3.1.8.3. causality/Petri¶

class mod.PetriNet¶

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.

__init__(self, 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 (DGHyperEdge) – the hyperedge to find unique targets for.
Returns: a list of unique targets for the given hyperedge.
Return type: list[DGVertex]

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

class mod.PetriNetMarking¶

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.

__init__(net)¶

Parameters: net (PetriNet) – the Petri net to construct a marking for.
Raises: LogicError if net is None.

net¶

(Read-only) The underlying Petri net.

Type: PetriNet

syncSize()¶

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

Calls net.syncSize().

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

add(v, c)¶

Add c tokens on the place v.

Parameters

v (DGVertex) – 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.

Throws

LogicError if c < 0.

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

remove(v, c)¶

Remove c tokens from the place v.

Parameters

v (DGVertex) – 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.

Throws

LogicError if c < 0.

Throws

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

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

__getitem__(v)¶

Parameters: v (DGVertex) – the place to remove tokens from.
Returns: the token count for v.
Return type: int
Raises: LogicError if not v.
Raises: LogicError if v.dg != self.net.dg.

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[DGHyperEdge]

getNonZeroPlaces()¶

Returns: a list of all vertices with tokens.
Return type: list[DGVertex]

getEmptyPostPlaces(e)¶

Parameters: e (DGHyperEdge) – 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[DGVertex]
Raises: LogicError if not e.
Raises: LogicError if e.dg != self.net.dg.

isEnabled(e)¶

Parameters: e (DGHyperEdge) – 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 (DGHyperEdge) – the edge to fire.
Raises: LogicError if not e.
Raises: LogicError if e.dg != self.net.dg.
Raises: LogicError if not self.isEnabled(e).