Abstract
The composition operators preserving total non-negativity and total positivity for various classes of kernels are classified, following three themes. Letting a function act by post composition on kernels with arbitrary domains, it is shown that such a composition operator maps the set of totally non-negative kernels to itself if and only if the function is constant or linear, or just linear if it preserves total positivity. Symmetric kernels are also discussed, with a similar outcome. These classification results are a byproduct of two matrix-completion results and the second theme: an extension of A. M. Whitney’s density theorem from finite domains to subsets of the real line. This extension is derived via a discrete convolution with modulated Gaussian kernels. The third theme consists of analyzing, with tools from harmonic analysis, the preservers of several families of totally non-negative and totally positive kernels with additional structure: continuous Hankel kernels on an interval, Pólya frequency functions, and Pólya frequency sequences. The rigid structure of post-composition transforms of totally positive kernels acting on infinite sets is obtained by combining several specialized situations settled in our present and earlier works.
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References
M. Aissen, A. Edrei, I. J. Schoenberg and A. M. Whitney, On the generating functions of totally positive sequences, Proc. Natl. Acad. Sci. USA 37 (1951), 303–307.
N. I. Akhiezer, The Classical Moment Problem and Some Related Questions in Analysis, Hafner Publishing, New York, 1965.
T. Ando, Totally positive matrices, Linear Algebra Appl. 90 (1987), 165–219.
Z. D. Bai and L.X. Zhang, Semicircle law for Hadamard products, SIAM J. Matrix Anal. Appl. 29 (2007), 473–495.
S. Banach, Sur l’équation fonctionelle f(x + y)= f(x)+f(y), Fund. Math. 1 (1920), 123–124.
A. Belton, D. Guillot, A. Khare and M. Putinar, Matrix positivity preservers in fixed dimension. I, Adv. Math. 298 (2016), 325–368.
A. Belton, D. Guillot, A. Khare and M. Putinar, A panorama of positivity. Part I: Dimension free, in Analysis of Operators on Function Spaces, Birkhäuser/Springer, Cham, 2019, pp. 117–165.
A. Belton, D. Guillot, A. Khare and M. Putinar, A panorama of positivity. Part II: Fixed dimension, Complex Analysis and Spectral Theory, American Mathematical Society, Providence, RI, 2020, pp. 109–150.
A. Belton, D. Guillot, A. Khare and M. Putinar, Moment-sequence transforms, J. Eur. Math. Soc. (JEMS) 24 (2022), 3109–3160.
A. Belton, D. Guillot, A. Khare and M. Putinar, Hirschman—Widder densities, Appl. Comput. Harmon. Anal. 60 (2022), 396–425.
A. Berenstein, S. Fomin and A. Zelevinsky, Parametrizations of canonical bases and totally positive matrices, Adv. Math. 122 (1996), 49–149.
S. Bernstein, Sur les fonctions absolument monotones, Acta Math. 52 (1929), 1–66.
P. Billingsley, Probability and Measure, John Wiley & Sons, New York, 1995.
S. Bochner, Hilbert distances and positive definite functions, Ann. of Math. (2) 42 (1941), 647–656.
F. Brenti, Unimodal, Log-concave, and Pólya Frequency Sequences in Combinatorics, American Mathematical Society, Providence, RI, 1989.
F. Brenti, Combinatorics and total positivity, J. Combin. Theory Ser. A 71 (1995), 175–218.
B. Efron, Increasing properties of Pólya frequency functions, Ann. Math. Statist. 36 (1965), 272–279.
S. Fallat and C. R. Johnson, Totally Nonnegative Matrices, Princeton University Press, Princeton, NJ, 2011.
S. Fallat, C. R. Johnson and R. L. Smith, The general totally positive matrix completion problem with few unspecified entries, Electron. J. Linear Algebra 7 (2000), 1–20.
S. Fallat, C. R. Johnson and A. D. Sokal, Total positivity of sums, Hadamard products and Hadamard powers: Results and counterexamples, Linear Algebra Appl. 520 (2017), 242–259; Corrigendum, Linear Algebra Appl. 613 (2021), 393–396.
M. Fekete, Über ein Problem von Laguerre, Rend. Circ. Mat. Palermo 34 (1912), 89–120.
C. H. FitzGerald and R. A. Horn, On fractional Hadamard powers of positive definite matrices, J. Math. Anal. Appl. 61 (1977), 633–642.
S. Fomin and A. Zelevinsky, Double Bruhat cells and total positivity, J. Amer. Math. Soc. 12 (1999), 335–380.
S. Fomin and A. Zelevinsky, Total positivity: tests and parametrizations, Math. Intelligencer 22 (2000), 23–33.
F. R. Gantmacher, The Theory of Matrices. Vols. 1, 2, Chelsea Publishing, New York, 1959.
F. R. Gantmacher and M. G. Krein, Sur les matrices complètement non negatives et oscillatoires, Compositio Math. 4 (1937), 445–476.
F. R. Gantmacher and M. G. Krein, Oscillation Matrices and Kernels and Small Vibrations of Mechanical Systems, Chelsea Publishing, New York, 2002.
M. Gasca and C. A. Micchelli, Total Positivity and its Applications, Springer, Dordrecht, 1996.
K. Gröchenig, J. L. Romero and J. Stöckler, Sampling theorems for shift-invariant spaces, Gabor frames, and totally positive functions, Invent. Math. 211 (2018), 1119–1148.
D. Guillot, A. Khare and B. Rajaratnam, Critical exponents of graphs, J. Combin. Theory Ser. A 139 (2016), 30–58.
D. Guillot, A. Khare and B. Rajaratnam, Preserving positivity for rank-constrained matrices, Trans. Amer. Math. Soc. 369 (2017), 6105–6145.
H. Hamburger, Bemerkungen zu einer Fragestellung des Herrn Pólya, Math. Z. 7 (1920), 302–322.
H. Helson, J.-P. Kahane, Y. Katznelson and W. Rudin, The functions which operate on Fourier transforms, Acta Math. 102 (1959), 135–157.
I. I. Hirschman and D. V. Widder, The inversion of a general class of convolution transforms, Trans. Amer. Math. Soc. 66 (1949), 135–201.
I. I. Hirschman and D. V. Widder, The Convolution Transform, Princeton University Press, Princeton, NJ, 1955.
R. A. Horn. The theory of infinitely divisible matrices and kernels, Trans. Amer. Math. Soc. 136 (1969), 269–286.
R. A. Horn, Infinitely divisible positive definite sequences, Trans. Amer. Math. Soc. 136 (1969), 287–303.
T. Jain, Hadamard powers of some positive matrices, Linear Algebra Appl. 528 (2017), 147–158.
C. R. Johnson and O. Walch, Critical exponents: old and new, Electron. J. Linear Algebra 25 (2012), 72–83.
S. Karlin, Total Positivity. Volume 1, Stanford University Press, Stanford, CA, 1968.
A. Khare and T. Tao, On the sign patterns of entrywise positivity preservers in fixed dimension, Amer. J. Math. 143 (2021), 1863–1929.
J. S. Kim and F. Proschan, Total positivity, in Encyclopedia of Statistical Sciences, John Wiley & Sons, New York, 2006, pp. 8665–8672.
Y. Kodama and L. K. Williams, KP solitons, total positivity and cluster algebras, Proc. Natl. Acad. Sci. USA 108 (2011), 8984–8989.
Y. Kodama and L. K. Williams, KP solitons and total positivity for the Grassmannian, Invent. Math. 198 (2014), 637–699.
G. Lusztig, Total positivity in reductive groups, in Lie Theory and Geometry, Birkhäuser, Boston, MA, 1994, pp. 531–568.
G. Lusztig, Total positivity and canonical bases, in Algebraic Groups and Lie Groups, Cambridge University Press, Cambridge, 1997, pp. 281–295.
E. Maló, Note sur les équations algébriques dont toutes les racines sont réelles, J. Math. Spéc. 4 (1895), 7–10.
A. Pinkus, Totally Positive Matrices, Cambridge University Press, Cambridge, 2010.
G. Pólya and I. Schur, Über zwei Arten von Faktorenfolgen in der Theorie der algebraischen Gleichungen, J. reine angew. Math. 144 (1914), 89–113.
A. Postnikov, Total positivity, Grassmannians, and networks, arXiv:math/0609764 [math.CO]
K. Rietsch, Totally positive Toeplitz matrices and quantum cohomology of partial flag varieties, J. Amer. Math. Soc. 16 (2003), 363–392.
A. W. Roberts and D. E. Varberg, Convex Functions, Academic Press, New York—London, 1973.
A. J. Rothman, E. Levina and J. Zhu, Generalized thresholding of large covariance matrices, J. Amer. Statist. Assoc. 104 (2009), 177–186.
K. Schmudgen, The Moment Problem, Springer, Cham, 2017.
I. J. Schoenberg, Positive definite functions on spheres, Duke Math. J. 9 (1942), 96–108.
I. J. Schoenberg, On totally positive functions, Laplace integrals and entire functions of the Laguerre—Pólya—Schur type, Proc. Natl. Acad. Sci. USA 33 (1947), 11–17.
I. J. Schoenberg, On Pólya frequency functions. II. Variation-diminishing integral operators of the convolution type, Acta Sci. Math. (Szeged) 12 (1950), 97–106.
I. J. Schoenberg, On Pólya frequency functions. I. The totally positive functions and their Laplace transforms, J. Anal. Math. 1 (1951), 331–374.
I.J. Schoenberg and A. M. Whitney, On Pólya frequency functions. III. The positivity of translation determinants with an application to the interpolation problem by spline curves, Trans. Amer. Math. Soc. 74 (1953), 246–259.
J. Schur, Bemerkungen zur Theorie der beschränkten Bilinearformen mit unendlich vielen Vera’nderlichen, J. reine angew. Math. 140 (1911), 1–28.
J. A. Shohat and J. D. Tamarkin, The Problem of Moments, American Mathematical Society, New York, 1943.
W. Sierpińsky, Sur l’équation fonctionelle f(x + y)= f(x)+ f(y), Fund. Math. 1 (1920), 116–122.
H. L. Vasudeva, Positive definite matrices and absolutely monotonic functions. Indian J. Pure Appl. Math. 10 (1979), 854–858.
D. G. Wagner, Total positivity of Hadamard products, J. Math. Anal. Appl. 163 (1992), 459–483.
H. F. Weinberger, A characterization of the Pólya frequency functions of order 3, Applicable Anal. 15 (1983), 53–69.
A. M. Whitney, A reduction theorem for totally positive matrices, J. Anal. Math. 2 (1952), 88–92.
D. V. Widder, Necessary and sufficient conditions for the representation of a function by a doubly infinite Laplace integral, Bull. Amer. Math. Soc. 40 (1934), 321–326.
Acknowledgments
We thank Percy Deift for raising the question of classifying total positivity preservers and pointing out the relevance of such a result for current studies in mathematical physics. We also thank Alan Sokal for his comments on a preliminary version of the paper. A. B. is grateful for the hospitality of the Indian Institute of Science, Bangalore, where part of this work was carried out. D. G. was partially supported by a University of Delaware Research Foundation grant, by a Simons Foundation collaboration grant for mathematicians, and by a University of Delaware strategic initiative grant. A. K. was partially supported by Ramanujan Fellowship grant SB/S2/RJN-121/2017,MATRICS grant MTR/2017/000295, and SwarnaJayanti Fellowship grants SB/SJF/2019-20/14 and DST/SJF/MS/2019/3 from SERB and DST (Govt. of India), by grant F.510/25/CAS-II/2018(SAP-I) from UGC (Govt. of India), and by a Young Investigator Award from the Infosys Foundation. M. P. was partially supported by a Simons Foundation collaboration grant for mathematicians.
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Belton, A., Guillot, D., Khare, A. et al. Totally positive kernels, Pólya frequency functions, and their transforms. JAMA 150, 83–158 (2023). https://doi.org/10.1007/s11854-022-0259-7
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DOI: https://doi.org/10.1007/s11854-022-0259-7