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Sekhar Babu Gosala

Publications and source records attributed to Sekhar Babu Gosala.

3 recordsLinked to original sources

Morita Transport, Marked Projective Loci, and Dedekind Classification for C4-Type Conditionss

Objectwise Morita invariance of $\Cfour$ is known. We prove the corresponding statements for $\Cfourstar$, semi-weak-CS, and strongly $\Cfourstar$, including the chain joins in the definition of semi-weak-CS. For a module property $\mathcal Q$ preserved and reflected by equivalences, we consider the subset $\Vmon_{\mathcal Q}(R)$ of the finitely generated projective monoid $\Vmon(R)$. This marked pair is transported by Morita equivalence. The associated regular-module ring property is Morita invariant if and only if membership in $\Vmon_{\mathcal Q}(R)$ is constant on the order units. The matrix profile satisfies $μ_{\mathcal Q}(M_m(R))=\{n\geq1:mn\inμ_{\mathcal Q}(R)\}$. For a nondivision right Ore domain, the profiles of $\Cfour$, $\Cfourstar$, and strongly $\Cfourstar$ are $\{1\}$, whereas the semi-weak-CS profile is $\mathbb N_{\geq1}$. Over a nonfield Dedekind domain $D$, the first three marked loci consist of the projectives of rank at most one, while every finitely generated projective is semi-weak-CS. For a finitely generated $D$-module $M$, we prove that every $\Cfour$ defect at rank at most one can be transferred between $M$ and $τ(M)$, and we construct a defect when the rank is at least two. Hence $M$ is $\Cfour$ if and only if $\operatorname{rank}_D M\leq1$ and $τ(M)$ is $\Cfour$; the analogous criterion holds for $\Cfourstar$. Combined with the finite-length torsion criterion, these reductions give invariant-factor tests for the four conditions and criteria for their behaviour under direct sums.

math.RA↗

Finite diagonalizable torsors and Kummer cohomology over semiring schemes

Classical descent treats a finite diagonalizable torsor as a higher-rank locally free object. Over semirings that route is incomplete: fpqc-local freeness is not known to imply Zariski-local freeness in arbitrary rank. We show that diagonalizable symmetry bypasses this obstruction. The coordinate semialgebra splits into character pieces, each piece descends in rank one, and the torsor identity makes their multiplication maps invertible. This gives a natural equivalence between fpqc \(D_X(Q)\)-torsors and Picard-strong \(Q\)-gradings, and represents every torsor by a finite locally free morphism of rank \(|Q|\). The same viewpoint proves that finite-index monomial maps of split tori are finite locally free torsors and yields matrix Kummer classification sequences. A concrete example is the nontrivial Boolean torsor \(\Spec\mathbb B[v^{\pm1}]\to\Spec\mathbb B[u^{\pm1}]\), \(u\mapsto v^m\), whose unit-power classes contribute \(\mathbb Z/m\mathbb Z\) to degree-one cohomology. A two-term resolution of the character group then gives a presentation-independent universal-coefficient filtration for diagonalizable fpqc cohomology. This formalism organizes, but does not compute, \(\mathbf G_{\mathrm m}\)-cohomology. In degree two it identifies the Kummer boundary of a line bundle with its root gerbe. On projective space over the Boolean or real tropical semifield all \(μ_m\)-torsors vanish, whereas the root gerbe of \(\mathcal O(1)\) has exact order \(m\). Thus torsors and gerbes retain information that can disappear under ordinary ring completion.

math.RA↗

Finite-sample certification and operating envelopes for spectral clustering and graph centrality

Spectral clustering and node rankings are commonly reported from one observed network without a finite-sample statement of what the observation supports. We develop a certification protocol that either returns a coverage-guaranteed set or explicitly returns ``no nontrivial certificate.'' For an inhomogeneous Bernoulli graph, a matrix-Bernstein quantile with all numerical constants and its ambient-dimension factor retained is combined with a one-sided spectral-gap certificate. The resulting Grassmann ball is valid at finite \(n\), but is reported as informative only when its radius is below the diameter of the Grassmannian. We propagate the ball through a certificate-bearing approximate \(k\)-means map under declared population separation and minimum-cluster envelopes, derive simultaneous bands and an observed-gap certificate for degree centrality, and give a corrected normalized-Katz extension. A \(12\)-cell simulation study with \(1{,}000\) graphs per cell maps the difference between coverage and usefulness. The submitted \(n=200\) block-model example is shown to be necessarily vacuous after the dimension factor is restored; in the benchmark \(p=0.30,q=0.10\), the subspace radius first falls below one at \(n=\ExactRadiusThreshold\), whereas the mean-square clustering certificate remains unavailable until \(n=\HammingThreshold\). An unequal-block example produces a genuine centrality certificate, while an analysis of the Zachary karate-club network correctly declines to certify despite \(97.1\%\) agreement with the observed factions. These results separate algorithmic success, coverage validity and inferential informativeness.

math.ST↗