how propositional logic can be used in Boolean search? Give detail answer with an example of web page searching.

Computerized search engines can do more. Let us assume that they also can match, completely or approximately, on any pre-coordinated headings in the search system as a whole (the software will use → thesauri and similar devices to be able to do this). Then the French cooking heading mentioned earlier might not even exist as a heading until someone somewhere types into a search engine a string like ‘French and cooking’. Once search creates that heading, it may disappear immediately, it may be cached for one minute, one hour, or for one day, or it may be added sui generis as a heading in its own right. If thousands of Users search for ‘French and cooking’ likely the heading French cooking will be added as a pre-coordinate pre-emptively indexed entry (and cease to be processed in a post-coordinated fashion).