(deffacts data
  (vector a b c d e f g)
)

(defrule init
  (not (inverse $?))
  =>
  (assert (inverse))
)

(defrule inverse
  ?idx <- (vector ?x $?rest)
  ?idxi <- (inverse $?inv)
  =>
  (retract ?idx ?idxi)
  (assert (vector $?rest)
          (inverse ?x $?inv))
)

(defrule final
  ?a <- (vector)
  ?b <- (inverse $?ceva)
  =>
  (retract ?a ?b)
  (assert (vector $?ceva))
  (halt)
)