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arxiv: 2401.06680 · v2 · submitted 2024-01-12 · 🧮 math.AT

LS-category and topological complexity of real torus manifolds and Dold manifolds of real torus type

Pith reviewed 2026-05-24 04:09 UTC · model grok-4.3

classification 🧮 math.AT
keywords LS-categorytopological complexityreal torus manifoldsDold manifoldssmall coversequivariant LS-categorysymmetric topological complexitygeneralized real Bott manifolds
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The pith

Under certain hypotheses, the topological complexity of real torus manifolds of dimension n is either 2n or 2n+1.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper computes the LS-category of real torus manifolds, which generalize small covers, and of Dold manifolds of real torus type, which are fiber bundles over projective product spaces. It derives sharp bounds on topological complexity and proves that qualifying n-dimensional real torus manifolds have topological complexity exactly 2n or 2n+1. Tight bounds are given for generalized real Bott manifolds, with the gap often less than 5. The work also yields the Z2-equivariant LS-category for small covers whose fixed points are path-connected and exact symmetric topological complexity values for infinitely many of the manifolds considered.

Core claim

The real torus manifolds are a generalization of small covers, and the Dold manifolds of real torus type are a class of non-trivial fibre bundles over the projective product spaces with real torus manifolds as fibres. We compute the LS-category of these two types of manifolds and obtain sharp bounds on their topological complexities. We show that under certain hypotheses, the topological complexities of real torus manifolds of dimension n are either 2n or 2n+1. We figure out tight bounds for the topological complexity of generalized real Bott manifolds, and in many cases, the difference between these upper and lower bounds is less than 5. We compute the Z2-equivariant LS-category of small 0.

What carries the argument

The structural definitions of real torus manifolds as generalizations of small covers together with the fiber-bundle construction of Dold manifolds of real torus type, used under hypotheses such as path-connectedness of Z2-fixed point sets to bound LS-category and topological complexity.

If this is right

  • Topological complexity of qualifying real torus manifolds takes only the two values 2n and 2n+1.
  • Upper and lower bounds on topological complexity for generalized real Bott manifolds differ by less than 5 in many cases.
  • The Z2-equivariant LS-category equals a specific value for small covers whose Z2-fixed points form a path-connected set.
  • Symmetric topological complexity attains exact computed values for infinitely many of the manifolds studied.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same bundle and fixed-point techniques could be applied to compute topological complexity for other classes of manifolds equipped with involutions or torus actions.
  • The narrow gap between bounds for generalized real Bott manifolds indicates that additional algebraic invariants might close the gap to exact values.
  • Exact symmetric topological complexity results supply concrete test cases for comparing symmetric and ordinary topological complexity on the same spaces.

Load-bearing premise

The manifolds satisfy the structural definitions of real torus manifolds or Dold manifolds of real torus type and the stated hypotheses including path-connectedness of the Z2-fixed points hold.

What would settle it

A single real torus manifold of dimension n whose topological complexity is measured to be neither 2n nor 2n+1 would falsify the stated claim.

read the original abstract

The real torus manifolds are a generalization of small covers, and the Dold manifolds of real torus type are a class of non-trivial fibre bundles over the projective product spaces with real torus manifolds as fibres. In this paper, first, we compute the LS-category of these two types of manifolds and obtain sharp bounds on their topological complexities. We show that under certain hypotheses, the topological complexities of real torus manifolds of dimension $n$ are either $2n$ or $2n+1$.We figure out tight bounds for the topological complexity of generalized real Bott manifolds, and in many cases, the difference between these upper and lower bounds is less than 5. We compute the $\mathbb{Z}_2$-equivariant LS-category of small covers when the $\mathbb{Z}_2$-fixed points are path connected. In the end, we study the symmetric topological complexity of the above-mentioned manifolds and obtain exact values for infinitely many cases.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The manuscript computes the LS-category of real torus manifolds and Dold manifolds of real torus type. It obtains sharp bounds on their topological complexities, showing that under certain hypotheses the topological complexities of real torus manifolds of dimension n are either 2n or 2n+1. It provides tight bounds for the topological complexity of generalized real Bott manifolds, with the difference between upper and lower bounds less than 5 in many cases. It computes the Z_2-equivariant LS-category of small covers when the Z_2-fixed points are path connected. Finally, it studies the symmetric topological complexity of these manifolds and obtains exact values for infinitely many cases.

Significance. If the results hold, they contribute concrete computations and bounds for LS-category and TC on these classes of manifolds, including equivariant and symmetric variants, with exact values in infinitely many cases. This adds to the body of explicit results in the area.

major comments (1)
  1. The abstract asserts the existence of computations and bounds, but without the full proofs or methods it is impossible to check whether the derivations actually support the stated claims; major verification gap.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and positive summary of the manuscript. We address the single major comment below.

read point-by-point responses
  1. Referee: The abstract asserts the existence of computations and bounds, but without the full proofs or methods it is impossible to check whether the derivations actually support the stated claims; major verification gap.

    Authors: The full manuscript contains the complete proofs and methods. The LS-category computations for real torus manifolds appear in Section 3, those for Dold manifolds of real torus type in Section 4; the sharp TC bounds for real torus manifolds (showing values 2n or 2n+1 under the stated hypotheses) are proved in Section 5; tight bounds for generalized real Bott manifolds are derived in Section 6; the Z_2-equivariant LS-category result for small covers with path-connected fixed-point set is established in Section 7; and the exact symmetric TC values for infinitely many cases are obtained in Section 8. All derivations rely on standard tools from algebraic topology (cup-length lower bounds, sectional category upper bounds via fibrations, and equivariant methods) applied to the explicit cell structures and cohomology rings of these manifolds. The referee is referred to these sections for verification; we are prepared to expand any specific step if requested. revision: no

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The provided abstract and context describe standard computations of LS-category and topological complexity for real torus manifolds and Dold manifolds, yielding bounds such as 2n or 2n+1 under stated hypotheses. No equations, definitions, or self-citations are supplied that reduce any claimed result to a fitted input, self-definition, or load-bearing prior work by the same authors. The derivation chain appears self-contained against external topological definitions and is not forced by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

No free parameters or invented entities are visible from the abstract; the work rests on standard properties of LS-category and topological complexity.

axioms (1)
  • standard math Standard properties of LS-category and topological complexity as homotopy invariants
    Computations rely on established definitions and properties of these invariants from algebraic topology.

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Reference graph

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