Skip to content

From the Obsidian Second Brain

Follow the connections.

146 public records, 14 topic maps, and six reading routes. Select an area, find a paper, or follow a documented reference. The topic hubs follow the layout of the vault’s Research Map.

PaperLarge circles: topics · lines: topic membership32 records shown
6Algebra and algebraicgeometry22Banach spaces andBanach lattices9Combinatorics and Ramseytheory9Geometric group theory7Groupoids and Cartanpairs46Homological algebra andderived limits1Ideals and convergence7Lattices and orderedalgebra10Measure and ergodictheory8Model theory anddefinability32Operator algebras16Ordered groups40Polish groups anddescriptive complexity33Topological dynamics andamenabilityFinite configurations and nuclear quotients of Thompson's group FCharmenability of Thompson's group FNonmeagre ideals from traces on corona algebrasLocal units and multiplier algebras of AF corona idealsThe noncommutative weak extension principle under OCALipschitz positive decompositions of von Neumann predualsIsometric canonical maps into free convex Banach latticesCompletely positive coordinates for KK-theory and relative uniform stabilityPolarities, voltages, and capacitors: a categorical approach to hulls, envelopes, and completionsLipschitz embeddings of symmetric operator-ideal balls into Hilbert spaceA universal Banach–Mazur stability radius for von Neumann algebrasRecursive classification and admissible descent for preliminary C*-algebras with prescribed weighted spectrumSpectral ranks and dynamical lengths of preliminary C*-algebrasA counterexample to the Global Glimm ProblemDynamical spectra of unital C*-algebras: AF realizations and Cartan pairsDynamical length of Cartan pairs: comparison, rigidity, and invarianceSolution to Dixmier's Problem about spectra of C*-algebrasAutomatic equivariant Jiang–Su stability in the nonunital tracial settingPolishability from orbit reducibility of coset equivalence relationsUCT-universal nuclear quotients of a binary wreath productUniversal minimal flows of automorphism groups\\of stable Kirchberg algebrasUniversal minimal flows for unital Kirchberg and AF algebrasA counterexample to the (approximate) Universal Coefficient Theorem for \texorpdfstring{$K$}{K}-homology of C*-algebrasExtreme amenability of the automorphism group of the Jiang-Su algebraExtreme amenability of the automorphism group of the Razak-Jacelon algebraUniversal minimal flows of Cuntz automorphism and unitary groupsDescriptive classification of classes of C*-algebras and locally compact groupsDynamical spectra of separable unital scattered $C^*$-algebras and Cartan pairsNormalizer correction and relative derivation and automorphism lengths for Cartan C*-subalgebrasDerivation length and automorphism length of unital C*-algebrasC*-algebras of all successor ordinal derivation and automorphism lengthsBratteli graphs

Positions aid navigation; distance does not measure mathematical similarity. References were captured in the vault and are not proof dependencies.

Six routes through the archive

Read across the boundaries.

These are proposed syntheses from the Second Brain, not new results or established proof dependencies. Only papers already present in this public catalog are linked here.

Proposed reading route

Classification beyond fixed invariants

The fixed-invariant manuscript constructs E₀ classification inside families sharing a full Elliott invariant and comparison radius. The trace-dynamics manuscript codes homeomorphism conjugacy into cocycle conjugacy. Both illustrate the role of descriptive complexity after familiar invariants have been fixed.

Keep separate: E₀ bireducibility, universality for Polish group orbit relations, and failure of classification by countable structures are distinct claims. Fixed first-order theory is an additional assertion in the fixed-invariant family, not a consequence of every Borel coding.

2 additional source notes are outside this catalog edition.

Proposed reading route

Dynamical lengths, spectra, and Cartan pairs

The Cartan-pair draft organizes five length coordinates and their invariance properties. The AF-spectrum draft classifies realizable values and explicitly imports an exclusion theorem from a companion. The primitive-ideal and Fell–Pedersen drafts examine how topological and rank data constrain dynamical lengths.

Keep separate: Track absolute algebra invariants, pair invariants, and groupoid invariants separately. The Cartan abstract identifies a low-complexity case in which the twist can affect one coordinate. The earlier Fell/Pedersen rank paper and its dynamical-length companion have separate identities.

2 additional source notes are outside this catalog edition.

Proposed reading route

Ideals, bases, and reconstruction

The critical-ideal manuscript constructs ideals from errors of basis expansions. The convergence manuscript builds Polishable groups from ideals. The reconstruction paper asks what those groups remember about the starting ideal.

Keep separate: Keep equality, isomorphism of ideals, Rudin–Blass comparisons, and Katětov equivalence separate. The critical-ideal result up to isomorphism and the reconstruction result up to Katětov equivalence answer different questions.

2 additional source notes are outside this catalog edition.

Proposed reading route

Positive identities and order extension

These drafts connect positivity constraints with algebraic and algorithmic structure. The positive-normal-identity draft states undecidability in fixed free groups; the universal-subgroup draft transfers bi-order extension problems; the common-multiple draft gives a positive theorem for abelian-by-nilpotent groups.

Keep separate: The common-multiple theorem concerns nilpotent coefficient groups and nonnegative coefficients. It does not supply an algorithm for the free-group problems. Arithmetic interpretation in free lattice-ordered groups is another kind of definability statement.

2 additional source notes are outside this catalog edition.

Proposed reading route

Symmetry, concentration, and boundedness

The library contains concentration and Lévy stabilizer constructions, formulas for universal minimal flows, automatic continuity for a homogeneous poset, and a separate collection on quantitative boundedness of Polish groups. Their shared objects are symmetry groups with additional topological or metric structure.

Keep separate: Distinguish amenability, extreme amenability, whirly amenability, concentration, and Property (OB). Record the topology and whether an assertion concerns arbitrary abstract homomorphisms or only continuous actions.

Proposed reading route

Uniform lifting and perturbation

The completely positive correction draft controls a correction using a uniform defect. The recursive-subhomogeneous stability draft states a control function independent of pullback length and matrix sizes. The Banach-lattice semiprojectivity draft formulates almost contractive lifting through ideal quotients.

Keep separate: These are comparisons of proof organization across different categories. A Banach-lattice homomorphism and a C*-algebra *-homomorphism satisfy different requirements. Separate fixed parameters, uniform constants, and dependencies on domain or target.

1 additional source note is outside this catalog edition.

Source: uploaded Second Brain, checked 5 November 2026. 149 vault notes match the 146 public records; version duplicates are consolidated. Personal notes, local paths, and private manuscript links are not included.