We proved that every planar triangle-free graph of order n has a subset of vertices that induces a forest of size at least (71n + 72)/128. This improves the earlier work of Salavatipour (2006). We also pose some questions regarding planar graphs of higher girth.
机构:
INST POLITECN NACL,CTR INVEST & ESTUDIOS AVANZADOS,DEPT MATEMAT,MEXICO CITY 07000,DF,MEXICOINST POLITECN NACL,CTR INVEST & ESTUDIOS AVANZADOS,DEPT MATEMAT,MEXICO CITY 07000,DF,MEXICO