如何在Ruby中实现CYK解析算法？

def cyk_parse(grammar, sentence)
  n = sentence.length
  matrix = Array.new(n) { Array.new(n) { [] } }

  # Step 1: Fill the matrix with terminals
  (0...n).each do |i|
    matrix[i][i] = grammar.select { |rule| rule[1] == sentence[i] }.map { |rule| rule[0] }
  end

  # Step 2: Apply grammar rules
  (2..n).each do |l|
    (0..n-l).each do |i|
      j = i + l - 1
      (i..j-1).each do |k|
        matrix[i][j] += grammar.select { |rule| rule[2] == [matrix[i][k], matrix[k+1][j]] }.map { |rule| rule[0] }
      end
    end
  end

  # Step 3: Check if the start symbol is in the top right cell
  matrix[0][n-1].include?(grammar[0][0])
end

# Define the grammar rules
grammar = [
  [:S, 'NP', 'VP'],
  [:NP, 'Det', 'N'],
  [:VP, 'V', 'NP'],
  ['Det', 'the'],
  ['N', 'cat'],
  ['V', 'chased']
]

# Define the sentence to parse
sentence = ['the', 'cat', 'chased']

# Perform CYK parsing
if cyk_parse(grammar, sentence)
  puts "The sentence is valid."
else
  puts "The sentence is not valid."
end