code: public void getOverlapping(Wikipedia pWiki, CategoryGraph catGraph) throws WikiApiException {
          double startTime = System.currentTimeMillis();
  
          int articlesWithOverlappingCategories = getArticlesWithOverlappingCategories(pWiki, catGraph);
          double overlappingCategoriesRatio = (double) articlesWithOverlappingCategories / (double) pWiki.getMetaData().getNumberOfPages();
          logger.info(articlesWithOverlappingCategories + " - " + pWiki.getMetaData().getNumberOfPages() + " - " + overlappingCategoriesRatio);
  
          double endTime = (System.currentTimeMillis() - startTime) / 1000.0;
          logger.debug("{} ms", endTime);
      }
docs: Articles in wikipedia may be tagged with multiple categories.
  It may be interesting to know how many articles have at least one category in common.
  Such articles would have a very high semantic relatedness even if they share a quite secondary category.
  @param pWiki The wikipedia object.
  @param catGraph The category graph.
  @throws WikiApiException