Module org.maxicp

Package org.maxicp.cp.engine.constraints.scheduling

Class IsEndBeforeStartWithTransition

java.lang.Object

org.maxicp.cp.engine.core.AbstractCPConstraint

org.maxicp.cp.engine.constraints.scheduling.IsEndBeforeStartWithTransition

All Implemented Interfaces:

CPConstraint, ConcreteConstraint<ConcreteCPModel>

public class IsEndBeforeStartWithTransition
extends AbstractCPConstraint

Reified temporal ordering constraint with transition times.

Links a boolean variable isBefore to the temporal ordering of two intervals with minimum transition times:

• isBefore = true ⇔ end(a) + transitionAB <= start(b) (interval a finishes before b starts, with at least transitionAB in between)
• isBefore = false ⇔ end(b) + transitionBA <= start(a) (interval b finishes before a starts, with at least transitionBA in between)

The constraint propagates in three directions:

1. Boolean → temporal: when isBefore is fixed, enforce the corresponding start/end bounds with transition times.
2. Temporal → boolean: when the temporal gap between the intervals is large enough, fix isBefore to the entailed ordering.
3. Infeasibility detection: when one ordering is impossible (the earliest end of one interval plus the transition exceeds the latest start of the other), fix isBefore to the only feasible ordering.

This constraint is a building block of NoOverlapWithPosition and replaces the more generically named NoOverlapBinaryWithTransitionTime in that context, making the reified semantics explicit.

Author:

Pierre Schaus

Constructor Summary

Constructors

Constructor	Description
IsEndBeforeStartWithTransition(CPBoolVar isBefore, CPIntervalVar a, CPIntervalVar b, int transitionAB, int transitionBA)	Creates a reified temporal ordering constraint with transition times.

Method Summary

Modifier and Type	Method	Description
void	post()	Initializes the constraint when it is posted to the solver.
void	propagate()	Propagates the constraint.

Methods inherited from class org.maxicp.cp.engine.core.AbstractCPConstraint

getSolver, isActive, isScheduled, priority, registerDelta, setActive, setScheduled, updateDeltas

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

IsEndBeforeStartWithTransition

public IsEndBeforeStartWithTransition(CPBoolVar isBefore,
 CPIntervalVar a,
 CPIntervalVar b,
 int transitionAB,
 int transitionBA)

Creates a reified temporal ordering constraint with transition times.

Parameters:

isBefore - boolean variable: true iff a ends before b starts (with transitionAB gap)

a - first interval

b - second interval

transitionAB - minimum gap between end(a) and start(b) when a precedes b

transitionBA - minimum gap between end(b) and start(a) when b precedes a

Method Details

post

public void post()

Description copied from interface: CPConstraint

Initializes the constraint when it is posted to the solver.

Specified by:

post in interface CPConstraint

Overrides:

post in class AbstractCPConstraint

propagate

public void propagate()

Description copied from interface: CPConstraint

Propagates the constraint.

Specified by:

propagate in interface CPConstraint

Overrides:

propagate in class AbstractCPConstraint