简介:Globalpropertyisthenecessaryconditionwhichmustbesatisfiedbytheprovableformulas.Itcanhelptofindoutsomeunprovableformulathatdoesnotsatisfysomeglobalpropertybeforeprovingitusingformalautomatedreasoningsystems,thustheefficiencyofthewholesystemisimproved.ThispaperpresentssomeglobalpropertiesofvalidformulasinmodallogicK.Suchpropertiesarestructurecharactersofformulas,sotheyaresimpleandeasytocheck.Atthesametime,someglobalpropertiesofKunsatisfiableformulasetarealsogiven.