 algebra of logic tradition |  Boolean algebra: the mathematics of |  logic: algebraic propositional |  logic: classical |  logic: deontic |  logic: hybrid |  logic: intensional |  logic: many-valued |  logic: modal |  logic: relevance |  logic: temporal |  Łukasiewicz, Jan |  modality: medieval theories of |  possibilism-actualism debate |  possible objects |  possible worlds |  Prior, Arthur 