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For a graph G and a positive integer k, a k-list assignment of G is a function L on the vertices of G such that for each vertex v is an element of V(G), |L(v)| >= k. Let s be a nonnegative integer. Then L is a (k, k + s)-list assignment of G if |L(u) boolean OR L(v)| >= k + s for each edge uv. If for each (k, k + s)-list assignment L of G, G admits a proper coloring phi such that phi(v) is an element of L(v) for each v is an element of V(G), then we say G is (k, k + s)-choosable. This refinement of choosability is called choosability with union separation by Kumbhat et al. (2018), who showed that all planar graphs are (3, 11)-choosable and (4, 9)-choosable. In this paper, we prove that every triangle-free planar graph is (3, 7)-choosable. We also prove that every planar graph with girth at least 5 is (2, 7)-choosable. (c) 2020 Elsevier B.V. All rights reserved.
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DISCRETE MATHEMATICS
ISSN: 0012-365X
Year: 2020
Issue: 12
Volume: 343
0 . 8 7
JCR@2020
0 . 7 0 0
JCR@2023
ESI Discipline: MATHEMATICS;
ESI HC Threshold:50
JCR Journal Grade:3
CAS Journal Grade:3
Cited Count:
WoS CC Cited Count: 0
SCOPUS Cited Count: 4
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 1
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