ILOG OPL Development Studio Language Reference Manual

Constraints on groups of interval variablesThe main purpose of a group constraint is to encapsulate a group of interval variables intoone effective higher level interval.Three “interval grouping” constraints are available: span, alternative, and synchronize.Span constraint: The constraint span(a, {b 1 , .., b n }) states that the interval a spans over allpresent intervals from the set {b 1 , .., b n }. That is, interval a starts together with the first presentinterval from {b 1 , .., b n } and ends together with the last one.Alternative constraint:The constraint alternative(a, {b 1 , .., b n }) models an exclusivealternative between {b 1 , .., b n }. If interval a is present then exactly one of intervals {b 1 , ..,b n } is present and a starts and ends together with this chosen one.Synchronize constraint:The constraint synchronize(a, {b 1 , .., b n }) makes intervals b 1 . . . b nstart and end together with interval a (if a is present).Note that the alternative, span, and synchronize constraints cannot be used in meta-constraints.For syntax and examples, see the functions as described in the OPL Language Quick Reference.♦alternative♦span♦synchronize154I L O G O P L D E V E L O P M E N T S T U D I O L A N G U A G ER E F E R E N C E M A N U A L