“语义”而非“语法”，弱化对词法分析的技术要求和提升爬虫的效率

COMPPUTER SCIENCE AN OVERVIEW 11th Edition

Finally we should note that XML allows the development of new markuplanguages that differ from HTML in that they emphasize semantics rather thanappearance.  For  example,  with  HTML  the  ingredients  in  a  recipe  can  bemarked so that they appear as a list in which each ingredient is positioned on a separate  line.  But  if  we  used  semantic-oriented  tags,  ingredients  in  a  recipecould  be  marked  as  ingredients  (perhaps  using  the  tags  <ingredient> and </ingredient> ) rather than merely items in a list. The difference is subtlebut important. The semantic approach would allow search engines(Web sitesthat assist users in locating Web material pertaining to a subject of interest) toidentify  recipes  that  contain  or  do  not  contain  certain  ingredients,  whichwould be a substantial improvement over the current state of the art in whichonly recipes that do or do not contain certain words can be isolated. More pre-cisely,  if  semantic  tags  are  used,  a  search  engine  can  identify  recipes  forlasagna that do not contain spinach, whereas a similar search based merely onword  content  would  skip  over  a  recipe  that  started  with  the  statement  “Thislasagna does not contain spinach.” In turn, by using an Internet-wide standardfor  marking  documents  according  to  semantics  rather  than  appearance,  aWorld Wide SemanticWeb, rather than the World Wide SyntacticWeb we havetoday, would be created.