Skip to content

S226: Gluing of Fortissimo and Sierpinski spaces#1810

Open
prabau wants to merge 1 commit into
mainfrom
fortiss-sierp-quotient
Open

S226: Gluing of Fortissimo and Sierpinski spaces#1810
prabau wants to merge 1 commit into
mainfrom
fortiss-sierp-quotient

Conversation

@prabau

@prabau prabau commented Jun 30, 2026

Copy link
Copy Markdown
Collaborator

New S226: Fortissimo space of size $\aleph_1$​ and Sierpinski space glued at their limit points.

This provides an example of both of these:
π-Base, Search for Well-based + Has countable $\pi$-character + ~First countable
π-Base, Search for Almost discrete + ~ Sequentially discrete + ~ Countably tight

As discussed in #1712 (comment) and #1807 (comment).

@prabau prabau added the space label Jun 30, 2026
Comment thread spaces/S000226/README.md

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think it may be slightly easier to avoid quotients all together (or at least as one possible construction)? I.e. a space of size aleph1 with two special points p and q such that every points except p is isloated and ....

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants