Base change between canonical basis and path basis

Almost 30 years ago Littelmann conjectured that there is a unitriangular base change between the dual canonical basis and the path vector basis for all symmetrizable Kac-Moody Lie algebras. In this paper we give a positive answer to the conjecture for the case of classical Lie algebras and type $G_2$, when the path model is given by standard Young tableaux.