Blurb::
Throttle the depth for a partial recursion of admissible DAGs

Description::
A partial recursion includes admissible directed acyclic graphs (DAGs) up to
a specified depth.  For example, an ACV graph has all approximation models
paired with the truth model, so all graph edges point from each approximation
node to the root node, resulting in a graph depth of 1.  In another example, an MFMC
graph has each approximation node point to the next node in the mode sequence, ending
at the root node; this results in a depth equal to the number of approximation models.

By specifying a ``depth_limit``, one can obtain an intermediate number of
DAGs to be explored within the search, which can be useful when the number of
DAGs for a ``full_recursion`` grows large.

Topics::

Examples::

.. code-block::

    method,
    	model_pointer = 'ENSEMBLE'
    	approximate_control_variate acv_mf
    	  pilot_samples = 25 seed = 8674132
    	  search_model_graphs
    	    partial_recursion depth_limit = 2
    	  max_function_evaluations = 500

Theory::

Faq::

See_Also::
