Year: 2026
Type: preprint
Abstract: We isolate an algebraic limit-filter construction for countable-support symmetric iterations built from coherent successor-stage symmetric systems. At limits of uncountable cofinality, countably many generators and their conjugating automorphisms are bounded below the limit; at limits of cofinality $ω$, countable-intersection closure is imposed in the definition. The resulting limit filters are normal and $ω_1$-complete. This gives a ground-coded syntactic closure result: the canonical tuple of a ground-model countable sequence of hereditarily symmetric names is hereditarily symmetric. We also recall the standard symmetric-extension theorem yielding $\mathrm{ZF}$ from a genuine symmetric system. The previously claimed preservation of $\mathrm{DC}$ and the unordered-pairs application are withdrawn. Filter completeness alone does not turn the ground-coded tuple statement into closure under arbitrary countable sequences in the forcing extension. Moreover, every nonempty finite set of reals has a lexicographically least element in $\mathrm{ZF}$, so a family of two-element sets of reals without a choice function cannot exist. The present paper retains only the corrected limit-filter observations and the explicitly qualified symmetric-name consequences.
Source: arXiv (Cornell University)
Author: Gilson, Frank
Subfield: Geometry and Topology
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7124715632
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