Research
Mathematics
Papers and notes on local-to-global questions.
Names and dates refer to the questions discussed.
Algebraic Topology & Complex Geometry1 paper · 13 notes
Suciu (2001); Aprodu–Farkas–Raicu–Suciu (2024)Chen ranks and resonanceResonance geometry determines stable rational Chen ranks for arrangements and compact Kähler manifolds.
The Chen Ranks Conjecture and Geometric Separation of Resonance in Complex Geometry
This work proves the stable rational-rank form of Suciu’s Chen ranks conjecture (2001) for every complex affine hyperplane arrangement. One of the flagship problems at the intersection of complex algebraic geometry and topology, the conjecture has guided hyperplane arrangement theory for twenty-five years. It relates the stable growth of the fundamental group’s metabelian quotient to the linear components of resonance. For an arrangement of N hyperplanes, the formula holds in every degree q ≥ max{2, N − 1}, improving to q ≥ max{2, N − 2} for nonempty central arrangements.
Geometric separation of resonance extends to smooth connected quasi-projective varieties whose first cohomology is pure of weight two, with an effective range determined by the first Betti number. For every compact connected Kähler manifold, including nonprojective examples, it proves reducedness of the canonical projective resonance scheme and the stable Chen ranks formula, answering Aprodu–Farkas–Raicu–Suciu’s Question 7.3 and proving their Conjecture 7.4 (2024), respectively.
Lean 4 V1 (work in progress) verifies the affine and central arrangement formulas from AFRS’s effective canonical Koszul decomposition as the sole external mathematical input, with no additional project axioms or proof gaps.
Topology of Complex Varieties13 notesNotes on formality, resonance, cohomology, and fundamental-group invariants.
A research program in the topology of complex varieties, centered on formality, resonance, cohomology, and fundamental-group invariants. These thirteen notes give answers and counterexamples to open problems posed between 2007 and 2026.
- Critical Koszul pairings force nonvanishing in infinitely many dimensions, refuting Aprodu–Farkas–Raicu–Suciu’s generic vanishing conjecture (2025). PDF · 12 pp
- Elliptic Koszul structures admit explicit Segre models and linear resolutions, answering Suciu’s Problem 22.8 and proving Conjecture 22.11 (2026). PDF · 10 pp
- Abelian arrangement complements are formal exactly when their distinct normal directions are independent, answering Pagaria’s formality question (2018) and the formality part of Suciu’s Problem 8.3 (2015). PDF · 9 pp
- Clique reconstruction recovers graphic arrangement groups and integral Lie structures, resolving Cohen–Falk’s Problem 5.13 (2019). PDF · 15 pp
- Integral Alexander separation resolves Suciu’s residual nilpotence question for graphic metabelian quotients and yields finite-cover formulas that refute his arbitrary-weight Milnor monodromy questions (2024). PDF · 12 pp
- Exterior annihilators refute Lundqvist–Nicklasson’s odd-factor explanation and homology monotonicity (2018), with a (9, 3) witness for Question 6.3. PDF · 9 pp
- Finite quotients miss group cohomology classes for a five-line arrangement, refuting the goodness questions of Cohen et al. (2009) and Suciu (2026), yet still determining the integral homology of its finite covers. PDF · 12 pp
- Enriched homology shows that Cohen–Macaulay complexes need not have propagating support loci and that identical design parameters can conceal different Betti numbers, answering questions of Aprodu–Farkas–Raicu–Sammartano–Suciu (2023) and Fløystad (2007). PDF · 7 pp
- Integral cyclic-cover cohomology is torsion-free under the CDO condition for essential complex affine arrangement complements, proving Xie’s Conjecture 1.9 (2026); deck representations are computed even in characteristics dividing the covering degree. PDF · 9 pp
- Incidence complexes determine every torsion invariant factor in the first homology of Milnor fiber boundaries of projective line arrangements, answering Némethi–Szilárd’s torsion-formula problem (2011) in this setting and proving all three parts of Sugawara’s Conjecture 1.4 (2025). PDF · 10 pp
- Primitive toric covers have exact counts determined by the layer poset and ambient dimension, answering Delucchi–Marmo’s question (2025) for essential arrangements and establishing positive density in dimension at least two. PDF · 10 pp
- Integral cellular models resolve Delucchi–Pagaria’s general elliptic-arrangement problem (2020), including complex multiplication; extension data give a negative answer to Gorinov–Zakharov’s question about models using only the cohomology of intersections (2026). PDF · 9 pp
- Modular fibrations arise from M-ideals of arbitrary rank, proving Bibby–Delucchi’s conjecture (2022); integral monodromy answers their Question 5.3.8 for admissible rank-one projections and detects shear terms in compact fibers. PDF · 18 pp
Combinatorial Algebra & Discrete Geometry5 papers
Kurosh (1941)Nil algebras and growthOver arbitrary fields, infinite-dimensional finitely generated nil algebras can attain the minimal Gelfand–Kirillov dimension, two.
The Kurosh Problem at Gelfand–Kirillov Dimension Two over Arbitrary Fields
This work addresses the critical boundary of the Kurosh problem under growth restrictions. The construction gives, over every field, an infinite-dimensional 2-generated graded nil algebra of Gelfand–Kirillov dimension 2, the smallest possible growth dimension for such an algebra.
An end-to-end Lean 4 formalization verifies the existence theorem over arbitrary fields, including infinite dimensionality, GK dimension 2, and nilpotence in every matrix size after every field extension.
Jackson–Jordán (2009); Tanigawa (2011)Body–pin rigidityA partition criterion characterizes when generic three-dimensional bodies joined at pins form a rigid structure.
When do pinned bodies become one rigid structure?
A partition criterion resolves the body–pin conjecture, which had been open for nearly two decades. First proposed by Jackson–Jordán in 2009 and independently by Tanigawa in 2011, the criterion characterizes generic Euclidean rigidity through every partition of the bodies, with pin capacities 3, 5, and 6.
A stress-codimension theorem and recursive collinearity flags carry the proof through exceptional configurations. The companion Lean development proves the final maximum-rank equivalence end to end. A companion blueprint by Bryan Chen, a Mathlib maintainer, maps the paper’s argument and its Lean formalization.
Bill Jackson mentioned this work at Lancaster University’s September 2026 rigidity workshop.
Bland–Jensen (1987)Weakly orientable matroidsWeak orientability has infinitely many minimal matroid obstructions, ruling out a finite excluded-minor list.
No finite list can capture every obstruction.
Infinitely Many Excluded Minors for Weakly Orientable Matroids
This work proves the 1987 Bland–Jensen conjecture, which had been open for nearly four decades. Infinitely many pairwise nonisomorphic excluded minors rule out a finite forbidden-minor characterization of weakly orientable matroids.
The family grows in rank and size, but its representability argument takes place in quotient spaces of dimension two or three. Nine parity equations give a uniform obstruction; six rational quotient constructions establish minimality. The Lean formalization follows the chain from signed circuits and cocircuits to the failure of every finite forbidden-minor list.
Dillon Mayhew (University of Leeds) confirmed that the final Lean theorem expresses the intended statement about finite excluded-minor characterizations. On August 14, 2026, Jesús De Loera invited a talk on this work at a small seminar he organized.
Scott–Sokal (2014)Spanning-tree positivityGraph structure and clique gluing connect spanning-tree polynomial positivity with rigidity and analytic obstructions.
Complete Monotonicity of Inverse Powers of Spanning-Tree Polynomials: Positive-Semidefinite Compression, Clique Gluing, and Graph-Family Classification
This work classifies completely monotone inverse powers of spanning-tree polynomials for complete multipartite graphs. It also proves preservation under clique gluing, answering Scott–Sokal’s triangle-gluing question (2014). The cube and octahedron disprove planar-duality invariance for 1 < β < 3/2. Positive-semidefinite stress compression connects these analytic obstructions to universal rigidity.
Averkov–Martini (2008)Translated segmentsThe number of spanning segments determines when determinant bounds on minimum volume are universally sharp.
The universal determinant formula for translated segments
The determinant bound is universally sharp exactly for d or d + 1 spanning segments in dimension d ≥ 2, resolving Averkov–Martini’s Problem 1 (2008).
Matrix Analysis1 paper
Marcus (1973); de Oliveira (1982)The Marcus–de Oliveira conjectureFor 4 × 4 normal matrices, elliptic curves connect unitary minors with determinant convexity.
The Marcus–de Oliveira conjecture for n = 4
This work proves the Marcus–de Oliveira determinantal conjecture for 4 × 4 normal matrices. Proposed independently by Marcus (1973) and de Oliveira (1982), the conjecture asks whether the determinant of a sum of normal matrices lies in the convex hull of eigenvalue pairing products. Four was the first unresolved matrix size after the 1987 theorem for 3 × 3 matrices.
A new structural theorem reproduces the squared moduli of every minor of any 4 × 4 unitary matrix as one common convex mixture of the corresponding data from just two real orthogonal matrices. This simultaneous reduction comes from Gale duality and a real circle in the Picard curve of an elliptic quartic. The determinant problem then passes to the invariants of eight points on the projective line, where the maximum principle on algebraic curves reduces it to finitely many contact configurations.
Dynamics & Kinetic Theory4 papers
McKean (1966); Carlen–Carvalho–Einav (2018); Einav (2023)Entropy propagation and McKean’s conjectureEntropy and entropy production admit uniform particle limits, while higher heat-entropy monotonicity fails at every order ≥ 5.
Uniform-in-Time Entropic Chaos, Entropy Production, and McKean’s 1966 Conjecture for the Kac Master Equation
Within Kac’s programme (1956), this work answers propagation questions of Carlen–Carvalho–Einav (2018) and Einav (2023) for the classical constant-rate, uniform-angle model. From entropically chaotic initial data of finite energy and entropy, entropy per particle converges uniformly for t ≥ 0 and instantaneous entropy production per particle uniformly for t ≥ δ > 0. Fixed-order log-power bounds propagate on bounded time intervals without loss of order.
The work also refutes McKean’s 1966 heat-entropy monotonicity conjecture: for each prescribed order n ≥ 5, a smooth positive density has a higher heat-entropy functional that increases under Kac collisions.
Higher log-power functionals can develop logarithmic-time transient peaks of order √N, even while total relative entropy and total variation distance to equilibrium vanish uniformly in time. This separates macroscopic entropy relaxation from higher-order amplification.
Ghioca–Scanlon (2014)Semiabelian dense orbitsIn characteristic zero, common rational invariants govern dense orbits of arbitrary semigroups on semiabelian varieties.
Zariski Dense Orbits for Arbitrary Semigroups on Semiabelian Varieties
This work answers Ghioca–Scanlon’s arbitrary-monoid extension question (2014). A monoid of dominant regular self-maps on a semiabelian variety over an algebraically closed field of characteristic zero has a Zariski dense orbit exactly when its common rational invariants are constant. The theorem covers noncommuting maps, generating sets of arbitrary cardinality, and nonsplit extensions.
Over a fixed finitely generated field, one algebraic starting point realizes this dichotomy simultaneously for every monoid defined over that field.
Derksen (2005)Recurrence zero setsIn positive characteristic, prescribed p-normal patterns arise exactly as zero sets of finite-order linear recurrences.
Derksen's inverse conjecture on zero sets of linear recurrences
This work resolves Derksen’s inverse conjecture (2005). Every p-normal subset of the nonnegative integers—including negative weights, rational shifts, and finite modifications—is the exact zero set of a finite-order linear recurrence over the fixed field 𝔽p(t), with a Lean 4 formalization of the inverse theorem.
Aoki–Lukkarinen–Spohn (2006)Pinned-chain collision invariantsTwo additive collision invariants determine the conserved fields available for macroscopic closure of a pinned chain.
The spectrum can retain memory even when only two densities are conserved.
Collision invariants and long-lived spectral memory in a one-dimensional pinned chain
This work resolves Aoki–Lukkarinen–Spohn’s collision-invariant conjecture (2006), which had been open for twenty years. For every strictly pinned bandwidth, all measurable additive collision invariants are linear combinations of wave action and energy, determining the two-parameter equilibrium family. This identifies the conserved fields needed for macroscopic closure within the kinetic-theory programme of Hilbert’s sixth problem, with a companion Lean 4 proof of the classification.
Along the narrow-band equilibrium path, a positive linearized spectral gap closes as the band narrows. In linear response, preparations with identical wave action, energy, and initial entropy remain spectrally distinguishable over a diverging time window.
Geometric Analysis7 papers
Brezis (1999)Ginzburg–Landau vortex minimalityIn balls of dimension ≥ 3, profile comparison establishes radial degree-one vortex minimality with identity boundary data.
Profile comparison establishes global minimality for the radial Ginzburg–Landau vortex.
On Brezis’ Open Problem 6: Global Minimality of the Degree-One Ginzburg–Landau Vortex in Balls
Following Chen–Liu–Wei–Yang’s approach, this work develops the finite-ball/entire-space profile comparison in dimensions n ≥ 3. It establishes global minimality and uniqueness of the radial degree-one Ginzburg–Landau vortex in Bn with identity boundary data, for every ε > 0.
A companion Lean 4 formalization follows the higher-dimensional proof from four stated analytic inputs.
Komendarczyk (2008)Adapted contact metricsAdapted metrics connect contact dynamics with curl eigenvalues and the cost of local contact degeneration.
Local contact degeneration has a sharp logarithmic cost.
This work answers Komendarczyk’s Question 2.7 (2008). For a fixed contact form on a closed three-manifold preserved by a locally free circle action, the construction gives an adapted metric making the form a curl eigenform with any prescribed positive eigenvalue while keeping the circle generator unit Killing.
Local contact degeneration has a sharp logarithmic cost. On a base of dimension 2n, the least quadratic Hn+1 deformation cost for flattening the paired curvature on a ball of radius r in time T is comparable to 1 / [T log(R*/r)] for fixed background data. The cost tends to zero as the target ball shrinks, even while contactness persists until the terminal time.
Chakradhar et al. (2025)Magnetic frustrationDegenerating circle-bundle metrics can preserve spectral gaps and flat holonomy even as regions lose volume.
A region can lose its volume while its spectral memory persists.
This work proves the uniform magnetic frustration conjecture of Chakradhar, Gittins, Habib, and Peyerimhoff. Posed in §4.1 of their 2025 Mathematika paper, the conjecture asks whether a magnetic potential that cannot be gauged away has uniformly positive frustration on domains occupying almost all of the manifold with sufficiently small internal boundary. A covariant BV coercivity estimate supplies the bound.
In a specific family of connection metrics on circle bundles, the metric can lose rank while a positive Hodge spectral gap persists uniformly. A region whose limiting volume density vanishes still contributes magnetic Dirichlet-to-Neumann boundary energy to the scalar spectral limit, retaining its flat holonomy—the phase accumulated around loops.
Ziller (2001); Florit–Ziller (2011); Friedman–Park (2016, 2024)Gauge realizationBundle topology creates global obstructions to gauge realization and distinguishes reductions with identical local curvature.
Pointwise symmetry need not admit a global gauge realization.
This work answers questions in Friedman–Park’s 2016 and 2024 papers. It determines the structure group of their diagonalization bundle and the second cohomology of its base, and realizes every integral solution of their three-eigenline equation on S2 × S2.
It also answers Ziller’s Problem 3(a) (2001) negatively and refutes its Florit–Ziller strengthening (2011). The construction produces fully fat bundles over closed hyperbolic four-manifolds whose underlying structure group nevertheless reduces to a circle.
Gauge mirrors test whether pointwise symmetries lift globally. An affine second-Chern charge lattice distinguishes reductions with identical paired curvature, even on a trivial ambient bundle. Finite-order lift spectra detect eigenbundle topology: for isomorphic rank-two eigenblocks, an order-six mirror exists exactly when they split into line bundles.
Mazowiecka et al. (2024); Frank et al. (2025)Spectral collisions and stabilitySpectral collisions retain eigenspace geometry; strong convergence supports stability of minimizing maps into complex projective spaces.
Colliding eigenvalues do not erase their geometry.
This work answers Mazowiecka–Miśkiewicz–Schikorra’s stability question (2024) beyond sphere targets for every ℂPN, under the stated strong convergence assumptions. The paper also proves Frank–Pintér–Varjas–Pályi’s complex-isolation conjecture (2025) for their crystalline four-band pencil.
Spectral incidence retains eigenspaces at collisions, while energy minimization selects persistent tangent models. Smooth three-band fields can share their spectrum and every jet yet differ in diagonalizability.
Fujioka (1993)Minimizing projective conesNonconstant minimizing radial cones in complex projective spaces are classified by projective lines and absolute degree one.
Minimizing cones in complex projective spaces
This note completes Fujioka’s 33-year-old classification problem (1993). In every complex projective space, the nonconstant minimizing radial cones are exactly round projective-line hedgehogs of absolute degree one.
Recorded by Pilca (2012)Maximal Betti rigidityFor closed, connected, oriented geometrically formal manifolds, maximal nontrivial Betti numbers force flat tori and flat formal metrics.
Extremal Exterior Algebra and Maximal Betti Rigidity in Geometric Formality
On a closed, connected, oriented geometrically formal manifold, a maximal Betti number in any nontrivial degree forces a flat torus and flatness of every formal metric, resolving the higher-degree conjecture recorded by Pilca (2012).