: a stream of examples
: a set of symbolic attributes
: heuristic evaluation function for node splitting
: one minus desired probability of choosing the correct attribute at any given node.
: number of samples between estimation of growth
: sorted list of Hoeffding bound values
: total number of values in
: new Hoeffding Bound value seen at the node
: adaptive threshold
: subset of
: 5% of examples in . Threshold for checking the eligibility of a node to be part of HT
Size of
 A decision tree HT
Procedure EnhancedVFDT(, , , , )
A stream of examples arrives
  IF (), THEN TreeInitialization(S, X)
    Get an Initialized HT with a single root node
  IF (), THEN NewStreamSample(S, X)
  Label with the majority class among the samples seen so far at
  Let be the number of samples seen at
  IF the samples seen so far at are not all of the same class and
    Compute for each attribute using
    PrunedMean = AccuracyEVFDT(, , , )
    Let be the attribute with highest and be the attribute with second-highest
    Compute using (1)
    IF ( or PrunedMean) and , THEN split as a branch
      FOR each branch of split
       Add a new leaf and let
       Let be the obtained by predicting the most frequent class at
       FOR each class and each value of each attribute
       Let .
  ELSE  Pruning(, , , , HT)
Return HT
Algorithm 1: EVFDT procedure: enhanced EVFDT.