We calculate the decay constant ratios f c=fJ= and f b=f . In the calculation we take into account the mock meson structures of the mesons, as well as the di erence of the wave functions at origin of the vector and pseudoscalar mesons studied by Ahmady and Mendel. We nd that the di erent spin structures of the mesons much a ect the ratios. We incorporate our results in the prediction of the bra...

recently, the algebraic theory of mv -algebras is intensively studied. in this paper, we extend the concept of derivation of $mv$-algebras and we give someillustrative examples. moreover, as a generalization of derivations of $mv$ -algebraswe introduce the notion of $f$-derivations and $(f; g)$-derivations of $mv$-algebras.also, we investigate some properties of them.