The web giants have been investing heavily in artificial intelligence engines to drive new user experiences and to power big data analytics. Indeed, this has become a primary area of competition for Google, Facebook, Microsoft, Baidu and others. One of the most visible results of these deep machine learning platforms is the emergence of personal digital assistants such as Apple Siri, Google Now and Microsoft Cortana – and now Facebook is joining the race with a service called M. The social media giant is testing the digital assistant, according to David Marcus, the firm’s VP of messaging products. It will run inside the Messenger mobile app and will be able to carry out tasks such as booking appointments and travel…