dteval(Obj,DT,Cl)is true if object Obj is classified by decision tree DT as having value Cl.
dteval(Ex,V,V) <- value(V). dteval(Ex,if(A=V,T1,T2),C) <- prop(Ex,A,V) & dteval(Ex,T1,C). dteval(Ex,if(A=V,T1,T2),C) <- prop(Ex,C,W) & W \= V & dteval(Ex,T2,C).