TY - GEN
T1 - On max-clique for intersection graphs of sets and the hadwiger-debrunner numbers
AU - Keller, Chaya
AU - Smorodinsky, Shakhar
AU - Tardos, Gábor
N1 - Publisher Copyright:
Copyright © by SIAM.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Let HDd(p, q) denote the minimal size of a transversal that can always be guaranteed for a family of compact convex sets in Rd which satisfy the (p, q)-property (p ≥ q ≥ d + 1). In a celebrated proof of the Hadwiger-Debrunner conjecture, Alon and Kleitman proved that HDd(p, q) exists for all p ≥ q ≥ d + 1. Specifically, they prove that HDd(p, d + 1) is O(pd2+d). This paper has two parts. In the first part we present several improved bounds on HDd(p, q). In particular, we obtain the first near tight estimate of HDd(p, q) for an extended range of values of (p, q) since the 1957 Hadwiger-Debrunner theorem. In the second part we prove a (p, 2)-theorem for families in R2 with union complexity below a specific quadratic bound. Based on this, we introduce a polynomial time constant factor approximation algorithm for MAX-CLIQUE of intersection graphs of convex sets satisfying this property. It is not likely that our constant factor approximation can be improved to a PTAS as MAX-CLIQUE for intersection graphs of fat ellipses is known to be APX-HARD and fat ellipses have sub-quadratic union complexity.
AB - Let HDd(p, q) denote the minimal size of a transversal that can always be guaranteed for a family of compact convex sets in Rd which satisfy the (p, q)-property (p ≥ q ≥ d + 1). In a celebrated proof of the Hadwiger-Debrunner conjecture, Alon and Kleitman proved that HDd(p, q) exists for all p ≥ q ≥ d + 1. Specifically, they prove that HDd(p, d + 1) is O(pd2+d). This paper has two parts. In the first part we present several improved bounds on HDd(p, q). In particular, we obtain the first near tight estimate of HDd(p, q) for an extended range of values of (p, q) since the 1957 Hadwiger-Debrunner theorem. In the second part we prove a (p, 2)-theorem for families in R2 with union complexity below a specific quadratic bound. Based on this, we introduce a polynomial time constant factor approximation algorithm for MAX-CLIQUE of intersection graphs of convex sets satisfying this property. It is not likely that our constant factor approximation can be improved to a PTAS as MAX-CLIQUE for intersection graphs of fat ellipses is known to be APX-HARD and fat ellipses have sub-quadratic union complexity.
UR - http://www.scopus.com/inward/record.url?scp=85016177978&partnerID=8YFLogxK
U2 - 10.1137/1.9781611974782.148
DO - 10.1137/1.9781611974782.148
M3 - Conference contribution
AN - SCOPUS:85016177978
T3 - Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms
SP - 2254
EP - 2263
BT - 28th Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2017
A2 - Klein, Philip N.
PB - Association for Computing Machinery
T2 - 28th Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2017
Y2 - 16 January 2017 through 19 January 2017
ER -