
disjunctive(+StartTimes, +Durations)

   Constrain the tasks with specified start times and durations to not overlap in time.

Arguments
   StartTimes          Collection of N start times for tasks (domain variables or integers)
   Durations           Collection of N durations for tasks (non-negative domain variables or integers)

Type
   library(gfd)

Description

    A disjunctive scheduling constraint. StartTimes and Durations are
    collections (a la collection_to_list/2) of equal size N of integer
    variables or integers. Durations must be non-negative.
 
    The declarative meaning is that the N tasks with the given start 
    times and durations do not overlap at any point in time, i.e. for
    any pairs of tasks X and Y, the following holds:

        (Xstart + Xduration =
    Note that the constraint is implemented by different Gecode propagators,
    depending on if Durations contains domain variables or not. If
    Durations does have domain variables, the Gecode propagator requires
    an extra End domain variable specifying the end time, and a constraint 
        
      End #= Start + Duration  

    for each task. These are posted as part of the constraint (the End 
    variables are not accessible by the user).

    Any input variables which are not already domain variables will be
    converted into domain variables with default bounds.

    This constraint is also known as disjunctive in the global constraint
    catalog, but in the catalog, tasks with zero duration are allowed
    to overlap with other tasks. The constraint is implemented using 
    Gecode's unary constraint (with extra constraints on task end times if 
    any task duration is a domain variable).



Examples
   
[eclipse 2]: disjunctive([1,7,4],[3,2,1]).    % succeed

[eclipse 3]: disjunctive([1,7,3], [3,2,1]).   % fail

[eclipse 4]: disjunctive([1,4,7,4],[3,0,2,1]). % succeed 

[eclipse 5]: disjunctive([1,2,7,4],[3,0,2,1]). % fail 


[eclipse 5]: [S2,S4]::[1..9], disjunctive([1,S2,7,S4], [3,1,2,1]).

S2 = S2{[4 .. 9]}
S4 = S4{[4 .. 9]}



See Also
   ic_edge_finder : disjunctive / 2, ic_edge_finder3 : disjunctive / 2, edge_finder : disjunctive / 2, edge_finder3 : disjunctive / 2, disjunctive_optional / 3, cumulative / 4, cumulatives / 5, eclipse_6 : collection_to_list / 2, lists : collection_to_list / 2
