Class ReachabilityGraph

java.lang.Object
org.tweetyproject.logics.petri.syntax.reachability_graph.ReachabilityGraph
All Implemented Interfaces:
Iterable<Marking>, BeliefBase, GeneralGraph<Marking>, Graph<Marking>
public class ReachabilityGraph extends Object implements Graph<Marking>, BeliefBase
A class to describe the graph of reachability between possible markings of a Petri net
Author:
Benedikt Knopp

  • Constructor Details

    • ReachabilityGraph

      public ReachabilityGraph(PetriNet petriNet)
      Create a new instance
      Parameters:
      petriNet - the underlying Petri net

  • Method Details

    • add

      public boolean add(Marking node)
      Description copied from interface: Graph
      Adds the given node to this graph.
      Specified by:
      add in interface Graph<Marking>
      Parameters:
      node - some node.
      Returns:
      "true" iff the edge has been added successfully.

    • add

      public boolean add(MarkingEdge edge)
      add a marking edge to this graph
      Parameters:
      edge - the edge
      Returns:
      true iff adding the edge was successful

    • add

      public boolean add(GeneralEdge<Marking> edge)
      Description copied from interface: Graph
      Adds the given edge to this graph. If at least one of the nodes the given edge connects is not in the graph, an illegal argument exception is thrown.
      Specified by:
      add in interface Graph<Marking>
      Parameters:
      edge - some edge.
      Returns:
      "true" iff the edge has been added successfully.

    • getNodes

      public List<Marking> getNodes()
      Description copied from interface: Graph
      Returns the nodes of this graph.
      Specified by:
      getNodes in interface GeneralGraph<Marking>
      Specified by:
      getNodes in interface Graph<Marking>
      Returns:
      the nodes of this graph.

    • getNumberOfNodes

      public int getNumberOfNodes()
      Description copied from interface: Graph
      Returns the number of nodes in this graph.
      Specified by:
      getNumberOfNodes in interface Graph<Marking>
      Returns:
      the number of nodes in this graph.

    • getNumberOfEdges

      public int getNumberOfEdges()
      the number of edges in this graph
      Specified by:
      getNumberOfEdges in interface Graph<Marking>
      Returns:
      the number of edges in this graph

    • areAdjacent

      public boolean areAdjacent(Marking a, Marking b)
      Description copied from interface: Graph
      Returns "true" iff the two nodes are connected by a directed edge from a to b or an undirected edge.
      Specified by:
      areAdjacent in interface Graph<Marking>
      Parameters:
      a - some node
      b - some node
      Returns:
      "true" iff the two nodes are connected by a directed edge from a to b or an undirected edge.

    • getEdge

      public Edge<Marking> getEdge(Marking a, Marking b)
      Description copied from interface: Graph
      Returns the corresponding edge (a,b) if a and b are adjacent. Otherwise it returns null.
      Specified by:
      getEdge in interface Graph<Marking>
      Parameters:
      a - some node
      b - some node
      Returns:
      the edge (a,b) or null.

    • getEdges

      public List<MarkingEdge> getEdges()
      Description copied from interface: Graph
      Returns the edges of this graph.
      Specified by:
      getEdges in interface GeneralGraph<Marking>
      Specified by:
      getEdges in interface Graph<Marking>
      Returns:
      the edges of this graph.

    • getPetriNet

      public PetriNet getPetriNet()
      Return the petriNet
      Returns:
      the petriNet

    • setPetriNet

      public void setPetriNet(PetriNet petriNet)
      Setter petriNet
      Parameters:
      petriNet - the petriNet to set

    • getProbabilityFunction

      public ProbabilityFunction<MarkingEdge> getProbabilityFunction()
      the probability function of this graph, which is null for default
      Returns:
      the probabilityFunction

    • setProbabilityFunction

      public void setProbabilityFunction(ProbabilityFunction<MarkingEdge> probabilityFunction)
      sets the probability function of this graph
      Parameters:
      probabilityFunction - the probability function to set

    • initializeDefaultProbabilityFunction

      public void initializeDefaultProbabilityFunction()
      initializes a probability function over the edges of this graph according to Random Walk, i.e. all outgoing edges of one particular node are assigned to the same probability and the sum of these probabilities equals to 1.

    • initializeRandomProbabilityFunction

      public void initializeRandomProbabilityFunction()
      Initialize a probability function over the edges of this graph according to a stochastic walk. The sum of probabilities of outgoing edges at each node equals to 1, and for multiple outgoing edges, probabilities are randomized.

    • initializeIrregularProbabilityFunction

      public void initializeIrregularProbabilityFunction()
      Initialize a probability function over the edges of this graph according to a stochastic walk. For multiple outgoing edges, exactly one edge receives a probability of 1 and all other edges a probability of 0. This may turn some transitions dead.

    • hasValidProbabilityFunction

      public boolean hasValidProbabilityFunction()
      specifies if the probability function of this graph is 1. initialized, and 2. assigns for each marking a total (summed up) probability of 1 for all successor edges. This implies that each marking needs to have at least one successor marking.
      Returns:
      true iff the probability function is valid

    • sortMarkings

      public void sortMarkings()
      fix the sorting to prepare linear algebra analysis in particular, assert a fixed ordering for index-based matrix/vector-access

    • getTransitionMatrix

      public Matrix getTransitionMatrix() throws IllegalStateException
      Retrieve a matrix that specifies for each pair of markings how likely a transition between these markings is going to happen, based on the probability function that describes this graph.
      Returns:
      the transition matrix
      Throws:
      IllegalStateException - iff the probability function of this graph is invalid

    • getControlMatrix

      public Matrix getControlMatrix()
      Retrieve a matrix that specifies for each pair of marking and transition how likely that transition is going to occur at that marking, based on the probability function that describes this graph.
      Returns:
      the control matrix
      Throws:
      IllegalStateException - iff the probability function of this graph is invalid

    • iterator

      public Iterator<Marking> iterator()
      Specified by:
      iterator in interface Graph<Marking>
      Specified by:
      iterator in interface Iterable<Marking>

    • contains

      public boolean contains(Object obj)
      Description copied from interface: Graph
      Returns "true" when this graph contains the given node or edge.
      Specified by:
      contains in interface Graph<Marking>
      Parameters:
      obj - an object
      Returns:
      "true" if this graph contains the given node or edge.

    • getChildren

      public Collection<Marking> getChildren(Node node)
      Description copied from interface: Graph
      Returns the set of children (node connected via an undirected edge or a directed edge where the given node is the parent) of the given node.
      Specified by:
      getChildren in interface Graph<Marking>
      Parameters:
      node - some node (must be in the graph).
      Returns:
      the set of children of the given node.

    • getParents

      public Collection<Marking> getParents(Node node)
      Description copied from interface: Graph
      Returns the set of parents (node connected via an undirected edge or a directed edge where the given node is the child) of the given node.
      Specified by:
      getParents in interface Graph<Marking>
      Parameters:
      node - some node (must be in the graph).
      Returns:
      the set of parents of the given node.

    • existsDirectedPath

      public boolean existsDirectedPath(Marking node1, Marking node2)
      Description copied from interface: Graph
      Checks whether there is a (directed) path from node1 to node2.
      Specified by:
      existsDirectedPath in interface Graph<Marking>
      Parameters:
      node1 - some node.
      node2 - some node.
      Returns:
      "true" if there is a directed path from node1 to node2.

    • getNeighbors

      public Collection<Marking> getNeighbors(Marking node)
      Description copied from interface: Graph
      Returns the set of neighbors of the given node.
      Specified by:
      getNeighbors in interface Graph<Marking>
      Parameters:
      node - some node (must be in the graph).
      Returns:
      the set of neighbors of the given node.

    • getAdjacencyMatrix

      public Matrix getAdjacencyMatrix()
      Description copied from interface: Graph
      Returns the adjacency matrix of this graph (the order of the nodes is the same as returned by "iterator()").
      Specified by:
      getAdjacencyMatrix in interface Graph<Marking>
      Returns:
      the adjacency matrix of this graph

    • getComplementGraph

      public Graph<Marking> getComplementGraph(int selfloops)
      Description copied from interface: Graph
      Returns the complement graph of this graph, i.e. the graph on the same set of vertices as this graph that connects two vertices v and w with an edge if and only if v and w are not connected in this graph.
      Specified by:
      getComplementGraph in interface Graph<Marking>
      Parameters:
      selfloops - Indicates how to deal with selfloops:
      IGNORE_SELFLOOPS - ignore self loops (don't add and don't remove)
      INVERT_SELFLOOPS - deal with self loops like ordinary edges (add if not present and remove if present)
      REMOVE_SELFLOOPS - simple remove self loops, but don't add new ones.
      Returns:
      the complement graph of this graph.

    • getConnectedComponents

      public Collection<Collection<Marking>> getConnectedComponents()
      Description copied from interface: Graph
      Returns the set of (simple) connected components of this graph. A set of nodes is connected, if there is some path (ignoring edge directions) from each node to each other. It is a connected component if it is connected and maximal wrt. set inclusion.
      Specified by:
      getConnectedComponents in interface Graph<Marking>
      Returns:
      the connected components of this graph.

    • getStronglyConnectedComponents

      public Collection<Collection<Marking>> getStronglyConnectedComponents()
      Description copied from interface: Graph
      Returns the strongly connected components of this graph. A set of nodes is strongly connected, if there is a path from each node to each other. A set of nodes is called strongly connected component if it is strongly connected and maximal with respect to set inclusion.
      Specified by:
      getStronglyConnectedComponents in interface Graph<Marking>
      Returns:
      the strongly connected components of this graph.

    • getSubgraphs

      public Collection<Graph<Marking>> getSubgraphs()
      Description copied from interface: Graph
      Returns the set of sub graphs of this graph.
      Specified by:
      getSubgraphs in interface Graph<Marking>
      Returns:
      the set of sub graphs of this graph.

    • getRestriction

      public Graph<Marking> getRestriction(Collection<Marking> nodes)
      Description copied from interface: GeneralGraph
      Returns a copy of this graph that contains only the specified nodes and all corresponding edges between them.

      This method generates a subgraph (or restricted graph) from the current graph by including only the given nodes and the edges that connect them. The returned graph is a new instance and does not modify the original graph.

      Specified by:
      getRestriction in interface GeneralGraph<Marking>
      Parameters:
      nodes - a collection of nodes to be included in the restricted graph.
      Returns:
      a `GeneralGraph` object representing the restricted graph.

    • hasSelfLoops

      public boolean hasSelfLoops()
      Description copied from interface: Graph
      Returns "true" iff the graph has a self loop (an edge from a node to itself).
      Specified by:
      hasSelfLoops in interface Graph<Marking>
      Returns:
      "true" iff the graph has a self loop (an edge from a node to itself).

    • isWeightedGraph

      public boolean isWeightedGraph()
      Description copied from interface: Graph
      Checks whether this graph only contains weighted edges.
      Specified by:
      isWeightedGraph in interface Graph<Marking>
      Returns:
      "true" if all edges are weighted in this graph.

    • hasMarking

      public boolean hasMarking(Marking marking)
      Determine if the specified marking is present as a node in the graph
      Parameters:
      marking - the marking
      Returns:
      true if the marking is present

    • getMarking

      public Optional<Marking> getMarking(Marking marking)
      Retrieve, if present, the marking in this graph that equals the query marking in the sense that both markings describe the same token distribution over places
      Parameters:
      marking - the query marking
      Returns:
      the marking that equals the query marking, or null if not present

    • getOutgoing

      public Set<MarkingEdge> getOutgoing(Marking marking)
      For one particular marking, retrieve all outgoing edges
      Parameters:
      marking - the marking of interest
      Returns:
      the sequence flow successors

    • checkConsistency

      public boolean checkConsistency()
      check if all nodes (markings) of this graph describe the same Petri net, i.e. the same set of places
      Returns:
      true iff all markings describe the same set of places

    • getMinimalSignature

      public Signature getMinimalSignature()
      Description copied from interface: BeliefBase
      Returns the signature of the language of this knowledge base.
      Specified by:
      getMinimalSignature in interface BeliefBase
      Returns:
      the signature of the language of this knowledge base.

    • getInitialMarkings

      public Set<Marking> getInitialMarkings()
      Retrieve the designated initial markings
      Returns:
      getInitialMarkings

    • isInitial

      public boolean isInitial(Marking marking)
      Check whether a marking is a designated initial marking
      Parameters:
      marking - the marking to check
      Returns:
      true iff the marking is initial

    • getMarkings

      public List<Marking> getMarkings()
      Retrieve the markings
      Returns:
      markings