John F. Horty and Nuel Belnap are contemporary American analytic philosophers known for their collaborative and individual work in philosophical logic, deontic logic, and the semantics of agency. Horty (University of Maryland) is noted for his work on default logic and stit (seeing-to-it-that) theory, while Belnap (University of Pittsburgh) pioneered relevance logic, branching time semantics, and the logic of questions.
Co-developed stit (seeing-to-it-that) theory for the logic of agency and action
Belnap pioneered relevance logic and four-valued logic (FDE)
Horty authored 'Agency and Deontic Logic' and 'Reasons as Defaults'
Developed branching time semantics for indeterminism and future contingents
Advanced formal treatments of deontic logic and normative reasoning