JaCoP.constraints.netflow.simplex
Class Arc

java.lang.Object
  JaCoP.constraints.netflow.simplex.Arc

public final class Arc
extends java.lang.Object

A directed, residual arc in the graph.

Version:

3.1

Author:

Robin Steiger and Radoslaw Szymanek

Field Summary

int	capacity The unused (i.e.
ArcCompanion	companion The arc companion for constraint API.
int	cost The cost of the Arc cost
boolean	forward whether this arc is a forward arc or a residual arc
Node	head The head of the arc (where the arc points to).
int	index Index in lower arcs array
Arc	sister The flow of an arc is the residual capacity of its sister arc.

Constructor Summary

Arc(Node tail, Node head)
Special constructor to create artificial arcs.

Arc(Node tail, Node head, int cost, int lowerCapacity, int upperCapacity)
General constructor to create arcs.

Method Summary

void	addFlow(int delta)
void	clear() Clears an artificial arc
ArcCompanion	getCompanion()
boolean	hasCompanion()
boolean	isInCut(boolean forward)
long	longCost()
java.lang.String	name()
int	reducedCost() Computes the cost of this arc considering node potentials.
void	set(int newCost, int newCapacity) Initializes an artificial arc
Node	tail()
java.lang.String	toFlow()
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

head

public final Node head

The head of the arc (where the arc points to). The head of an arc is the tail of its sister arc.

cost

public int cost

The cost of the Arc cost

capacity

public int capacity

The unused (i.e. residual) capacity of the arc

sister

public final Arc sister

The flow of an arc is the residual capacity of its sister arc.

index

public int index

Index in lower arcs array

companion

public ArcCompanion companion

The arc companion for constraint API. Only forward arcs have a companion, residual arcs do not.

forward

public boolean forward

whether this arc is a forward arc or a residual arc

Constructor Detail

Arc

public Arc(Node tail,
           Node head)

Special constructor to create artificial arcs. Should NOT be used in a model. Models should use (or subclass) a NetworkBuilder instead. A NetworkBuilder provides various addArc methods to create arcs more conveniently.

Parameters:

tail - tail of the arc

head - head of the arc

Arc

public Arc(Node tail,
           Node head,
           int cost,
           int lowerCapacity,
           int upperCapacity)

General constructor to create arcs. Models should consider to use (or subclass) a NetworkBuilder instead. A NetworkBuilder provides various addArc methods to create arcs more conveniently.

Parameters:

tail - tail of the arc

head - head of the arc

cost - cost-per-unit of the arc

lowerCapacity - lower capacity of the arc

upperCapacity - upper capacity of the arc

Method Detail

reducedCost

public int reducedCost()

Computes the cost of this arc considering node potentials.

Returns:

the reduced cost

addFlow

public void addFlow(int delta)

tail

public Node tail()

isInCut

public boolean isInCut(boolean forward)

set

public void set(int newCost,
                int newCapacity)

Initializes an artificial arc

Parameters:

newCost -

newCapacity -

clear

public void clear()

Clears an artificial arc

longCost

public long longCost()

Returns:

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toFlow

public java.lang.String toFlow()

hasCompanion

public boolean hasCompanion()

getCompanion

public ArcCompanion getCompanion()

name

public java.lang.String name()