In analogy to the classical isomorphism between L (S (R n ) , S ′ (R m )) and S ′ R n+m , we show that a large class of moderate linear mappings acting between the space GS (R n ) of Colombeau rapidly decreasing generalized functions and the space Gτ (R n ) of temperate ones admits generalized integral representations, with kernels belonging to Gτ R n+m . Furthermore, this result contains the classical one in the sense of the generalized distribution equality. (2000)
Mathematics Subject Classification
IntroductionDuring the three last decades, theories of nonlinear generalized functions have been developed by many authors (see [1,11,14,15],...), mainly based on the ideas of J.-F. Colombeau [3,4], which we are going to follow in the sequel. Those theories appear to be a natural continuation of the distributions' one [12,21,22], specially efficient to pose and solve differential or integral problems with irregular data.In this paper, we continue the investigations in the field of generalized integral operators initiated by [18] (recently republished in [19,20]) and carried on by [2,5,9,10,23]. Let us recall that those operators generalize, in the Colombeau framework, the operators with distributional kernels in the space of Schwartz distributions [2]. More specifically, in [5], we proved that any moderate net of linear maps (, that is satisfying some growth properties with respect to the parameter ε, gives rise to a linear map L :and G C (R n ) denote respectively the space of generalized functions and the space of compactly supported ones.) The main result is that L can be represented as a generalized integral operator in the spirit of Schwartz Kernel Theorem.Going further in this direction, we study here the generalization of the classical isomorphism between S ′ (R n+m ) and the space of continuous linear mappings acting between S (R n ) and S ′ (R m ) [22]. Thus, the spaces of generalized functions considered in this paper are the space G S (R n ) of rapidly decreasing generalized functions [7,10,17] and the space G τ (R n ) of tempered generalized functions [4,11,18]: G S (R n ) plays here, roughly speaking, the role of S (R n ) (resp. G C (R n )) in the classical case (resp. in [5]), whereas G τ (R n ) plays the role of S ′ (R m ) (resp. G (R m )) in the classical case (resp. in [5]).
1The main results are the following. First, any kernel H ∈ G τ (R m+n ) gives rise to a new type of linear generalized integral operator acting between G S (R n ) and G τ (R m ) and defined bywhere (H ε ) ε (resp. (f ε ) ε ) is any representative of H (resp. f ) and [·] τ , the class of an element in G τ (R m ). Moreover, the linear map H → H from G τ (R m+n ) to the space of linear maps Proposition 14). This gives the first part of the expected result. Then, new regular subspaces of G S (R n ) and G τ (R m ) are introduced in the spirit of [6]. They are used to define the moderate nets of linear maps, which can be extended to act between G S (R n ) and G τ (R m ) (Proposition 16). Finally, our main result states that ...