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Casson–Gordon invariants and sliceness obstructions

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1 · Prerequisites
2 · Logical flowchart

3 · Items

Definition

Bounding-chain expression for a torsion linking pairing

Definition

Finite nonsingular linking forms and metabolizers

Definition

Oriented bordism groups of maps to a space

Definition

Poly-torsion-free abelian groups

Lemma

Local-coefficient cap duality on a coordinate ball without choice

Lemma

Choice-free Wall chain finiteness from an explicit finite domination

Lemma

Compact manifold fundamental groups have finite generators without choice

Lemma

A compact manifold's twisted singular chains admit a one-vertex reduction without choice

Lemma

Compact-support local Mayer–Vietoris and its cap ladder without choice

Lemma

Finite-order smooth line bundles have torsion reduced bundle class

Lemma

Finite von Neumann modules, Hilbert closures, and dimension-zero quotients

Lemma

Finite torsion-free abelian freeness by explicit rational coordinates without choice

Lemma

Finite Folner sets give both Ore conditions and a constructed skew field of fractions

Theorem

Compact manifolds are retracts of finite polyhedra without choice

Theorem

Explicit mitoses give functorial integrally acyclic group envelopes

Definition

Exterior of a smooth proper disk

Lemma

Finite smooth surface presentations admit prescribed collar matches

Lemma

Finite cellular L2 duality and weak exactness

Lemma

The torsion linking pairing of a rational homology sphere is nonsingular

Lemma

Oriented bordism classes over a space form an abelian group

Lemma

PTFA groups satisfy the finite Folner condition without a choice hypothesis

Lemma

Nonsplit torsion-free abelian extensions preserve absence of group-ring zero divisors

Lemma

Von Neumann inertia, dense congruences, and coisotropic reduction

Theorem

Compact oriented manifold duality with local coefficients without choice

Theorem

Compact twisted signature operators give additive bundle indices and finite-character signatures

Theorem

Compact-support duality for finite-atlas manifolds without choice

Theorem

Finite geometric chains and compact manifold chain domination without choice

Definition

Zero-framed surgery on a knot

Lemma

Twisted right-chain duals realize local coefficient duality

Lemma

Integral and field PTFA group rings have compatible Ore fractions and involutions

Lemma

The boundary kernel of a rational homology ball is a linking metabolizer

Lemma

The exterior of a smooth proper disk has the homology of a circle

Theorem

The relevant third oriented bordism group is finite

Theorem

Local coefficient Lefschetz duality without choice

Theorem

PTFA group rings embed in skew fields of fractions

Definition

Infinite and finite cyclic covers of a slice-disk exterior

Lemma

Equivariant intersections under collared bordism gluing

Lemma

Disk-band Seifert surfaces give actual cyclic zero-surgery bounding manifolds

Lemma

Hermitian symmetry of the relative equivariant intersection pairing

Lemma

Prime-power cyclic covers of a slice-disk exterior over the defining field

Theorem

Topological finite-projective L2 duality and whole-component boundary gluing

Definition

Cyclic cover of zero surgery on a knot

Definition

Finite-order characters of a cyclic branched cover

Definition

Integral half-solutions, Strebel classes, and L²-signatures

Definition

Cyclic branched cover of a smooth proper disk

Theorem

Topological five-dimensional bordisms preserve ordinary and L2 signatures

Definition

Localized Blanchfield pairings and higher-order rho-invariants

Lemma

Finite cyclic von Neumann signatures are exact character averages

Lemma

A prime-power branched cover of a smooth proper disk is a rational homology ball

Lemma

Signature additivity under gluing

Lemma

Homology splitting for the cyclic cover of zero surgery

Theorem

Smooth group signature defects are independent and uniformly bounded

Definition

Torsion linking form and Casson–Gordon bordism data

Lemma

A slice disk induces a metabolizer on the branched-cover linking form

Theorem

Canonical finite cyclic knot signature defects equal Seifert signature averages

Lemma

Prime-power characters admit a multiple bounding bordism

Lemma

Characters vanishing on the disk metabolizer extend over the branched cover

Theorem

Finite cyclic smooth bounding signature defects are independent

Lemma

Nonsingularity of the Casson–Gordon twisted intersection form

Lemma

Bordism independence of the Casson–Gordon Witt class

Definition

Casson–Gordon Witt class and signature defect

Lemma

Casson–Gordon signature defects vanish on the slice metabolizer

Lemma

Prime-power cyclic branched covers of knots have finite first homology

Theorem

Casson–Gordon signature-defect obstruction to sliceness

Sources