Example

X: Each instance is a pair of objects describe by: Type, Color, Volume, Owner, Material, Density, and On.
H: Each one is a set of Horn clauses.
Target Concept: SafeToStack(x,y)
D: One example looks like:
SafeToStack(o1,o2),On(o1,o2), Type(o1,Box), Type(o2, endtable), Color(o1,red), Color(o2,blue), Volume(o1, 2), Owner(o1, Fred), Owner(o2, Louis), Density(o1, 0.3), Material(o1, Cardboard), Material(o2, Wood)
B: Domain Theory

SafeToStack(x,y) ← ¬Fragile(y)
SafeToStack(x,y) ← Lighter(x,y)
Lighter(x,y) ← Weight(x,wx) ∧ Weight(y,wy) ∧ LessThan(wx,wy)
Weight(x,w) ← Volume(x,v) ∧ Density(x,d) ∧ Equal(w,times(v,d))
Weight(x,5) ← Type(x, endtable)
Fragile(x) ← Material(x,Glass)
Find h that is consistent with training examples and domain theory.