Problems with Plans derived from source inversion rules
title-time(X, Y) :- dom(X), house-of-movies(X, Y)
title-actor (Y, X, Y) :- dom(X), house-of-movies(X, Y)
dom(Y) :- dom(X), house-of-movies(X, Y)
query(X,Y) :- title-time(X, Y)
title-time(X, Y) :- movie-hut(X, Y)
title-actor (Y, X, Y) :- movie-hut(X, Y)
dom(X) :- movie-hut(X, Y)
dom(Y) :- movie-hut(X, Y)
If both movie-hut and house-of-movies have same information:
- both sources are not necessary
- the recursion is not necessary
Every source that is remotely relevant to the query is made part of the plan
- Many of these sources may be overlapping