code: public Category getLCS(int categoryPageId1, int categoryPageId2) throws WikiApiException {
      	int lcsid = getLCSId(categoryPageId1, categoryPageId2);
      	return lcsid>-1?wiki.getCategory(getLCSId(categoryPageId1, categoryPageId2)):null;
      }
docs: Gets the lowest common subsumer (LCS) of two nodes.
  The LCS of two nodes is first node on the path to the root, that has both nodes as sons.
  Nodes that are not in the same connected component as the root node are defined to have no LCS.
  @param categoryPageId1 The pageid of the first category node.
  @param categoryPageId2 The pageid of the second category node.
  @return The lowest common subsumer of the two nodes, or null if there is no LCS.