Decidability of Boolean algebras with ideal quantification

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Let λ\lambda be a cardinal satisfying

λ≤2ℵ0.\lambda\leq 2^{\aleph_0}.

A Boolean algebra has ideal quantification when its first-order language is expanded by allowing quantification over ideals.

Boolean-algebra decidability conjecture. The theory of Boolean algebras of cardinality less than λ\lambda, or the first-order theory of Boolean algebras expanded by quantification over ideals, is decidable when

λ≤2ℵ0,\lambda\leq 2^{\aleph_0},

including the case λ=ℵ2≤2ℵ0\lambda=\aleph_2\leq 2^{\aleph_0}.

The parser supplies no resolution for this candidate. The surrounding text relates it to decidability results for countable Boolean algebras and linear orders, but does not establish the stated cardinal-general assertion.

References

Primary source

Saharon Shelah, “The monadic theory of order”, arXiv:2305.00968 (2023).

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