If you want to know more about how Google Flights works, airline tickets, and why it is super complicated to deal with all the constraints and the combinatorial combinations, I highly recommend this set of slides by Carl de Marcken, one of the co-founders of ITA software, which Google acquired and became one of the underpinnings of Google Flights. (Sorry for the http rather than https Link: Carl's domain doesn't appear to support https) https://t.co/iQgSXyP6D0
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