Spaces with a dispersion point are not cut point spaces - #1829
Merged
Conversation
felixpernegger
approved these changes
Aug 14, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Replace T928
has a dispersion point + size at least 3 => not homogeneouswith a stronger versionhas a dispersion point => not a cut point space.This allows to derive that two more spaces are not cut point spaces:
https://topology.pi-base.org/spaces?q=Has+a+dispersion+point+%2B+%3FCut+point+space
The old T928 result can be derived from the new version together with existing theorems:
https://topology.pi-base.org/spaces?q=Has+a+dispersion+point+%2B+Cardinality+%24%5Cgeq+3%24+%2B+Homogeneous