def convert_implication_to_and(property_graph):
    """Converts an implication TimedPropertyGraph to an AND form property.

    :param property_graph: An implication TimedPropertyGraph.

    :return: A new TimedPropertyGraph with top level implication operator converted to
            an AND operator.
    """
    if not property_graph.is_implication_graph():
        message = "Error in converting non-implication TimedPropertyGraph to AND form."
        raise RuntimeError(message)

    assumption, conclusion = property_graph.get_top_level_implication_subgraphs()
    assumption = assumption.get_copy()
    assumption.logical_and(conclusion)

    return assumption