Information Technology Reference
In-Depth Information
20. receive
X.sup
j
from the sites
S
j
,
where
S
j
∉
X.large_sites
;
n
i
Σ
21.
X.sup
=
X.sup
i
;
=
22.
if X.sup
≧
s
×
D
i
then
insert
X
into
G
i
(
k
)
; }
23. broadcast
G
i
(
k
)
;
24. receive
G
j
(
k
)
from all other sites
S
j
, (
j
¬
i
);
n
i
G
G
i
(
k
)
.
25.
L
(
k
)
=
26. divide
L
(
k
)
into
GL
i
(
k
)
, (
i
= 1,…,
n
);
27.return
L
(
k
)
.
S
i
is initially a “home site” of the
candidate sets, then as polling site to respond the request from other sites. Finally,
S
i
is transformed into remote site to support local support count to other polling
site. We explain the above procedure according to different roles and activities of
steps in FDM-LP algorithm as follows.
(1) Home site: generate candidate itemsets and submit to polling sites (lines
1-10).
(2) Polling site: receive candidate itemsets and send poll requests (lines 11-17).
(3) Remote site: return support count to polling site (line 18).
(4) Polling site: receive support count and find out large itemsets (lines19 -23)
(5) Home site: receive large itemsets (lines 24 - 27)
In the following discuss, by using two different global pruning technologies,
shows two more refined editions of FDM-LP algorithm.
Algorithm 12.7
FDM-LUP algorithm, FDM algorithm of local and upper bound
pruning
In FDM-LP algorithm, firstly, every
Method:
The program fragment of FDM-LUP is obtained from FDM-LP by inserting the
following condition (line 7.1) after line 7 of Algorithm 12.6.
