Let V be a finite dimensional real vector spaces of dimension n with basis $e_i$, $1 \leq i \leq n$. We denote by $x_i$ the coordinate function, namely the function that associate to $v = v_1e_1+...+v_ne_n \in V $ the element $v_i$.
Let P be another finite dimensional real vector space. We set $W= V \oplus P $ and denote by $C^{-\infty}(W)$ the set of generalized function over W.
I find the following statement in the proof of lemma 21 in the article by Kumar and Vergne on equivariant cohomology with generalized coefficients :
If $x_if(x+y)=0$, for all i. Then f is the product of the $ \delta$-function on V with a generalized function on P .
Why this is true?
Any help would be greatly appreciated.