Kernelled Quasidifferential for a Quasidifferentiable Function in Two-Dimensional Space

For a quasidifferentiable function defined on two-dimensional space in the sense of Demyanov and Rubinov it is proved that the pair of the intersection of the sums of the subdifferentials and superdifferentials for all quasidifferentials, and the intersection of the differences of the subdifferentials and superdifferentials for all quasidifferentials is a quasidifferential of the function. It is shown that this way can be viewed as an approach to determining or choosing a representative for the equivalent class of quasidifferentials for a quasidifferentiable function at a point, in the two-dimensional case.