TABLE OF CONTENTS

Foreword v

Sets constructible using LKK

By C. C. CHANG 1

Comments on the foundations of set theory

By PAUL J. COHEN 9

Unsolved problems in set theory

By P. ERDOS and A. HAJNAL 17

A more explicit set theory

By HARVEY FRIEDMAN 49

Sets, semisets, models

By PETR HAJEK 67

The Boolean prime ideal theorem does not imply the axiom of choice

By J. D. HALPERN and A. LEVY 83

On models for set theory without AC

By THOMAS JECH 135

Primitive recursive set functions

By RONALD B. JENSEN and CAROL KARP 143

End extensions of models of set theory

By H. JEROME KEISLER and JACK H. SILVER 177

Observations on popular discussions of foundations

By G. KREISEL 189

Indescribability and the continuum

By KENNETH KUNEN 199

The sizes of the indescribable cardinals

By AZRIEL LEVY 205

On the logical complexity of several axioms of set theory

By AZRIEL LEVY 219

Categorical algebra and set-theoretic foundations

By SAUNDERS MAC LANE 231

The solution of one of Ulam's problems concerning analytic rectangles

By R. MANSFIELD 241

Predicative classes

By YIANNIS N. MOSCHOVAKIS 247

iii