logDebug( "Belief update for :" + start_belief.getAssetID() );
if ( _logger.isDebugEnabled() ) _logger.debug( "Belief update for :" + start_belief.getAssetID() );
    public BeliefState updateBeliefState( BeliefState start_belief,                                          BeliefUpdateTrigger trigger )            throws BelievabilityException    {        if (( start_belief == null )            || ( trigger == null ))            throw new BelievabilityException                    ( "ModelManager.updateBeliefState()",                      "NULL parameters(s) passed in." );        POMDPAssetModel pomdp_model                = getPOMDPModel( start_belief.getAssetType() );        logDebug( "Belief update for :" + start_belief.getAssetID() );        return pomdp_model.updateBeliefState( start_belief,                                              trigger );    } // method updateBeliefState