A Harol

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Conference paper (4)

4 records found

On euclidean correction for non-euclidean dissimilarities

Conference paper (2008) - RPW Duin, EM Pekalska, A Harol, WJ Lee, H Bunke

Augmented embedding of dissimilarity data into (pseudo-)Euclidean spaces

Conference paper (2006) - A Harol, EM Pekalska, S Verzakov, RPW Duin

Pairwiseproximitiesdescribethepropertiesofobjectsintermsoftheirsimilarities.Byusingdi¿erentdistance-basedfunctionsonemayencodedi¿erentcharacteristicsofagivenproblem.However,tousetheframeworkofstatisticalpatternrecognitionsomevectorrepresentationshouldbeconstructed.Oneofthesimplestwaystodothatistode¿neanisometricembeddingtosomevectorspace.Inthiswork,wewillfocusonalinearembeddingintoa(pseudo-)Euclideanspace. Thisisusuallywellde¿nedfortrainingdata.Someinadequacy,however,appearswhenprojectingnewortestobjectsduetotheresultingprojectionerrors.Inthispaperweproposeanaugmentedembeddingalgorithmthatenlargesthedimensionalityofthespacesuchthattheresultingprojectionerrorvanishes.Ourpreliminaryresultsshowthatitmayleadtoabetterclassi¿cationaccuracy,especiallyfordatawithhighintrinsicdimensionality. ...

Non-Euclidean or non-metric measures can be informative

Conference paper (2006) - EM Pekalska, A Harol, RPW Duin, B Spillmann, H Bunke

StatisticallearningalgorithmsoftenrelyontheEuclideandistance.Inpractice,non-Euclideanornon-metricdissimilaritymeasuresmayarisewhencontours,spectraorshapesarecomparedbyeditdistancesorasaconsequenceofrobustobjectmatching[1,2].Itisanopenissuewhethersuchmeasuresareadvantageousforstatisticallearningorwhethertheyshouldbeconstrainedtoobeythemetricaxioms. Thek-nearestneighbor(NN)ruleiswidelyappliedtogeneraldissimilaritydataasthemostnaturalapproach.Alternativemethodsexistthatembedsuchdataintosuitablerepresentationspacesinwhichstatisticalclassi¿ersareconstructed[3].Inthispaper,weinvestigatetherelationbetweennon-Euclideanaspectsofdissimilaritydataandtheclassi¿cationperformanceofthedirectNNruleandsomeclassi¿erstrainedinrepresentationspaces.Thisisevaluatedonaparameterizedfamilyofeditdistances,inwhichparametervaluescontrolthestrengthofnon-Euclideanbehavior.Our¿ndingisthatthediscriminativepowerofthismeasureincreaseswithincreasingnon-Euclideanandnon-metricaspectsuntilacertainoptimumisreached.Theconclusionisthatstatisticalclassi¿ersperformwellandtheoptimalvaluesoftheparameterscharacterizeanon-Euclideanandsomewhatnon-metricmeasure ...

Pairwise selection of features and prototypes

Conference paper (2005) - EM Pekalska, A Harol, RPW Duin