The term faltung is variously used to mean convolution and a function of bilinear forms.
Let 
and 
be bilinear forms
 |  |  |
(1)
|
 |  |  |
(2)
|
and suppose that 
and 
are bounded in ![[p,p^']](/images/equations/Faltung/Inline11.svg)
with bounds 
and 
.
Then
 |
(3)
|
where the series
 |
(4)
|
is absolutely convergent, is called the faltung of 
and 
.
is bounded in ![[p,p^']](/images/equations/Faltung/Inline17.svg)
, and its bound does not exceed 
.
