For a quasidifferentiable function f defined on R 2 , it is proved, in the sense of Demyanov and Rubinov, that the following assertion [∂f (x),∂f (x)]∈Df (x) (∂f (x) + ∂f (x)), [∂f (x),∂f (x)]∈Df (x) (∂f (x) − ∂f (x)) ∈ Df (x) in this paper, where Df (x) denotes the set of all quasidifferentials of f at x. It is shown that this way can be viewed as an approach to determining or choosing a repre...

modern world revolutions have created some instruments known as ‎quasi-negotiable instruments which are different from negotiable ones, ‎despite having some similarities to them. commercial custom recognizes ‎them as quasi-negotiable instruments. the principle is that we don’t ‎need new legal regime for this new category because they are right in ‎personam when they are created and rights in re...