DP-coloring as a generalization of list-coloring,was introduced by Dvořák and Postle in 2018.Using DP-coloring,they proved that every planar graph without cycles of lengths 4 to 8 is 3-choosable.In this paper,using DP-coloring,we prove that every planar graph without 4-,6-and special 9-cycles is 3-choosable.
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