Availability:
:- use_module(library(clpfd)).
cumulative(+Tasks,
+Options)task(S_i, D_i, E_i, C_i, T_i). S_i denotes
the start time, D_i the positive duration, E_i the end time, C_i the
non-negative resource consumption, and T_i the task identifier. Each of
these arguments must be a finite domain variable with bounded domain, or
an integer. The constraint holds iff at each time slot during the start
and end of each task, the total resource consumption of all tasks
running at that time does not exceed the global resource limit. Options
is a list of options. Currently, the only supported option is:
- limit(L)
- The integer L is the global resource limit. Default is 1.
For example, given the following predicate that relates three tasks of durations 2 and 3 to a list containing their starting times:
tasks_starts(Tasks, [S1,S2,S3]) :-
Tasks = [task(S1,3,_,1,_),
task(S2,2,_,1,_),
task(S3,2,_,1,_)].
We can use cumulative/2 as follows, and obtain a schedule:
?- tasks_starts(Tasks, Starts), Starts ins 0..10, cumulative(Tasks, [limit(2)]), label(Starts). Tasks = [task(0, 3, 3, 1, _G36), task(0, 2, 2, 1, _G45), ...], Starts = [0, 0, 2] .