Shaving (JaCoP 4.9.0 API)

java.lang.Object
- org.jacop.search.Shaving<T>

All Implemented Interfaces:

ConsistencyListener, ExitChildListener<T>
```
public class Shaving<T extends IntVar>
extends Object
implements ExitChildListener<T>, ConsistencyListener
```
Defines functionality of shaving. Plugin in this object to search to change your depth first search to a search with shaving capabilities.
Shaving
Each search level stores the variable value pairs which were shaved at a given level.
Shaving speculation.
The right child is using all the shavable pairs from the subtree rooted at the sibling of the current search node. If shaving fails then it is recorded in non shavable.
Not-shavable speculation
Every time a variable value pair is being schedule for shavability check then it is checked if that pair was not already checked for shavability before with a negative results. If so, then check is not performed but also entry in not-shavable is removed.
If variable value pair proofs to be not shavable then this variable value pair is recorded into Not-shavable speculation.
Quick shave - upon exiting any subtree the variable value pair which was choosen at the root of that subtree is recorded as shavable variable value pair.

Version:

4.9

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

Fields
Modifier and Type	Field and Description
`int`	`failures` It stores number of failed shaving attempts.
`boolean`	`onlyFailedConstraint` It specifies if only the last failed constraint is allowed to suggest shaving values.
`boolean`	`onlyIntVarsOfFailedConstraint` It specifies if only variables in the scope of the last failed constraint are allowed to be used in shaving attempts.
`boolean`	`quickShave` It specifies if the quickShave approach should be also used.
`int`	`successes` It stores number of successful shaving attempts.
`HashSet<IntVar>`	`varsOfFailedConstraint` It stores the variables of the last failed constraints.

Constructor Summary

Constructors
Constructor and Description

Shaving()

Constructors
Constructor and Description
`Shaving()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addShavingConstraint(Constraint c)` It adds shaving constraint to the list of constraints guiding shaving.
`boolean`	`executeAfterConsistency(boolean consistent)` It is executed right after consistency of the current search node.
`boolean`	`leftChild(IntVar var, int value, boolean status)` It is executed after exiting the left child.
`boolean`	`leftChild(PrimitiveConstraint choice, boolean status)` It is executed after exiting the left child.
`void`	`rightChild(IntVar var, int value, boolean status)` It is executed after exiting the right child.
`void`	`rightChild(PrimitiveConstraint choice, boolean status)` It is executed after exiting the right child.
`void`	`setChildrenListeners(ConsistencyListener child)` Setting one child listener.
`void`	`setChildrenListeners(ConsistencyListener[] children)` Each of the child listeners will be called and the return code from them will be combined (taken into account) by a parent).
`void`	`setChildrenListeners(ExitChildListener child)` It adds one child listener.
`void`	`setChildrenListeners(ExitChildListener[] children)` It sets the children listeners for the current listener.
`void`	`setStore(Store store)` It specifies the constraint store in which context the shaving will take place.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - onlyFailedConstraint
```
public boolean onlyFailedConstraint
```
    It specifies if only the last failed constraint is allowed to suggest shaving values.
  - onlyIntVarsOfFailedConstraint
```
public boolean onlyIntVarsOfFailedConstraint
```
    It specifies if only variables in the scope of the last failed constraint are allowed to be used in shaving attempts.
  - varsOfFailedConstraint
```
public HashSet<IntVar> varsOfFailedConstraint
```
    It stores the variables of the last failed constraints.
  - quickShave
```
public boolean quickShave
```
    It specifies if the quickShave approach should be also used. Quickshave uses variable-value pairs which lead to wrong decisions as shaving values higher in the search tree (until the first time shaving attempt for this value fails).
  - successes
```
public int successes
```
    It stores number of successful shaving attempts.
  - failures
```
public int failures
```
    It stores number of failed shaving attempts.
- Constructor Detail
  - Shaving
```
public Shaving()
```
- Method Detail
  - leftChild
```
public boolean leftChild(IntVar var,
                         int value,
                         boolean status)
```
    Description copied from interface: ExitChildListener
    
    It is executed after exiting the left child.
    
    Specified by:
    
    leftChild in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    var - variable used in the choice point.
    
    value - value used in the choice point.
    
    status - true if the solution was found in the child subtree, false otherwise.
    
    Returns:
    
    true if the search should continue undisturbed, false if it should exit the current node with false
  - leftChild
```
public boolean leftChild(PrimitiveConstraint choice,
                         boolean status)
```
    Description copied from interface: ExitChildListener
    
    It is executed after exiting the left child.
    
    Specified by:
    
    leftChild in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    choice - primitive constraint used as the base of the choice point.
    
    status - true if the solution was found in the child subtree, false otherwise.
    
    Returns:
    
    true if the search should continue undisturbed to the right node, false if it should exit the current node with false
  - rightChild
```
public void rightChild(IntVar var,
                       int value,
                       boolean status)
```
    Description copied from interface: ExitChildListener
    
    It is executed after exiting the right child.
    
    Specified by:
    
    rightChild in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    var - variable used in the choice point.
    
    value - value used in the choice point.
    
    status - true if the solution was found in the child subtree, false otherwise. exit the current node with false
  - rightChild
```
public void rightChild(PrimitiveConstraint choice,
                       boolean status)
```
    Description copied from interface: ExitChildListener
    
    It is executed after exiting the right child.
    
    Specified by:
    
    rightChild in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    choice - primitive constraint used as the base of the choice point.
    
    status - true if the solution was found in the child subtree, false otherwise. exit the current node with false
  - setChildrenListeners
```
public void setChildrenListeners(ConsistencyListener[] children)
```
    Description copied from interface: ConsistencyListener
    
    Each of the child listeners will be called and the return code from them will be combined (taken into account) by a parent).
    
    Specified by:
    
    setChildrenListeners in interface ConsistencyListener
    
    Parameters:
    
    children - the children listeners attached to this listener.
  - setChildrenListeners
```
public void setChildrenListeners(ExitChildListener[] children)
```
    Description copied from interface: ExitChildListener
    
    It sets the children listeners for the current listener.
    
    Specified by:
    
    setChildrenListeners in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    children - array containing children listeners.
  - setChildrenListeners
```
public void setChildrenListeners(ConsistencyListener child)
```
    Description copied from interface: ConsistencyListener
    
    Setting one child listener.
    
    Specified by:
    
    setChildrenListeners in interface ConsistencyListener
    
    Parameters:
    
    child - the only child listener added to this consistency listener.
  - setChildrenListeners
```
public void setChildrenListeners(ExitChildListener child)
```
    Description copied from interface: ExitChildListener
    
    It adds one child listener.
    
    Specified by:
    
    setChildrenListeners in interface ExitChildListener<T extends IntVar>
    
    Parameters:
    
    child - added child listener.
  - executeAfterConsistency
```
public boolean executeAfterConsistency(boolean consistent)
```
    Description copied from interface: ConsistencyListener
    
    It is executed right after consistency of the current search node. Returning true when the parameter was false is not advised as things like invalid solutions can be found.
    
    Specified by:
    
    executeAfterConsistency in interface ConsistencyListener
    
    Parameters:
    
    consistent - specifies if the consistency call returned true or false.
    
    Returns:
    
    true if the search should continue, false if the search should act as the consistency returned false.
  - addShavingConstraint
```
public void addShavingConstraint(Constraint c)
```
    It adds shaving constraint to the list of constraints guiding shaving.
    
    Parameters:
    
    c - constraint which is added to the list of guiding constraints.
  - setStore
```
public void setStore(Store store)
```
    It specifies the constraint store in which context the shaving will take place.
    
    Parameters:
    
    store - constraint store.

Class Shaving<T extends IntVar>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

onlyFailedConstraint

onlyIntVarsOfFailedConstraint

varsOfFailedConstraint

quickShave

successes

failures

Constructor Detail

Shaving

Method Detail

leftChild

leftChild

rightChild

rightChild

setChildrenListeners

setChildrenListeners

setChildrenListeners

setChildrenListeners

executeAfterConsistency

addShavingConstraint

setStore