%%%  ________________________
%%% |                        |
%%% |________________________|
%%% |      ________________  |
%%% |     | x3 x1 x2       | |
%%% | __  |________________| |
%%% |   | | book(x3)       | |
%%% |     | borrow(x1)     | |
%%% |     | today(x2)      | |
%%% |     | event(x1)      | |
%%% |     | patient(x1,x3) | |
%%% |     | rel(x1,x2)     | |
%%% |     |________________| |
%%% |________________________|