<schema xmlns="http://purl.oclc.org/dsdl/schematron">
  <ns uri="http://www.schematron.info/arche" prefix="ark"/>
  <pattern>                                                   (1)
    <rule context="ark:animal[@sex='male']">                  (1a)
      <report test="number(ark:age) &gt; number(//ark:maxReproductionAge/ark:animal_species[ark:name=current()/ark:species]/ark:male)"> (1b)
      The male is too old, Noah! It is probably no longer able to reproduce.
      You have to enforce the natural selection.</report>
    </rule>
    <rule context="ark:animal[@sex='female']">                (1a)
      <report test="number(ark:age) &gt; number(//ark:maxReproductionAge/ark:animal_species[ark:name=current()/ark:species]/ark:female)"> (1b)
      The female is too old, Noah! It is probably no longer able to reproduce.
      You have to enforce the natural selection.</report>
    </rule>
  </pattern>
 
  <pattern>
    <rule context="ark:loadingCapacity">                       (2)
      <report test=". &lt; sum(//ark:weight)">                 (2a)
      Noah, there are too many animals on board. 
      The load exceeds the loading capacity of your Ark.</report>
    </rule>
  </pattern>
 
  <pattern>                                                    (3)
    <rule context="ark:animal[@carnivore='yes']">
      <report test="parent::*/ark:animal[@carnivore='no']">
      There are carnivores and herbivores in one accommodation. 
      The animals are not a food source!</report>
      <report test="parent::*/ark:animal/ark:weight &lt; (ark:weight div 2)">
      Noah, this carnivore is too strong (heavy) for its roommate.
      The carnivore could use it as a food source.</report>
    </rule>
    <rule context="ark:animal">
      <report test="parent::*/ark:animal/ark:weight &lt; (ark:weight div 10)">
      Noah, the animal is too heavy for its rommates! 
      It could trample down one of them.</report>
    </rule>
  </pattern>
 
  <pattern>
    <rule context="ark:animal">                                                             (4)
      <report test="count(//ark:animal[ark:species=current()/ark:species]) &gt; 2">         (4a)
      There are more than two animals of this species on the Ark.</report>
      <report test="count(parent::*/ark:animal[ark:species=current()/ark:species]) &lt; 2"> (4b)
      There are less than two animals of this species in this accommodation.
      </report>
      <assert test="count(parent::*/ark:animal[ark:species=current()/ark:species][@sex='male'])=1"> (4c)
      A pair must always consist of one male and one female.
      </assert>
    </rule>
  </pattern>
 
  <pattern>
    <rule context="ark:room">                                       (5)
      <report test="count(ark:animal) &gt; 6">
      Noah, if you accommodate too many animals in the same room, it could have a 
      negative effect on the room community! You should not accommodate 
      more than 6 animals in one room.
      </report>
    </rule>
  </pattern>
</schema>