xml - XPath count() function

Question

Suppose I have an XML tree as below:

proceedings
   -name
   -contents
      -article
         -author
         -title
         -pages

How can I identify any title that has only one author? And the number of articles that have more than three author using XPath?

Answer 1

Title with one author:

/proceedings/contents/article[count(author)=1]/title

Number of articles with more than three authors:

count(/proceedings/contents/article[count(author)>3])