文摘
We define the anti-forcing number of a perfect matching class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si1.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=dbff034d01584dc47d3fc341e590df84" title="Click to view the MathML source">Mclass="mathContainer hidden">class="mathCode"> of a graph class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si16.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=a7a5f992a194c5ec29fe204a7776299c" title="Click to view the MathML source">Gclass="mathContainer hidden">class="mathCode"> as the minimal number of edges of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si16.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=a7a5f992a194c5ec29fe204a7776299c" title="Click to view the MathML source">Gclass="mathContainer hidden">class="mathCode"> whose deletion results in a subgraph with a unique perfect matching class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si1.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=dbff034d01584dc47d3fc341e590df84" title="Click to view the MathML source">Mclass="mathContainer hidden">class="mathCode">, denoted by class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si19.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=91b4f16174dae78348d01d24193391df" title="Click to view the MathML source">af(G,M)class="mathContainer hidden">class="mathCode">. The anti-forcing number of a graph proposed by Vukičević and Trinajstić in Kekulé structures of molecular graphs is in fact the minimum anti-forcing number of perfect matchings. For plane bipartite graph class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si16.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=a7a5f992a194c5ec29fe204a7776299c" title="Click to view the MathML source">Gclass="mathContainer hidden">class="mathCode"> with a perfect matching class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si1.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=dbff034d01584dc47d3fc341e590df84" title="Click to view the MathML source">Mclass="mathContainer hidden">class="mathCode">, we obtain a minimax result: class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si19.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=91b4f16174dae78348d01d24193391df" title="Click to view the MathML source">af(G,M)class="mathContainer hidden">class="mathCode"> equals the maximal number of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si1.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=dbff034d01584dc47d3fc341e590df84" title="Click to view the MathML source">Mclass="mathContainer hidden">class="mathCode">-alternating cycles of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si16.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=a7a5f992a194c5ec29fe204a7776299c" title="Click to view the MathML source">Gclass="mathContainer hidden">class="mathCode"> where any two either are disjoint or intersect only at edges in class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si1.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=dbff034d01584dc47d3fc341e590df84" title="Click to view the MathML source">Mclass="mathContainer hidden">class="mathCode">. For a hexagonal system class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si26.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=8e335cc633806dd6a00a586dc02b7364" title="Click to view the MathML source">Hclass="mathContainer hidden">class="mathCode">, we show that the maximum anti-forcing number of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si26.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=8e335cc633806dd6a00a586dc02b7364" title="Click to view the MathML source">Hclass="mathContainer hidden">class="mathCode"> equals the Fries number of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si26.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=8e335cc633806dd6a00a586dc02b7364" title="Click to view the MathML source">Hclass="mathContainer hidden">class="mathCode">. As a consequence, we have that the Fries number of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si26.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=8e335cc633806dd6a00a586dc02b7364" title="Click to view the MathML source">Hclass="mathContainer hidden">class="mathCode"> is between the Clar number of class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0166218X15004394&_mathId=si26.gif&_user=111111111&_pii=S0166218X15004394&_rdoc=1&_issn=0166218X&md5=8e335cc633806dd6a00a586dc02b7364" title="Click to view the MathML source">Hclass="mathContainer hidden">class="mathCode"> and twice. Further, some extremal graphs are discussed.