Retailers look past apps to the next frontier of digital shopping: Chatbots

Artificial intelligence is being touted as a tool for addressing some of humanity's most pressing problems, including climate change and cancer.

But starting this week, you can put it to work for something a little more prosaic: Ordering a hoagie.

On Tuesday, MasterCard announced it has partnered with Subway and two other major merchants to launch "chatbots,"…