.. _py-Derivation:

**********************************************************
Derivation
**********************************************************
.. default-domain:: py

.. py:currentmodule:: mod
.. cpp:namespace:: mod

.. class:: Derivation

    This class is a simple wrapper for passing data around.
    It contains two multisets of graphs :math:`G` and :math:`H`,
    and optionally a rule :math:`p`.
    An object may thus implicitly store a set of direct derivations
    :math:`G\Rightarrow^p H`, though the validity of the data is not checked.

    An object of this class is implicitly convertible to a :class:`Derivations` object.

    .. attribute:: left

        Represents the multi-set of left graphs :math:`G`.

        :type: list[Graph]
    .. attribute:: rule

        Represents the transformation rule :math:`p`, or no rule at all.

        :type: Rule
    .. attribute:: right

        Represents the multi-set of right graphs :math:`H`.

        :type: list[Graph]
.. class:: Derivations

    This class is a simple wrapper for passing data around.
    It contains two multisets of graphs :math:`G` and :math:`H`,
    and (possibly empty) set of rules.
    An object may thus implicitly store a set of direct derivations
    :math:`G\Rightarrow^p H` for each rule :math:`p`,
    though the validity of the data is not checked.

    .. attribute:: left

        Represents the multi-set of left graphs :math:`G`.

        :type: list[Graph]
    .. attribute:: rules

        Represents a (possibly empty) set of transformation rules.

        :type: list[Rule]
    .. attribute:: right

        Represents the multi-set of right graphs :math:`H`.

        :type: list[Graph]