Volume 20 (1968)

Table of contents

Preface
p. 1
The scientific work of A. Heyting
p. 3-12
The equivalence of two definitions of elementary formal system
p. 13-20
A note on spread-cardinals
p. 21-28
Persistent and invariant formulas for outer extensions
p. 29-52
Attributes, sets, partial sets and identity
p. 53-69
Existence in mathematics
p. 70-82
Assertions depending on time and corresponding logical calculi
p. 83-87
Relativization with respect to formulas and its use in proofs of independence
p. 88-106
Functional interpretation of bar induction by bar recursion
p. 107-124
Almost direct products and saturation
p. 125-132
Constructive mathematics as a philosophical problem
p. 133-142
Quantifier-free axioms for constructive plane geometry
p. 143-152
Binary generators for the m-valued and ℵ 0 -valued Lukasiewicz propositional calculi
p. 153-169
Axiomatisation indépendante des ensembles dénombrables de formules en logique intuitionniste
p. 170-187
Some thoughts on the history of mathematics
p. 188-193
Extending the topological interpretation to intuitionistic analysis
p. 194-210
New sets of postulates for intuitionistic topology
p. 211-221
Lawless sequences of natural numbers
p. 222-248