Invariance of density cardinals under changes outside the open unit interval

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Let all{\mathsf{all}} be the ambient parameter set, and let X,X′⊆allX,X'\subseteq{\mathsf{all}} satisfy

X∖(0,1)=X′∖(0,1).X\setminus(0,1)=X'\setminus(0,1).

Let YY be arbitrary, and write ddX,Y{\mathfrak{dd}}_{X,Y} for the associated density cardinal. Density-cardinal invariance conjecture. If XX and X′X' agree outside (0,1)(0,1), then

ddX,Y=ddX′,Y.{\mathfrak{dd}}_{X,Y}={\mathfrak{dd}}_{X',Y}.

This is presented as a more sweeping conjecture following the singleton-target conjecture, and the paper does not provide a proof or resolution.

References

Primary source

Christina Brech, Jörg Brendle and Márcio Telles, “Density cardinals”, arXiv:2410.21102 (2024).

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