Google published a paper which I think is relevant to the topic, Machine Learning: The High Interest Credit Card of Technical Debt (2014). http://research.goog

Google published a paper which I think is relevant to the topic, Machine Learning: The High Interest Credit Card of Technical Debt (2014). http://research.google.com/pubs/pub43146.html http://research.google.com/pubs/pub43146.html The conclusion seems to be that even this level of machine learning decreases controllability substantially. "We note that it is remarkably easy to incur massive ongoing maintenance costs at the system level when applying machine learning."