Herbrand Terms

• Our last example will be Herbrand terms
• Herbrand terms are defined as:
  • A variable is a Herbrand term
  • A constant is a Herbrand term
  • A functor $f$ with arity $n$ applied to $n$ terms is a Herbrand term: $f(t_1, t_2,\ldots t_n)$
• Herbrand terms represent trees:
  • Variables are open leaves
  • Constants are fully instantiated leaves
  • Function symbols are nodes
• Example: $f(a, X, g(Y, t))$ represents the tree
  figure=clp_seminar_figs/tree.eps,width=0.4