Understanding trigger-action programs through novel visualizations of program diferences

Abstract

Trigger-action programming (if-this-then-that rules) empowers non-technical users to automate services and smart devices. As a user's set of trigger-action programs evolves, the user must reason about behavior diferences between similar programs, such as between an original program and several modifcation candidates, to select programs that meet their goals. To facilitate this process, we co-designed user interfaces and underlying algorithms to highlight diferences between trigger-action programs. Our novel approaches leverage formal methods to efciently identify and visualize diferences in program outcomes or abstract properties. We also implemented a traditional interface that shows only syntax diferences in the rules themselves. In a between-subjects online experiment with 107 participants, the novel interfaces better enabled participants to select trigger-action programs matching intended goals in complex, yet realistic, situations that proved very difcult when using traditional interfaces showing syntax diferences.