Relation ITEM

• Defined in theory: Kif-lists
• Source code: kif-lists.lisp

Slots on this relation:

Documentation:

The sentence {tt (item $tau_1$ $tau_2$)} is true if and only if the object denoted by $tau_2$ is a non-empty list and the object denoted by $tau_1$ is either the first item of that list or an item in the rest of the list.

Instance-Of: Relation

Arity: 2

Range: List

Other Related Axioms:

(=> (Item $X $Y) (List $Y))

(=> (Item ?X ?List)
    (And (Not (Null ?List))
         (Or (= ?X (First ?List)) (Item ?X (Rest ?List)))))

(<- (Adjoin ?X ?List) (If (Item ?X ?List) ?List (Cons ?X ?List)))