anchor.diff:  
   After that, we evaluate Performance as:
   
  -Performance = latexmath:[$\left\{
  +Performance = latexmath:[\left\{
       \begin{array}{ll}
  -        \multicolumn{2}{l}{100.0 * (1.0 - {\rm Execution~Time})} \\
  -          & {\rm if~Execution~Time~is~less~than~1~second}  \\
  +        100.0 * (1.0 - {\rm Execution~Time}) & {\rm if~Execution~Time~is~less~than~1~second} \\
           0 & {\rm Otherwise}
       \end{array}
  -    \right.$]
  +    \right.]
  
positive.code: 
  At last, we evaluate Usefulness Score as follows:
  
  latexmath:[$\begin{array}{lll}
    {\rm Usefulness} & = & 30.0 * {\rm Metadata~Score} \\
                     & + & 40.0 * f10({\rm Vocabulary~Score}) \\
                     & + & 30.0 * {\rm Ontology~Score}
    \end{array}$]
  
  where
  
  latexmath:[$f10(x) = \left\{
      \begin{array}{ll}
        10 & {\rm if}~x>10 \\
        x  & {\rm Otherwise}
      \end{array}
    \right.$]
  
  [[validity]]
  === 2.5 Validity
  
negative.code: We evaluate Metadata score as follows:
  +
  Metadata Score =
  latexmath:[\frac{\displaystyle \sum_{graphs}^{g}(c(g) + l(g) + p(g) + d(g))}{N}]
  
  where
  
  latexmath:[N] = Number of Graphs
  
  latexmath:[c(g) = \left\{
          \begin{array}{ll}
              0   & {\rm if~g~does~not~contains~any~classes} \\
              25  & {\rm if~g~contains~more~than~zero~classes}
          \end{array}
          \right.]
  
  latexmath:[l(g) = \left\{
          \begin{array}{ll}
              0   & {\rm if~g~does~not~contains~any~labels} \\
              25  & {\rm if~g~contains~more~than~zero~labels}
          \end{array}
          \right.]
  
  latexmath:[p(g) = \left\{
          \begin{array}{ll}
              0   & {\rm if~g~does~not~contains~any~properties} \\
              25  & {\rm if~g~contains~more~than~zero~properties}
          \end{array}
          \right.]
  
  latexmath:[d(g) = \left\{
          \begin{array}{ll}
              0   & {\rm if~g~does~not~contains~any~datatypes} \\
              25  & {\rm if~g~contains~more~than~zero~datatypes}
          \end{array}
          \right.]
  * Vocabulary Score
  +
  Vocabulary Score, which is calculated based on metadata, represents how
  