On effective compactness and sigma-compactness

Details On effective compactness and sigma-compactness On effective compactness and sigma-compactness

2011-03-05

arxiv.org/abs/1103.1060v1

Mathematics

Logic

Scientific paper

Using the Gandy -- Harrington topology and other methods of effective descriptive set theory, we prove several theorems on compact and sigma-compact pointsets. In particular we show that any $\Sigma^1_1$ set $A$ of the Baire space $N^N$ either is covered by a countable union of compact $\Delta^1_1$ sets, or $A$ contains a subset closed in $N^N$ and homeomorphic to $N^N$ (and then $A$ is not covered by a sigma-compact set, of course).

Affiliated with

Also associated with

No associations

Rating

On effective compactness and sigma-compactness does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On effective compactness and sigma-compactness, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On effective compactness and sigma-compactness will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-8905