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Montel: compactness and omitted-value criteria for holomorphic families

Contribution grade

Complex analysis and normal families · Exact theorem and reusable mathematical method

Reference score460,000Provisional editorial estimate of this exact contribution; its grade is assessed separately.

What changed

An unruly list of complex differentiable functions can contain a well-behaved subsequence. Montel’s 1907 compactness criterion extracts a locally uniformly convergent subsequence from a locally uniformly bounded holomorphic family. His 1912 work adds a different route: a holomorphic family that omits two shared distinct finite values is normal, allowing a subsequence to diverge uniformly to infinity. These criteria turn questions about many functions into questions about one limiting function.

Scientific scope

An unruly list of complex differentiable functions can contain a well-behaved subsequence. Montel’s 1907 compactness criterion extracts a locally uniformly convergent subsequence from a locally uniformly bounded holomorphic family. His 1912 work adds a different route: a holomorphic family that omits two shared distinct finite values is normal, allowing a subsequence to diverge uniformly to infinity. These criteria turn questions about many functions into questions about one limiting function. Convergence is local uniform convergence inside a complex domain, not uniform convergence up to every boundary or convergence of the whole original sequence. The omitted values must be shared and distinct; allowing infinity as a subsequential limit is essential. For meromorphic functions the convergence definition must be changed and a three-value condition is different; it is not asserted here from the holomorphic statement. The 1907 bounded proof treats simple connectivity first and then finite-connectivity/covering extension. The 1912 theorem is recorded in its holomorphic setting; modular-function/logarithm lifting must be applied on suitable simply connected subdomains, not assumed globally single-valued on every multiply connected domain. Earlier Arzela/Ascoli, Weierstrass, Stieltjes/Vitali and Picard/Borel/Schottky/Landau inputs remain distinct.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. Convergence is local uniform convergence inside a complex domain, not uniform convergence up to every boundary or convergence of the whole original sequence. The omitted values must be shared and distinct; allowing infinity as a subsequential limit is essential. For meromorphic functions the convergence definition must be changed and a three-value condition is different; it is not asserted here from the holomorphic statement. The 1907 bounded proof treats simple connectivity first and then finite-connectivity/covering extension. The 1912 theorem is recorded in its holomorphic setting; modular-function/logarithm lifting must be applied on suitable simply connected subdomains, not assumed globally single-valued on every multiply connected domain. Earlier Arzela/Ascoli, Weierstrass, Stieltjes/Vitali and Picard/Borel/Schottky/Landau inputs remain distinct.

Contributors

Provisional WRS assessment, edition 2026-10-23.4. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

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