Combining Tolog and path expressions
"Dmitry" <[email protected]> Wed, 3 Mar 2004 21:47:42 -0500
| Newsgroups | gmane.text.xml.xtm.tmql |
|---|---|
| Message-ID | <000f01c40193$111fe620$7d01a8c0@dbn> |
I was recently discussing (as a puzzle) with Lars Marius possibility of integrating simple path expressions into tolog. I think that tolog is very good for querying associations. But I found that AsTMa, Toma and TMPath approaches are more attractive when it comes to querying topic properties. I think that it is possible to introduce simple path expressions into tolog without changing tolog semantics. It will help to create more compact queries. One of the discussed syntaxes: <topic variable>[<type expression>;<conditions with simple paths>] Example: $X[person; age<30,webpage like "..." | webpage like "... "], born-in($X:who,$Y:where), $Y[city] "age", "webpage" are simple paths related to topic $X, "person" is a type also constructs such as $X.age $X.webpage are allowed. Extended expressions can be re-written in regular tolog. "Existential" semantics of path expressions matches well tolog existential semantics. For example: $X[person; age <30] -> instanceOf($X,person),age($X,$V00001),$V00001<30 $X[person], $Y[person; age>$X.age] -> instanceOf($X,person),instanceOf($Y,person),age($Y,$V00003),age($X,$V00002),$V00003>$V00002 $X[perlHacker | pythonHacker] -> (instanceOf($X,perlHacker); instanceOf($X,pythonlHacker)) $X[whitePapper; webpage=$WP, $WP like "...."]-> instanceOf($X,whitePapper),webpage($X,$WP),like($WP,"....") Any thoughts? Thank you, Dmitry