formal-system As a command 10 categories below formal-system Narrow by field-of-study 5 formal-science 5 humanities 5 logic 5 mathematical-logic 5 mathematics 5 philosophy 5 science 5 model-of-computation 3 finite-automaton 1 formal-grammar 1 finite-automaton 1formal-grammar 1classical-logiccontext-free-grammardescription-logiclambda-calculusmodal-logicpropositional-logicpushdown-automatontype-theory