Structural properties and edge choosability of planar graphs without 4-cycles

Some structural properties of planar graphs without 4-cycles are investigated. By the structural properties, it is proved that every planar graph image without 4-cycles is edge-image-choosable, which perfects the result given by Zhang and Wu: If image is a planar graph without 4-cycles, then image is edge-image-choosable, where image if image, and otherwise image.