func dinesman(problem) {
  var lines = problem.split('.')
  var names = lines.first.scan(/\b[A-Z]\w*/)
  var re_names = Regex(names.join('|'))
 
  # Later on, search for these keywords (the word "not" is handled separately).
  var words = %w(first second third fourth fifth sixth seventh eighth ninth tenth
                 bottom top higher lower adjacent)
  var re_keywords = Regex(words.join('|'))
 
  # Build an array of lambda's
  var predicates = lines.first(-1).last(-1).map{ |line|
    var keywords = line.scan(re_keywords)
    var (name1, name2) = line.scan(re_names)...
 
    keywords.map{ |keyword|
      var l = do {
        given(keyword) {
            when ("bottom")   { ->(c) { c.first == name1 } }
            when ("top")      { ->(c) { c.last == name1 } }
            when ("higher")   { ->(c) { c.index(name1) > c.index(name2) } }
            when ("lower")    { ->(c) { c.index(name1) < c.index(name2) } }
            when ("adjacent") { ->(c) { c.index(name1) - c.index(name2) -> abs == 1 } }
            default           { ->(c) { c[words.index(keyword)] == name1 } }
        }
      }
      line ~~ /\bnot\b/ ? func(c) { l(c) -> not } : l;  # handle "not"
    }
  }.flat
 
  names.permutations { |*candidate|
    predicates.all { |predicate| predicate(candidate) } && return candidate
  }
}