Precise bounds for the sequential order of products of some Fréchet topologies

✍ Scribed by Szymon Dolecki; Saliou Sitou

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 1017 KB
• Volume: 84
• Category: Article
• ISSN: 0166-8641
• DOI: 10.1016/s0166-8641(97)00083-7

✦ Synopsis

The sequential order of a topological space is the least ordinal for which the corresponding iteration of the sequential closure is idempotent. Lower estimates for the sequential order of the product of two regular Fr&het topologies and upper estimates for the sequential order of the product of two subtransverse topologies are given in terms of their fascicularity and sagittality. It is shown that for every countable ordinal cy, there exists a LaHnev topology such that the sequential order of its square is equal to CL 0 1998 Elsevier Science B.V.