4.1.8.3. causality/Petri

class causality.Net

Adaptation of a derivation graph into a Petri net. Importantly, if the underlying derivation graph is enlarged then syncSize() must be called before calling certain other methods on the object.

Added in version 1.1.

Todo

check version added before release

__init__(dg)

Calls syncSize().

Parameters:

dg (DG) – the derivation graph to adapt.

Returns:

a new Petri net, adapting the given derivation graph.

Raises:

LogicError if dg is None.

Raises:

LogicError if neither dg.hasActiveBuilder nor dg.locked.

dg

(Read-only) The underlying derivation graph.

Type:

DG

syncSize()

Enlarges the internal data structures to the current size of the underlying derivation graph.

getPostPlaces(e)
Parameters:

e (DG.HyperEdge) – the hyperedge to find unique targets for.

Returns:

a list of unique targets for the given hyperedge.

Return type:

list[DG.Vertex]

Requires syncSize() to have been called since the last time the underlying derivation graph has changed size.

class causality.Marking

Representation of a marking on a Petri net. Importantly, if the underlying derivation graph is enlarged then syncSize() must be called before calling certain other methods on the object.

Added in version 1.1.

Todo

check version added before release

__init__(net)
Parameters:

net (Net) – the Petri net to construct a marking for.

Raises:

LogicError if net is None.

net

(Read-only) The underlying Petri net.

Type:

Net

syncSize()

Enlarges the internal data structures to the current size of the underlying derivation graph.

Calls net.syncSize().

__eq__()
add(v, c)
add(g, c)

Add c tokens on the place v. The second version is equivalent to self.add(self.net.dg.findVertex(g), c).

Parameters:

  • v (DG.Vertex) – the place to add tokens to.

  • g (Graph) – the graph associated to the place to add tokens to.

  • c (int) – the amount of tokens to add.

Returns:

the new total token count on v.

Return type:

int

Raises:

LogicError if not v.

Raises:

LogicError if v.dg != self.net.dg.

Raises:

LogicError if c < 0.

Raises:

LogicError if g is None.

Raises:

LogicError if !self.net.dg.findVertex(g).

Requires syncSize() to have been called since the last time the underlying derivation graph has changed size.

remove(v, c)
remove(g, c)

Remove c tokens from the place v. The second version is equivalent to self.remove(self.net.dg.findVertex(g), c).

Parameters:

  • v (DG.Vertex) – the place to remove tokens from.

  • g (Graph) – the graph associated to the place to remove tokens from.

  • c (int) – the amount of tokens to remove.

Returns:

the new total token count on v.

Return type:

int

Raises:

LogicError if not v.

Raises:

LogicError if v.dg != self.net.dg.

Raises:

LogicError if c < 0.

Raises:

LogicError if not enough tokens are left to remove all c.

Raises:

LogicError if g is None.

Raises:

LogicError if !self.net.dg.findVertex(g).

Requires syncSize() to have been called since the last time the underlying derivation graph has changed size.

__getitem__(v)
__getitem__(g)
Parameters:

  • v (DG.Vertex) – the place to query the number of tokens for.

  • g (Graph) – the graph associated to the place to query the number of tokens for.

Returns:

the token count for v. The second version is equivalent to self[self.net.dg.findVertex(g)].

Return type:

int

Raises:

LogicError if not v.

Raises:

LogicError if v.dg != self.net.dg.

Raises:

LogicError if g is None.

Raises:

LogicError if !self.net.dg.findVertex(g).

Requires syncSize() to have been called since the last time the underlying derivation graph has changed size.

numTokens

(Read-only) The total number of tokens in the marking.

Type:

int

getAllEnabled()
Returns:

a list of all hyperedges currently enabled for firing.

Return type:

list[DG.HyperEdge]

getNonZeroPlaces()
Returns:

a list of all vertices with tokens.

Return type:

list[DG.Vertex]

getEmptyPostPlaces(e)
Parameters:

e (DG.HyperEdge) – the edge to query for empty post places.

Returns:

a list of all target vertices of the given hyperedge that do not have any tokens. The list represents a set, so if vertex is a target multiple times it will only be included once.

Return type:

list[DG.Vertex]

Raises:

LogicError if not e.

Raises:

LogicError if e.dg != self.net.dg.

isEnabled(e)
Parameters:

e (DG.HyperEdge) – the edge to query for being enabled.

Returns:

whether the given hyperedge is enabled for firing.

Return type:

bool

Raises:

LogicError if not e.

Raises:

LogicError if e.dg != self.net.dg.

fire(e)
Parameters:

e (DG.HyperEdge) – the edge to fire.

Raises:

LogicError if not e.

Raises:

LogicError if e.dg != self.net.dg.

Raises:

LogicError if not self.isEnabled(e).