) ▁can ▁have ▁ ▁Rel ations ▁ ▁W ays ▁in ▁which ▁classes ▁and ▁individuals ▁can ▁be ▁related ▁to ▁one ▁another ▁ ▁Function ▁terms ▁ ▁Complex ▁structures ▁formed ▁from ▁certain ▁relations ▁that ▁can ▁be ▁used ▁in ▁place ▁of ▁an ▁individual ▁term ▁in ▁a ▁statement ▁ ▁Rest rict ions ▁ ▁Form ally ▁stated ▁descri ptions ▁of ▁what ▁must ▁be ▁true ▁in ▁order ▁for ▁some ▁assertion ▁to ▁be ▁accepted ▁as ▁input ▁ ▁R ules ▁ ▁Stat ements ▁in ▁the ▁form ▁of ▁an ▁if - then ▁( ante ced ent - con sequ ent ) ▁sentence ▁that ▁describe ▁the ▁logical ▁infer ences ▁that ▁can ▁be ▁drawn ▁from ▁an ▁assertion ▁in ▁a ▁particular ▁form ▁ ▁A xi oms ▁ ▁Assert ions ▁( including ▁rules ) ▁in ▁a ▁logical ▁form ▁that ▁together ▁compr ise ▁the ▁overall ▁theory ▁that ▁the ▁ont ology ▁describes ▁in ▁its ▁domain ▁of ▁application . ▁This ▁definition ▁diff ers ▁from ▁that ▁of ▁" axi oms " ▁in ▁gener ative ▁grammar ▁and ▁formal ▁logic . ▁ ▁In ▁those ▁discipl ines , ▁ax i oms ▁include ▁only ▁statements ▁assert ed ▁as ▁a ▁pri ori ▁knowledge . ▁ ▁As ▁used ▁here , ▁" axi oms " ▁also ▁include ▁the ▁theory ▁derived ▁from ▁ax iom atic ▁statements ▁ ▁Events ▁ ▁The ▁changing ▁of ▁attributes ▁or ▁relations ▁ ▁Ont ologies ▁are ▁commonly ▁encoded ▁using ▁ont ology ▁languages . ▁ ▁Types ▁ ▁Domain ▁ont ology ▁ ▁A ▁domain ▁ont ology ▁( or ▁domain - specific ▁ont ology ) ▁represents ▁concepts ▁which ▁belong ▁to ▁a ▁part ▁of ▁the ▁world , ▁such ▁as ▁bi