首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Tychonoff expansions with prescribed resolvability properties
Authors:WW Comfort
Institution:a Department of Mathematics and Computer Science, Wesleyan University, Wesleyan Station, Middletown, CT 06459, United States
b Department of Mathematics and Computer Science, Albany State University, Albany, GA 31705, United States
Abstract:The recent literature offers examples, specific and hand-crafted, of Tychonoff spaces (in ZFC) which respond negatively to these questions, due respectively to Ceder and Pearson (1967) 3] and to Comfort and García-Ferreira (2001) 5]: (1) Is every ω-resolvable space maximally resolvable? (2) Is every maximally resolvable space extraresolvable? Now using the method of KID expansion, the authors show that every suitably restricted Tychonoff topological space (X,T) admits a larger Tychonoff topology (that is, an “expansion”) witnessing such failure. Specifically the authors show in ZFC that if (X,T) is a maximally resolvable Tychonoff space with S(X,T)?Δ(X,T)=κ, then (X,T) has Tychonoff expansions U=Ui (1?i?5), with Δ(X,Ui)=Δ(X,T) and S(X,Ui)?Δ(X,Ui), such that (X,Ui) is: (i=1) ω-resolvable but not maximally resolvable; (i=2) if κ is regular, with S(X,T)?κ?κ] τ-resolvable for all τ<κ, but not κ-resolvable; (i=3) maximally resolvable, but not extraresolvable; (i=4) extraresolvable, but not maximally resolvable; (i=5) maximally resolvable and extraresolvable, but not strongly extraresolvable.
Keywords:primary  05A18  03E05  54A10  secondary  03E35  54A25  05D05
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号