.. _method-approximate_control_variate-search_model_graphs-model_selection:

"""""""""""""""
model_selection
"""""""""""""""


Perform a recursion of admissible model subsets for a given model ensemble



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



**Specification**

- *Alias:* None

- *Arguments:* None


**Description**


For the ACV (:cite:p:`GORODETSKY2020109257`) and
generalized ACV (:cite:p:`Bomarito2022`) methods, this option specifies
an enumerative search over all model subsets for a given model ensemble.
In the ACV case, there is a single DAG definition per model subset;
thus this keyword is only used to search over possible subsets given
this fixed ACV DAG.  For generalized ACV, model selection may be
combined with enumeration of admissible DAGs using different DAG
recursion throttles.

The model subset (and DAG definition) with the best performance
(lowest estimator variance for a prescribed budget or lowest cost for
a prescribed accuracy) is selected for final post-processing.




**Examples**



.. code-block::
    
    method,
    	model_pointer = 'ENSEMBLE'
            approximate_control_variate acv_mf
    	  pilot_samples = 50 seed = 8674132
    	  search_model_graphs
    	    no_recursion		      # ACV case
    #	    kl_recursion  		      # GenACV case 1 of 3
    #	    partial_recursion depth_limit = 2 # GenACV case 2 of 3
    #	    full_recursion    		      # GenACV case 3 of 3
    	    model_selection		      # this option
    	  max_function_evaluations = 500