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ArticleOriginal scientific text

Title

Normal subspaces in products of two ordinals

Authors ¹, ², ³, ⁴

Affiliations

Department of Mathematics, Faculty of Education, Oita University, Dannoharu, Oita, 870-11, Japan
Department of Mathematics, Faculty of Science, Ehime University, Matsuyama, Japan
Department of Mathematical Sciences, Franklin College, Franklin, Indiana 46131, U.S.A.
Department of Mathematics, Kanagawa University, Yokohama 221, Japan

Abstract

Let λ be an ordinal number. It is shown that normality, collectionwise normality and shrinking are equivalent for all subspaces of

{(λ + 1)}^{2}

.

Keywords

(collectionwise) normal, shrinking, product space

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[Ku] K. Kunen, Set Theory. An Introduction to Independence Proofs, North-Holland, Amsterdam, 1980.