.. _method-multifidelity_sampling-search_model_graphs:

"""""""""""""""""""
search_model_graphs
"""""""""""""""""""


Perform a search over admissible model relationships for a given model ensemble



.. toctree::
   :hidden:
   :maxdepth: 1

   method-multifidelity_sampling-search_model_graphs-model_selection
   method-multifidelity_sampling-search_model_graphs-no_recursion
   method-multifidelity_sampling-search_model_graphs-full_recursion


**Specification**

- *Alias:* None

- *Arguments:* None

- *Default:* NO_GRAPH_RECURSION


**Child Keywords:**

+-------------------------+--------------------+---------------------+-----------------------------------------------+
| Required/Optional       | Description of     | Dakota Keyword      | Dakota Keyword Description                    |
|                         | Group              |                     |                                               |
+=========================+====================+=====================+===============================================+
| Optional                                     | `model_selection`__ | Perform a recursion of admissible model       |
|                                              |                     | subsets for a given model ensemble            |
+-------------------------+--------------------+---------------------+-----------------------------------------------+
| Required (Choose One)   | DAG Ensemble       | `no_recursion`__    | Do not recur over admissible DAGs for a given |
|                         | Generation Option  |                     | model ensemble                                |
|                         |                    +---------------------+-----------------------------------------------+
|                         |                    | `full_recursion`__  | Perform a full recursion of all admissible    |
|                         |                    |                     | DAGs for a given model ensemble               |
+-------------------------+--------------------+---------------------+-----------------------------------------------+

.. __: method-multifidelity_sampling-search_model_graphs-model_selection.html
__ method-multifidelity_sampling-search_model_graphs-no_recursion.html
__ method-multifidelity_sampling-search_model_graphs-full_recursion.html



**Description**


Referring to generalized ACV
(:dakkw:`method-approximate_control_variate-search_model_graphs` and
:cite:p:`Bomarito2022`), MFMC is a special case of generalized ACV-MF
(:dakkw:`method-approximate_control_variate-acv_multifidelity`) where a
hierarchical DAG is employed across the model approximations.  As such,
a MFMC method specification that includes graph search forwards to the
generalized ACV solver, but with fixing the DAG to be hierarchical
(each approximation node points to the next approximation of higher
fidelity/resolution, ending with the truth model at the root node) and
fixing the sampling scheme to be ACV-MF.

While the use of a hierarchical DAG is required, the approximation
selections and orderings within this DAG can be varied, so generalized
ACV capabilities for model graph search (see
:dakkw:`method-multifidelity_sampling-search_model_graphs-full_recursion`)
and model selection (see
:dakkw:`method-multifidelity_sampling-search_model_graphs-model_selection`)
are available.