Labels:text | screenshot | font | number | display | line | parallel OCR: 11 - Unification Page 7 When two structures with variables are unified with each other, the variables take on values which make the two structures the same. Note that a structure bound to a variable can itself contain variables. ??- X = a(b, c). X = a(b, c) -> yes ??- a(b,X) = a(b, c(d,e) ). X = c(d, e) -> yes ??- a(b, X) = a(b,c(Y,e)). X = c(_2F3D, e) Y = _ 2F3D -> Legal Keys: : (ask for more) {- (accept answer) Figure 1. One frame of APT's unification chapter