“…However, these classes are essentially wider than the space in the definition of the weak convergence in variable space (see ). Therefore, in order to pass to the limit in that integral identities as n → ∞ , we make use the following trick (see Buttazzo and Kogut ). For every fixed , we denote by an arbitrary extension of the functions ( ζ n , u n ) to the whole of space such that the sequence satisfies the properties: …”