Database Reference
In-Depth Information
Fig. 4.3
Process architecture
Then
,
the denotational semantics for the query rewriting algorithms exp
(q) and
G
unf
(q)
,
for a query expansion and query unfolding
,
respectively
,
are given by two
functions on the set
M
L
G
,
x
of queries with variables in
x
over the global schema
G
:
1.
α
∗
MakeOperads
∀
x
exp
r
q
(
x
)
(_)
⇒
G
in
◦
α
∗
MakeOperads
∀
x
(_ )
⇒
r
q
(
x
)
=
Tf
OP
DB
ret(
I
,D),Tret(
I
,D)
,
◦
f
in
:
L
G
,
x
→
such that for each query q(
x
)
∈
L
G
,
x
,
α
∗
MakeOperads
∀
x
exp
q(
x
)
⇒
r
q
(
x
)
G
α
∗
MakeOperads
∀
x
q(
x
)
⇒
r
q
(
x
)
Tf
OP
=
◦
in
◦
f
in
:
ret(
I
,D)
→
Tret(
I
,D)
is a morphism in
DB
.
2.
α
∗
MakeOperads
∀
x
unf
r
q
(
x
)
(_)
⇒
M
α
∗
MakeOperads
∀
x
(_ )
r
q
(
x
)
Tf
O
M
◦
=
⇒
◦
f
M
:
L
G
,
x
→
DB
(D,T D),
