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Borel decomposition into an injective part and a countable-image part

Ascertain whether for every Borel function f between Polish zero-dimensional spaces there exists a Borel partition (A,B) of the domain such that the restriction f|A is continuously equivalent to an injection and the restriction f|B has countable image.

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Background

This decomposition conjecture, if true, would separate complexity in Borel functions into a part reducible to injectivity and a part with countable image. It would provide a pathway to proving bqo for broader function classes by handling injective and countable-image components separately.

References

This was [Question 5.6] we upgrade it here to the status of conjecture, and we do the same for the next question.

Conjecture Given any Borel function f between Polish (zero-dimen-sional) spaces, there is a Borel partition (A,B) of dom f such that f{A} is continuously equivalent to an injection, and f{B} has countable image.

A well-quasi-order for continuous functions (2410.13150 - Carroy et al., 17 Oct 2024) in Section 7.3 (DirectionPolish)