MDD (JaCoP 4.9.0 API)

java.lang.Object
- org.jacop.util.MDD

```
public class MDD
extends Object
```
Defines an MDD as used in the following paper.
K.C. Cheng and R.H. Yap, "Maintaining generalized arc consistency on ad-hoc n-ary constraints.", CP 2008.

Version:

4.9

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

Fields
Modifier and Type	Field and Description
`int[]`	`diagram` For each node at given index i-th it specifies all possible outgoing edges.
`int[]`	`domainLimits` The initial domain limits used to create an MDD array representation.
`int`	`freePosition` It specifies the first position in the array which is available for use.
`static int`	`NOEDGE` It specifies an identifier which denotes lack of the edge for a given value (in the context of the current level (variable) of an MDD.
`static int`	`START_SIZE` The initial size of the array representing an MDD.
`static int`	`TERMINAL` It specifies an identifier which denotes a terminal node.
`IntVar[]`	`vars` The ordered list of variables participating in MDD.
`IndexDomainView[]`	`views` It creates index domain views so operations based on indexes of values can be performed efficiently.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`MDD()`
	`MDD(IntVar[] vars)` It creates and MDD representation given the list of variables.
	`MDD(IntVar[] vars, int[][] table)` It creates and MDD representation given the list of variables and (dis)allowed tuples.
	`MDD(IntVar[] vars, int[] diagram, int[] domainLimits)` It creates an MDD.
	`MDD(IntVar[] vars, int[] minimumDomainLimits, int[][] table)` It creates and MDD representation given the list of variables and (dis)allowed tuples.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addTuple(int[] tuple)` It allows to add one by one tuple before the reduction of the initial MDD takes place.
`boolean`	`checkIfAllowed()`
`boolean`	`checkIfAllowed(int[] tuple)` It checks if the specified tuple is allowed.
`void`	`ensureSize(int size)` It makes sure that diagram uses an array of at least given size.
`int`	`findPosition(int value, int[] values)` It finds a position of a value inside the array.
`protected int`	`findRange(int value, int[] values)`
`void`	`reduce()` It reduces MDD to minimal size.
`MDD`	`reuse(IntVar[] vars)` If possible it will return an MDD which reuse an array representation of the current MDD.
`String`	`toString()`

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

- Field Detail
  - TERMINAL
```
public static final int TERMINAL
```
    It specifies an identifier which denotes a terminal node.
    
    See Also:
    
    Constant Field Values
  - NOEDGE
```
public static final int NOEDGE
```
    It specifies an identifier which denotes lack of the edge for a given value (in the context of the current level (variable) of an MDD.
    
    See Also:
    
    Constant Field Values
  - vars
```
public IntVar[] vars
```
    The ordered list of variables participating in MDD.
  - domainLimits
```
public int[] domainLimits
```
    The initial domain limits used to create an MDD array representation.
  - diagram
```
public int[] diagram
```
    For each node at given index i-th it specifies all possible outgoing edges. If there was no edge for a value of the variable associated to the current node then the entry corresponding to that value is set to NOEDGE. If a given path specifies an allowed tuple than it is terminated with a terminal node.
  - views
```
public IndexDomainView[] views
```
    It creates index domain views so operations based on indexes of values can be performed efficiently.
  - freePosition
```
public int freePosition
```
    It specifies the first position in the array which is available for use.
  - START_SIZE
```
public static final int START_SIZE
```
    The initial size of the array representing an MDD.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - MDD
```
public MDD(IntVar[] vars,
           int[] diagram,
           int[] domainLimits)
```
    It creates an MDD. Please note that diagram argument which is potentially a very large array and can be used across many constraints is not copied by the constructor but used directly.
    
    Parameters:
    
    vars - variables involved in this multiple-value decision diagram.
    
    diagram - an int array representation of the diagram.
    
    domainLimits - the limits on the number of values imposed on each variable.
  - MDD
```
public MDD(IntVar[] vars,
           int[] minimumDomainLimits,
           int[][] table)
```
    It creates and MDD representation given the list of variables and (dis)allowed tuples. Minimum domain limits allows artificially increase the size of the variable domain to make reuse of the same mdd across multiple constraints possible.
    
    Parameters:
    
    vars - variables and their order used in the MDD.
    
    minimumDomainLimits - it specifies the minimal number of values used for each of the variables.
    
    table - it specifies the allowed tuples which are being converted into an MDD.
  - MDD
```
public MDD(IntVar[] vars,
           int[][] table)
```
    It creates and MDD representation given the list of variables and (dis)allowed tuples. Minimum domain limits allows artificially increase the size of the variable domain to make reuse of the same mdd across multiple constraints possible.
    
    Parameters:
    
    vars - variables and their order used in the MDD.
    
    table - it specifies the allowed tuples which are being converted into an MDD.
  - MDD
```
public MDD(IntVar[] vars)
```
    It creates and MDD representation given the list of variables. The domain limits are set to be equal to the size of the variables domains. The tuples are being added separately one by one.
    
    Parameters:
    
    vars - variables and their order used in the MDD.
  - MDD
```
protected MDD()
```
- Method Detail
  - reuse
```
public MDD reuse(IntVar[] vars)
```
    If possible it will return an MDD which reuse an array representation of the current MDD. It returns null if one of the variables supplied has a larger domain then assumed by respective variable from this MDD. In order to make reuse possible first create MDD for largest size variables.
    
    Parameters:
    
    vars - array of new variables for which this MDD is being reused for.
    
    Returns:
    
    an MDD with parts of it reused for new variables.
  - addTuple
```
public void addTuple(int[] tuple)
```
    It allows to add one by one tuple before the reduction of the initial MDD takes place.
    
    Parameters:
    
    tuple - an allowed tuple being added to MDD.
  - ensureSize
```
public void ensureSize(int size)
```
    It makes sure that diagram uses an array of at least given size.
    
    Parameters:
    
    size - the size the array must be at least of.
  - findPosition
```
public int findPosition(int value,
                        int[] values)
```
    It finds a position of a value inside the array.
    
    Parameters:
    
    value - the value being searched.
    
    values - the array in which the value is being searched for.
    
    Returns:
    
    position of the value in the array.
  - findRange
```
protected int findRange(int value,
                        int[] values)
```
  - reduce
```
public void reduce()
```
    It reduces MDD to minimal size.
  - checkIfAllowed
```
public boolean checkIfAllowed(int[] tuple)
```
    It checks if the specified tuple is allowed.
    
    Parameters:
    
    tuple - the tuple being checked.
    
    Returns:
    
    true if the tuple is allowed, false otherwise.
  - checkIfAllowed
```
public boolean checkIfAllowed()
```
    Returns:
    
    true only if all variables are grounded and the values assigned to variables are allowed by a MDD.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class MDD

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

TERMINAL

NOEDGE

vars

domainLimits

diagram

views

freePosition

START_SIZE

Constructor Detail

MDD

MDD

MDD

MDD

MDD

Method Detail

reuse

addTuple

ensureSize

findPosition

findRange

reduce

checkIfAllowed

checkIfAllowed

toString