Data structures [Script]

[id: ghibojprnbvcwjos]
  input(what is a good data structure for a $x?)
  && 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})
  && input(what is a good data structure for {the state of the $x}?)

[id: iwguefzfgabfabvs]
  entity(the $faces of $y) => entity($y)