"Enter" rules

[id: hjjfuybdlbxeppif] fact(the state of a $x is defined by $y)
  => enter
  && entity(the $x)
  && entity(the state of the $x)
  && entity($y)
  && fact($y defines {the state of the $x})
  && ask(what is a good data structure for {the state of the $x}?)