Reverse Brunn-Minkowski constant ()
Reverse Brunn-Minkowski constant: determine or improve its bounds; the repository records 1 (lower) and (upper).
Editorial MSC2020 classification. Original article codes and source evidence are recorded in the literature directory.
Problem statement
For subsets , their Minkowski sum is
In general, one cannot expect a reverse Brunn-Minkowski inequality for arbitrary compact sets, even with a fixed multiplicative constant. [Bas1995-no-general-reverse]
Milman's reverse Brunn-Minkowski theorem says that for centrally symmetric convex bodies, after putting the bodies in a suitable relative position, one does get a dimension-free reverse inequality. [Bas1995-milman-statement]
More precisely, define as the infimum of constants such that for every and every pair of centrally symmetric convex bodies , there exists a linear map with satisfying
We define
the reverse Brunn-Minkowski constant.
Milman's theorem implies . [Bas1995-milman-statement]
A trivial lower bound is .
Thus the best established range currently is
Lean 4
No Lean statement or proof is attached yet. Have a formalization? Share its source to add it to this problem.
Background
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Original source. The reverse inequality was introduced by Milman in 1986. [Mil1986]
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Proof history. Bastero-Bernues-Pena explicitly record that Pisier (1989) and Milman (1988) gave alternative proofs of Milman's theorem. [Bas1995-proof-history]
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Published extension. Bastero-Bernues-Pena prove a broader affine-invariant reverse inequality for bodies with (with constant depending only on ). [Bas1995-extension-theorem1]
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Wikipedia page on Milman's reverse Brunn-Minkowski inequality
References (from the repository page)
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[Bas1995] Bastero, J.; Bernues, J.; Pena, A. An extension of Milman's reverse Brunn-Minkowski inequality. Geometric and Functional Analysis 5 (1995), no. 3, 572-581. DOI: https://doi.org/10.1007/BF01895832. Publisher page: https://link.springer.com/article/10.1007/BF01895832. arXiv PDF: https://arxiv.org/pdf/math/9501210.pdf. Google Scholar
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[Bas1995-no-general-reverse] loc: arXiv PDF p.1, Introduction quote: "It is easy to see that one cannot expect the reverse inequality to hold at all, even if it is perturbed by a fixed constant and we restrict ourselves to balls..."
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[Bas1995-milman-statement] loc: arXiv PDF p.1, Introduction (quoted Milman theorem statement) quote: "There exists a constant such that for all and any balls we can find a linear transformation with and ."
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[Bas1995-proof-history] loc: arXiv PDF p.1, Introduction quote: "Pisier in [Pi 2] gave a new proof by using interpolation and entropy estimates. Milman in [Mil 2] gave another proof by using the 'convex surgery' and achieving also some entropy estimates."
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[Bas1995-extension-theorem1] loc: arXiv PDF p.1, Theorem 1 quote: "Let . There exists such that for all and all bodies such that , there exists an affine transformation ... such that ."
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[Mil1986] Milman, V. D. Inegalite de Brunn-Minkowsky inverse et applications a la theorie locale des espaces normes. C. R. Acad. Sci. Paris, Serie I 302 (1986), 25-28. MR: 0827101. Google Scholar
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[Mil1988] Milman, V. D. Isomorphic symmetrization and geometric inequalities. In Geometric Aspects of Functional Analysis (1986/87), Lecture Notes in Mathematics 1317 (1988), 107-131. DOI: https://doi.org/10.1007/BFb0081738. Google Scholar
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[Pis1989] Pisier, Gilles. The Volume of Convex Bodies and Banach Space Geometry. Cambridge Tracts in Mathematics, vol. 94, Cambridge University Press (1989). DOI: https://doi.org/10.1017/CBO9780511662454. Google Scholar
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[Pis1989b] Pisier, Gilles. A new approach to several results of V. Milman. Journal fur die reine und angewandte Mathematik 393 (1989), 115-131. DOI: https://doi.org/10.1515/crll.1989.393.115. Google Scholar
Progress & source assessment
Repository table (commit 2c1968c, 26 September 2026): best known lower bound 1; best known upper bound . Values marked with an asterisk have minimal verification.
Known upper bounds
| Bound | Reference | Comments |
|---|---|---|
| [Mil1986], [Bas1995] | Existence of a dimension-free constant in Milman's theorem. [Bas1995-milman-statement] |
Known lower bounds
| Bound | Reference | Comments |
|---|---|---|
| Trivial scaling lower bound. |
- [1]Davis, Damek; Ivanisvili, Paata; Tao, Terence (maintainers). Optimization Constants in Mathematics, github.com/teorth/optimizationproblems (commit 2c1968c, 26 September 2026). — Reverse Brunn-Minkowski constant ($C_{70}$) linkApache-2.0 (repository license); constant pages reproduced with attribution; repository references retained.
Recorded progress
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