code: def _f_lcs(llcs, m, n):
      """
      Computes the LCS-based F-measure score
      Source: http://research.microsoft.com/en-us/um/people/cyl/download/papers/
      rouge-working-note-v1.3.1.pdf
  
      :param llcs: Length of LCS
      :param m: number of words in reference summary
      :param n: number of words in candidate summary
      :returns float: LCS-based F-measure score
      """
      r_lcs = llcs / m
      p_lcs = llcs / n
      beta = p_lcs / r_lcs
      num = (1 + (beta**2)) * r_lcs * p_lcs
      denom = r_lcs + ((beta**2) * p_lcs)
      return num / denom
  
file_path: sumy/sumy/evaluation/rouge.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  from ..models.dom import Sentence
label_desc: Use image node_id 11 for calling a global function with example usage: _f_lcs(llcs, m, n) and returns: unknown