HCI. The 'front-end' encompasses far more than just web dev, and some of it is quite interesting. VR? Smart cars? AI? People all need to interact with them

HCI. The 'front-end' encompasses far more than just web dev, and some of it is quite interesting. VR? Smart cars? AI? People all need to interact with them. Even standard web app problems can get quite complex on the UI. For example, recently I've had to use finite automona to verify that a combination of options on a form can result in all possible valid combinations. Since it was quite complex, I was worried that there was either: a) an invalid path in the options, or b) a valid but unreachable path.