilinear drawing of K2d d when its 2d vertices form the vertices of a d-dimensional convex polytope that is (⌊d/2⌋−t′)-neighborly for some constant t′≥0 independent of d.
KW - Affine Gale diagram
KW - Balanced line
KW - Gale transform
KW - k-Set
KW - Rectilinear crossing number
KW - NUMBER
UR - http://www.scopus.com/inward/record.url?scp=85073745709&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/d77626c5-f58f-3220-ae10-f9b3a8454450/
U2 - 10.1016/j.comgeo.2019.101578
DO - 10.1016/j.comgeo.2019.101578
M3 - Article
AN - SCOPUS:85073745709
VL - 86
JO - Computational Geometry: Theory and Applications
JF - Computational Geometry: Theory and Applications
SN - 0925-7721
M1 - 101578
ER -
ID: 49848807