∀ (toForwardRuleInfo : Aesop.ForwardRuleInfo) (name : Aesop.RuleName) (term : Aesop.RuleTerm)
  (prio : Aesop.ForwardRulePriority),
  sizeOf { toForwardRuleInfo := toForwardRuleInfo, name := name, term := term, prio := prio } =
    1 + sizeOf toForwardRuleInfo + sizeOf name + sizeOf term + sizeOf prio