TESI DOCTORAL - La Salle

SERT DHCA (sec.)
PERT DHCA (sec.)
10 0
10 −1
|df A | = 1 , |df D | = 14 , |df R | = 5
ADR ARD DAR DRA RAD RDA flat
DHCA variant
(a) Serial estimated running time
10 −1
|df A | = 1 , |df D | = 14 , |df R | = 5
ADR ARD DAR DRA RAD RDA flat
DHCA variant
(c) Parallel estimated running time
CSPA
EAC
HGPA
MCLA
ALSAD
KMSAD
SLSAD
CSPA
EAC
HGPA
MCLA
ALSAD
KMSAD
SLSAD
Chapter 3. Hierarchical consensus architectures
SRT DHCA (sec.)
PRT DHCA (sec.)
10 0
10 −1
|df A | = 1 , |df D | = 14 , |df R | = 5
ADR ARD DAR DRA RAD RDA flat
DHCA variant
10 −1
(b) Serial real running time
|df A | = 1 , |df D | = 14 , |df R | = 5
ADR ARD DAR DRA RAD RDA flat
DHCA variant
(d) Parallel real running time
CSPA
EAC
HGPA
MCLA
ALSAD
KMSAD
SLSAD
CSPA
EAC
HGPA
MCLA
ALSAD
KMSAD
SLSAD
Figure 3.10: Estimated and real running times of the serial and parallel DHCA on the Zoo
data collection in the diversity scenario corresponding to a cluster ensemble of size l = 57.
sensus architecture as in the serial case. Moreover, notice that in this low diversity scenario,
hierarchical consensus architectures are, in general terms, slower than flat consensus.
Diversity scenario |df A| =10
Figure 3.11 presents the results obtained in the diversity scenario corresponding to the generation
of the cluster ensemble by the application of |dfA| = 10 clustering algorithms chosen
at random. In this case, there exists at least one serial DHCA variant that performs faster
than flat consensus —the only exception occurs when consensus are created by the EAC
consensus function (recall this also happened with RHCA, see section 3.2.4). As in the previous
diversity scenario, all the parallel DHCA variants yield pretty similar running times,
as opposed to what is observed in the serial case, where there exist significant execution
time differences between variants. Last, as regards the prediction of the computationally
optimal consensus architecture, notice that its performance is pretty accurate in both the
serial and parallel cases.
Diversity scenario |df A| =19
As the diversity level of the cluster ensemble increases, a shift in the computationally optimal
serial DHCA variant can be observed —see figure 3.12. Indeed, as figure 3.12(b) shows,
the ADR variant of DHCA becomes the least computationally expensive serial hierarchical
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