A training instance in their case was constituted by an input analogy, and the corresponding output equation along with one solution produced.
for the translation of the input form u, any pair ([x : y :: z : u], [x' : y' :: z' : c]), with x' , y' , and z' in τ (x' ), τ (y' ), and τ (z' ) respectively, and c a candidate translation would be considered for classification.