<s>
where	O
and	O
form	O
a	O
pair	O
of	O
topological	B-Architecture
vector	I-Architecture
spaces	I-Architecture
that	O
are	O
in	O
duality	B-Algorithm
,	O
is	O
a	O
bilinear	O
mapping	O
and	O
is	O
the	O
Kronecker	O
delta	O
.	O
</s>
<s>
A	O
biorthogonal	B-Algorithm
system	I-Algorithm
in	O
which	O
and	O
is	O
an	O
orthonormal	B-Algorithm
system	I-Algorithm
.	O
</s>
<s>
and	O
then	O
is	O
a	O
biorthogonal	B-Algorithm
system	I-Algorithm
.	O
</s>
