
arXiv: 1308.4321
The obstacle number is a new graph parameter introduced by Alpert, Koch, and Laison (2010). Mukkamala et al. (2012) show that there exist graphs with $n$ vertices having obstacle number in $\Omega(n/\log n)$. In this note, we up this lower bound to $\Omega(n/(\log\log n)^2)$. Our proof makes use of an upper bound of Mukkamala et al. on the number of graphs having obstacle number at most $h$ in such a way that any subsequent improvements to their upper bound will improve our lower bound.
Computational Geometry (cs.CG), FOS: Computer and information sciences, Extremal problems in graph theory, Discrete Mathematics (cs.DM), Graph representations (geometric and intersection representations, etc.), FOS: Mathematics, Mathematics - Combinatorics, Computer Science - Computational Geometry, Combinatorics (math.CO), Computer Science - Discrete Mathematics
Computational Geometry (cs.CG), FOS: Computer and information sciences, Extremal problems in graph theory, Discrete Mathematics (cs.DM), Graph representations (geometric and intersection representations, etc.), FOS: Mathematics, Mathematics - Combinatorics, Computer Science - Computational Geometry, Combinatorics (math.CO), Computer Science - Discrete Mathematics
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