@prefix log: <http://www.w3.org/2000/10/swap/log#> .
@prefix dpo: <http://www.daml.org/2001/03/daml+oil#> .
@prefix ont: <http://www.daml.org/2001/03/daml-ont#> .
@prefix : <#> .
@prefix date: <http://www.mnot.net/2002/01/11/date#> .
@prefix math: <http://www.w3.org/2000/10/swap/math#> .
@prefix x: <http://www.mnot.net/test#> .


:Charlie :birthday "2001-12-09" .
:Mark :birthday "1971-11-30" .

this log:forAll :x, :y, :z, :a .
  { :x :birthday :z .
    :z date:inSeconds :a } 
  log:implies
  { :x :birthdate :a } .


this log:forAll :x, :y, :z, :a, :b, :c .
  { :x :birthdate :z .
    :a :birthdate :c .
    :z math:lessThan :c .
  }
  log:implies
  { :x :olderthan :a } .

:olderthan dpo:inverseOf :youngerthan