Class Tree

java.lang.Object
org.jacop.constraints.knapsack.Tree

public class Tree extends Object
This tree is a main data structure used and required by Knapsack constraint.
Version:
4.9
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    int
    It specifies the already obtained profit due to the items which are already included in the solution.
    int
    It specifies the already used capacity due to the items which are already included in the solution.
    int
    It specifies the fraction of the critical item which has been not included in the optimal non-integral solution.
    It specifies the leaf containing the critical item.
    int
    It specifies the leaf containing the left most item which is being used during computeForbidden().
    int
    It specifies the leaf containing the last right item which is being used during computeMandatory().
    (package private) TreeNode
    It specifies the current right item of the tree which have been yet included in computation of replaceable weight.
    (package private) int
    It specifies the current profit obtained by all already traversed right items.
    (package private) int
    It specifies the currentWeight from which searching for next mandatory item starts from.
    boolean
    It specifies that computeForbidden part of the consistency function has run out of left mandatory items.
    boolean
    It specifies if the mandatory check has run out of right items to complement mandatory items.
    It specifies the first (counting from left to right), the most efficient item in the tree.
    It specifies the last (counting from left to right), the least efficient item in the tree.
    double
    It specifies the optimalProfit of possibly non-integral solution generated by LP relaxation.
    (package private) double
    It specifies the profit obtained from the remaining part of the critical item.
    (package private) double
    It specifies the profit obtained from the remaining part of the critical item.
    final TreeNode
    It specifies the root of the tree.
    int
    It specifies how much weight is used by an optimal non-fractional solution.
  • Constructor Summary

    Constructors
    Constructor
    Description
    Tree(KnapsackItem[] items, Map<IntVar,TreeLeaf> varPositionMaping, TreeLeaf[] leaves, IntVar zero)
    It constructs a tree out of the list of items and creates proper supporting structures.
    Tree(Tree tree)
    It creates a tree by making a shallow copy.
    Tree(TreeNode node)
    Create a single node tree.
  • Method Summary

    Modifier and Type
    Method
    Description
    int
    computeIntrusionWeight(int weightOfItemChecked, int maxNoOfItems, int profitOfItemChecked, double efficiencyOfItemChecked, double profitSlack)
    It returns the amount of weight of a given item being checked which can be replaced by Right items given the amount of profitSlack.
    int
    computeMinProfit(int minWeight)
    It computes the minimum of capacity variable for knapsack constraint given the minimum requirement for profit.
    int
    computeMinWeight(int minProfit)
    It computes the minimum of capacity variable for knapsack constraint given the minimum requirement for profit.
    int
    computeReplacableWeight(int weightOfItemChecked, int maxNoOfItems, int profitOfItemChecked, double efficiencyOfItemChecked, double profitSlack)
    It returns the amount of weight of a given item being checked which can be replaced by Right items given the amount of profitSlack.
    It finds next leaf of a maximum weight of at least weight, so it can have some parts of it mandatory.
    It finds previous leaf of a maximum weight of at least weight, so it can have some parts of it forbidden.
    int
    getCriticalPosition(int capacity)
    It finds a leaf which reaches the limit of the given capacity.
    Used to search for mandatory
    It returns the last (the least efficient) item in the tree.
    void
    It initializes the private variables required by computation of how much weight we can replace for any Left item.
    void
    It initializes the private variables required by computation of how much weight we can replace for any Left item.
    merge(Tree that)
    A merge method for trees, it added a new root from the ancients
    void
    It recomputes all the attributes of the internal nodes of the knapsack tree.
     
    void
    updateCritical(int capacity)
    It updates information about the critical item, as well as information about fraction of critical item which is not taken.
    void
    updateFromList(List<TreeLeaf> list, int startingPosition)
    Used for updating the tree using a list of nodes that have changed.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
  • Field Details

    • root

      public final TreeNode root
      It specifies the root of the tree.
    • criticalLeaf

      public TreeLeaf criticalLeaf
      It specifies the leaf containing the critical item. The critical item is the one used partially by Linear Programming approach.
    • criticalRightLeaf

      public int criticalRightLeaf
      It specifies the leaf containing the last right item which is being used during computeMandatory(). if max() of the right item after criticalRight is changed then it can be safely ignored.
    • criticalLeftLeaf

      public int criticalLeftLeaf
      It specifies the leaf containing the left most item which is being used during computeForbidden(). if min() of the left item before criticalLeft is changed then it can be safely ignored.
    • first

      public TreeLeaf first
      It specifies the first (counting from left to right), the most efficient item in the tree.
    • last

      public TreeLeaf last
      It specifies the last (counting from left to right), the least efficient item in the tree.
    • optimalProfit

      public double optimalProfit
      It specifies the optimalProfit of possibly non-integral solution generated by LP relaxation.
    • availableWeightOfCriticalItem

      public int availableWeightOfCriticalItem
      It specifies the fraction of the critical item which has been not included in the optimal non-integral solution.
    • takenWeightOfCriticalItem

      public int takenWeightOfCriticalItem
      It specifies how much weight is used by an optimal non-fractional solution.
    • alreadyObtainedProfit

      public int alreadyObtainedProfit
      It specifies the already obtained profit due to the items which are already included in the solution.
    • alreadyUsedCapacity

      public int alreadyUsedCapacity
      It specifies the already used capacity due to the items which are already included in the solution.
    • currentNode

      TreeNode currentNode
      It specifies the current right item of the tree which have been yet included in computation of replaceable weight.
    • currentWeight

      int currentWeight
      It specifies the currentWeight from which searching for next mandatory item starts from. Only items with weight greater or equal to currentWeight can be (partially) mandatory.
    • currentProfit

      int currentProfit
      It specifies the current profit obtained by all already traversed right items.
    • profitFromCriticalLeft

      double profitFromCriticalLeft
      It specifies the profit obtained from the remaining part of the critical item.
    • profitFromCriticalTaken

      double profitFromCriticalTaken
      It specifies the profit obtained from the remaining part of the critical item.
    • exhaustedRightItems

      public boolean exhaustedRightItems
      It specifies if the mandatory check has run out of right items to complement mandatory items.
    • exhaustedLeftItems

      public boolean exhaustedLeftItems
      It specifies that computeForbidden part of the consistency function has run out of left mandatory items.
  • Constructor Details

    • Tree

      public Tree(TreeNode node)
      Create a single node tree.
      Parameters:
      node - a root of this one-node tree.
    • Tree

      public Tree(Tree tree)
      It creates a tree by making a shallow copy.
      Parameters:
      tree - tree to be constructed
    • Tree

      public Tree(KnapsackItem[] items, Map<IntVar,TreeLeaf> varPositionMaping, TreeLeaf[] leaves, IntVar zero)
      It constructs a tree out of the list of items and creates proper supporting structures. It assumes the list of items is greater than 1.
      Parameters:
      items - knapsack items used to create the tree.
      varPositionMaping - mapping of variables into positions within the tree.
      leaves - array of leaves of the created tree.
      zero - it specifies a variable equal to value 0.
  • Method Details

    • merge

      public Tree merge(Tree that)
      A merge method for trees, it added a new root from the ancients
      Parameters:
      that - A tree that is being merged with this tree.
      Returns:
      The tree resulting of the merge of this and that
    • updateCritical

      public void updateCritical(int capacity)
      It updates information about the critical item, as well as information about fraction of critical item which is not taken.
      Parameters:
      capacity - available capacity to be used by knapsack.
    • getCriticalPosition

      public int getCriticalPosition(int capacity)
      It finds a leaf which reaches the limit of the given capacity. Items weight is added from the most efficient to the least efficient.
      Parameters:
      capacity - available capacity to be used by knapsack.
      Returns:
      the position of the item.
    • getFirst

      public TreeLeaf getFirst()
      Used to search for mandatory
      Returns:
      The first item
    • getLast

      public TreeLeaf getLast()
      It returns the last (the least efficient) item in the tree. It is a starting leaf for computeForbidden() part.
      Returns:
      The last item
    • toString

      public String toString()
      Overrides:
      toString in class Object
    • updateFromList

      public void updateFromList(List<TreeLeaf> list, int startingPosition)
      Used for updating the tree using a list of nodes that have changed.
      Parameters:
      list - list of leaves that needs to be updated.
      startingPosition - it specifies the first leaf in the array which has not been updated before.
    • recompute

      public void recompute()
      It recomputes all the attributes of the internal nodes of the knapsack tree.
    • initializeComputeMandatory

      public void initializeComputeMandatory()
      It initializes the private variables required by computation of how much weight we can replace for any Left item.
    • computeReplacableWeight

      public int computeReplacableWeight(int weightOfItemChecked, int maxNoOfItems, int profitOfItemChecked, double efficiencyOfItemChecked, double profitSlack)
      It returns the amount of weight of a given item being checked which can be replaced by Right items given the amount of profitSlack.
      Parameters:
      weightOfItemChecked - the weight of item being checked.
      maxNoOfItems - the maximum number which can be taken of checked items.
      profitOfItemChecked - the profit of the item being checked.
      efficiencyOfItemChecked - the efficiency of the item being checked.
      profitSlack - the amount of reserve profit which can be sacrificed before violating the constraint.
      Returns:
      the amount of weight of a given item that can be replaced by Right items without violating the constraint.
    • findNextLeafAtLeastOfWeight

      public TreeLeaf findNextLeafAtLeastOfWeight(TreeLeaf leaf, int weight)
      It finds next leaf of a maximum weight of at least weight, so it can have some parts of it mandatory.
      Parameters:
      leaf - starting leaf, the result must be to the right of this leaf.
      weight - weight condition which must be satisfied by the found leaf.
      Returns:
      tree leaf on the right to the supplied leaf with at least specified weight.
    • initializeComputeForbidden

      public void initializeComputeForbidden()
      It initializes the private variables required by computation of how much weight we can replace for any Left item.
    • computeIntrusionWeight

      public int computeIntrusionWeight(int weightOfItemChecked, int maxNoOfItems, int profitOfItemChecked, double efficiencyOfItemChecked, double profitSlack)
      It returns the amount of weight of a given item being checked which can be replaced by Right items given the amount of profitSlack.
      Parameters:
      weightOfItemChecked - the weight of item being checked.
      maxNoOfItems - the maximum number which can be taken of checked items.
      profitOfItemChecked - the profit of the item being checked.
      efficiencyOfItemChecked - the efficiency of the item being checked.
      profitSlack - the amount of reserve profit which can be sacrificed before violating the constraint.
      Returns:
      the amount of weight of a given item that can be replaced by Right items without violating the constraint.
    • findPreviousLeafAtLeastOfWeight

      public TreeLeaf findPreviousLeafAtLeastOfWeight(TreeLeaf leaf, int weight)
      It finds previous leaf of a maximum weight of at least weight, so it can have some parts of it forbidden.
      Parameters:
      leaf - starting leaf, the result must be to the left of this leaf.
      weight - weight condition which must be satisfied by the found leaf.
      Returns:
      tree leaf on the left to the supplied leaf with at least specified weight.
    • computeMinWeight

      public int computeMinWeight(int minProfit)
      It computes the minimum of capacity variable for knapsack constraint given the minimum requirement for profit.
      Parameters:
      minProfit - minimum profit obtained by the knapsack.
      Returns:
      it returns the minimum required weight to satisfy min profit requirements.
    • computeMinProfit

      public int computeMinProfit(int minWeight)
      It computes the minimum of capacity variable for knapsack constraint given the minimum requirement for profit.
      Parameters:
      minWeight - - the minimum of weight within a knapsack.
      Returns:
      it returns the minimum required weight to satisfy min profit requirements.