β ▁if ▁and ▁only ▁if ▁α ▁c - commands ▁ β , ▁and ▁α ▁and ▁ β ▁core fer . ▁ ▁Consider ▁the ▁sentence ▁" J oh ni ▁saw ▁his i ▁mother ", ▁which ▁is ▁diagram med ▁below ▁using ▁simple ▁phrase ▁structure ▁trees . ▁ ▁The ▁N P ▁" John " ▁c - commands ▁" his " ▁because ▁the ▁first ▁parent ▁of ▁the ▁N P , ▁S , ▁contains ▁" his ". ▁ ▁" John " ▁and ▁" his " ▁are ▁also ▁core fer ential ▁( they ▁refer ▁to ▁the ▁same ▁person ), ▁therefore ▁" John " ▁bind s ▁" his ". ▁ ▁On ▁the ▁other ▁hand , ▁in ▁the ▁un gram mat ical ▁sentence ▁"* The ▁mother ▁of ▁Joh ni ▁lik es ▁himself i ", ▁" John " ▁does ▁not ▁c - command ▁" him self ", ▁so ▁they ▁have ▁no ▁binding ▁relationship ▁despite ▁the ▁fact ▁that ▁they ▁core fer . ▁ ▁The ▁importance ▁of ▁binding ▁is ▁shown ▁in ▁the ▁gram mat ical ity ▁or ▁un gram mat ical ity ▁of ▁the ▁following ▁sentences : ▁▁ ▁* J oh ni ▁saw ▁him i . ▁ ▁Joh ni ▁saw ▁himself i . ▁ ▁* H im self i ▁saw ▁Joh ni . ▁▁ ▁* J oh ni ▁saw ▁Joh ni . ▁ ▁Binding ▁is ▁used , ▁along ▁with ▁particular ▁binding ▁principles , ▁to ▁explain ▁the ▁un gram mat ical ity ▁of ▁statements ▁ 1 , ▁ 3 , ▁and ▁ 4 . ▁The ▁applicable ▁rules ▁are ▁called ▁Binding ▁Princi ple ▁A , ▁Binding