Preface
The scientific work of A. Heyting
The equivalence of two definitions of elementary formal system
A note on spread-cardinals
Persistent and invariant formulas for outer extensions
Attributes, sets, partial sets and identity
Existence in mathematics
Assertions depending on time and corresponding logical calculi
Relativization with respect to formulas and its use in proofs of independence
Functional interpretation of bar induction by bar recursion
Almost direct products and saturation
Constructive mathematics as a philosophical problem
Quantifier-free axioms for constructive plane geometry
Binary generators for the m-valued and ℵ 0 -valued Lukasiewicz propositional calculi
Axiomatisation indépendante des ensembles dénombrables de formules en logique intuitionniste
Some thoughts on the history of mathematics
Extending the topological interpretation to intuitionistic analysis
New sets of postulates for intuitionistic topology
Lawless sequences of natural numbers