 Brouwer, Luitzen Egbertus Jan |  category theory |  choice, axiom of |  logic, history of: intuitionistic logic |  logic: intuitionistic |  mathematics, philosophy of |  mathematics, philosophy of: intuitionism |  mathematics: constructive |  paradoxes: and contemporary logic |  proof theory |  semantics: proof-theoretic |  set theory |  set theory: alternative axiomatic theories |  set theory: early development |  set theory: non-wellfounded |  type theory |  type theory: intuitionistic 