Infinite LengthImpractical to store and use all historical dataRequires infinitestorageAnd running timeLATETOO
Impractical to store and use all historical data Requires infinite storage And running time Infinite Length
Concept-DriftCurrent hyperplanePrevious hyperplaneAdata chunkNegativeinstanceInstancesvictimofconcept-driftPositive instance
Concept-Drift Negative instance Positive instance A data chunk Current hyperplane Previous hyperplane Instances victim of concept-drift
Concept-EvolutionNovel classyyDCXXXXXXXXXXXXXXXXYiCY1XXXXXKXXXXXXXXXXXXXXXXXXAAXXXXV2Y2X1XXClassificationrules:Rl.if (x >X, and y <y2) or (x<x, andy <y.) then class = +R2.if (x >×, and y ≥y2) or (× < ×, and y ≥yi) then class = Existingclassificationmodels misclassify novel class instances
Concept-Evolution X X X X X X X X X X XX X X X X X XX X X X X X X X X X X X X X X X XX X X X X X X X X X X X Novel class y x1 y1 y2 x ++++ ++ ++ + + ++ + +++ ++ + ++ + + + ++ + +++++ ++++ +++ + ++ + + ++ ++ + - - - - - - - - - - - - + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Classification rules: R1. if (x > x1 and y < y2 ) or (x < x1 and y < y1 ) then class = + R2. if (x > x1 and y > y2) or (x < x1 and y > y1 ) then class = - Existing classification models misclassify novel class instances A C D B y x1 y1 y2 x ++++ ++ ++ + + ++ + +++ ++ + ++ + + + ++ + +++++ ++++ +++ + ++ + + ++ ++ + - - - - - - - - - - - - + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - A D C B
Why newfeatures evolvingInfinitedatastreamNormally, global feature set is unknownNewfeaturesmayappearConcept driftAs conceptdrifting,newfeatures may appearConceptevolutionNewtypeof class normallyholdsnewsetof featuresDifferent chunks mayhavedifferentfeaturesets
Why new features evolving Infinite data stream Normally, global feature set is unknown New features may appear Concept drift As concept drifting, new features may appear Concept evolution New type of class normally holds new set of features Different chunks may have different feature sets
Dynamic Featuresjthchunkandi+/stchunkandmodelshavedifferentfeaturesetsrunway, clear,runway, climbrampFeature Setith chunki+ [st chunkrunway, ground,rampFeatureExtraction&SelectionClassification&CurrentFeature SpaceNovelClassDetectionmodelConversionTrainingNewModelExisting classification models need complete fixed features and apply to all thechunks. Global features are difficult to predict. One solution is using all Englishwordsandgeneratevector.Dimension of the vector will betoo high
Dynamic Features Feature Extraction & Selection i + 1st i chunk th chunk Existing classification models need complete fixed features and apply to all the chunks. Global features are difficult to predict. One solution is using all English words and generate vector.Dimension of the vector will be too high. Current model Training New Model Feature Space Conversion Classification & Novel Class Detection runway, climb runway, clear, ramp runway, ground, ramp i th chunk and i + 1st chunk and models have different feature sets Feature Set