Abstract
In this article, we introduce the concept of general -mixed chord integral difference of star bodies. Further, we establish the Brunn–Minkowski type, Aleksandrov–Fenchel type and cyclic inequalities for the -mixed chord integral difference.
Keywords:
general Lp-mixed chord integral difference; volume difference; Lp-radial Minkowski combination; Lp-radial Blaschke Minkowski homomorphism MSC:
52A20; 52A39; 52A40
1. Introduction
The setting for this paper is n-dimensional Euclidean spaces . Let K and L be two convex bodies (compact, convex subsets with nonempty interiors) in . V denotes the volume. If K is a compact star-shaped (about the origin) set in , then its radial function, , is defined by (see [1]):
If is positive and continuous, K is called a star body (about the origin), and denotes the set of star bodies in . is the subset of containing the origin in their interiors. The unit sphere in is denoted by , and B denotes the standard unit ball in .
The classical Brunn–Minkowski inequality is (see [2])
where + denotes vector or the Minkowski sum of two sets, i.e.,
In 2004, Leng (see [3]) presented a new generalization of the Brunn–Minkowski inequality for the volume difference of convex bodies.
Theorem 1.
Suppose that and D are compact domains, and , is a homothetic copy of D. Then
The equality holds if and only if K and L are homothetic and where μ is a constant.
Leng’s result is a major extension of the classical Brunn–Minkowski inequality and attracts more and more attention (see [4,5,6]).
In 1977, Lutwak introduced the notion of a mixed width-integral of convex bodies (see [7]), and the dual notion, mixed chord-integrals of star bodies was defined by Lu (see [8]). Later, as a part of the asymmetric Brunn–Minkowski theory, which has its origins in the work of Ludwig, Haberl and Schuster (see [9,10,11,12,13]), Feng and Wang generalized the mixed chord-integrals to general mixed chord-integrals of star bodies (see [14]). For and , the general mixed chord-integral is defined by
here, , and the functions and are defined as follows
In 2016, Li and Wang extended the general mixed chord-integral to the general -mixed chord integral of star bodies (see [15]): For , and , the general -mixed chord integral of is defined by
Here, is defined by
for any , and and are chosen as (see [16])
Obviously, and satisfy
denotes that K appears times, and L appears i times, which is
If constants exist such that for all , star bodies are said to have a similar general -chord. For this general -chord integral, Li and Wang gave the following inequalities (see [15]).
Theorem 2.
If and , then for
for or ,
with equality in each inequality if and only if K and L have a similar general -chord. Here and in the following Theorems, denotes the -radial Minkowski combination of K and L.
Theorem 3.
If and , then for ,
with equality if and only if all have a similar general -chord.
Theorem 4.
If and , then for ,
with equality if and only if K and L have a similar general -chord.
2. Main Results
Inspired by Leng’s idea, this article deals with the general -chord integral of star bodies and gives some inequalities for the general -chord integral difference.
Theorem 5.
Let and . If K and L have similar general -chord and , , then for
and for or ,
with equality in each inequality if and only if M and have a similar general -chord.
Theorem 6.
Let and , and . If , have similar general -chord, then for ,
with equality if and only if all have a similar general -chord.
Theorem 7.
Let and . If K and L have similar general -chord, then for ,
with equality if and only if K and L have a similar general -chord.
3. Preliminaries
For , the radial Blaschke linear combination and the radial Minkowski linear combination are defined by Lutwak (see [17]), respectively:
and
In 2007, Schuster introduced the notion of radial Blaschke–Minkowski homomorphism (see [18,19,20,21,22]) as follows.
Definition 1.
A map is called a radial Blaschke–Minkowski homomorphism if it satisfies the following conditions:
- (1)
- is coninuous;
- (2)
- is radial Blaschke Minkowski additive, i.e., for all
- (3)
- intertwines rotations, i.e., , for all and .
Here, denotes the radial sum of and , and is the radial Blaschke sum of the star bodies K and L.
In 2011, Wang et al. (see [23]) extended the notion of radial Blaschke–Minkowski homomorphism to -radial Minkowski homomorphism as follows.
Definition 2.
A map is called an -radial Minkowski homomorphism if it satisfies the following conditions:
- (1)
- is coninuous;
- (2)
- is radial Minkowski additive, i.e., for all
- (3)
- intertwines rotations, i.e., , for all and .
Here, denotes the radial sum of and , i.e., (see [9,24])
For , the -radial Blaschke linear combination was defined by Wang (see [25]):
From Equations (2c) and (2d), we easily obtain
Here, we recall a special -radial Minkowski homomorphism. In 2007, Yu, Wu and Leng (see [26]) introduced the quasi- intersection body of a star body. Let K be a star body in , then the quasi- intersection body of K is defined by:
Further, Wang (see [23]) proved that the operator has the following properties: is continuous with respect to radial metric; for all intertwines rotations, i.e., , for all and , which means that the operator is a special -radial Minkowski homomorphism.
Now, we list three Lemmas useful in the proof of Theorems 5–7.
In 1997, Losonczi and Páles (see [27]) extended Bellman’s inequality as follows:
Lemma 1.
Let and be two sequences of positive real numbers and such that and . Then
If or , then
with equality if and only if , where v is a constant.
Lemma 2
([28], p.26). If , then
with equality if and only if
Lemma 3
([5]). Suppose that are non-negative continuous functions on such that
for , and
where λ is a constant. Then
with equality if and only if for any
4. Proofs of Main Results
In this section, we prove Theorems 5–7.
Proof of Theorem 5.
We only prove Equation (1f). The proof of Equation (1g) is similar to Equation (1f). Let . Since K and L have similar general -chord, by Equation (1b),
for M and ,
Let and , then from Equations (3a) and (3b) and Lemma 1, we have
This gives the desired inequality of Equation (1f) and according to the equality condition of Lemma 1, we obtain that equality holds if and only if M and have a similar general -chord. □
Notice that from the notion of -radial Minkowski homomorphism and Equation (2e), we have the following direct Corollary 1.
Corollary 1.
Let and . is a radial Blaschke–Minkowski homomorphism. K and L have a similar general -chord and , , then for
and for or ,
with equality in each inequality if and only if M and have a similar general -chord.
Further, since the intersection map is a special -radial Minkowski homomorphism, we have the following corollary
Corollary 2.
Let and . If K and L have a similar general -chord and , , then for
and for or ,
with equality in each inequality if and only if M and have a similar general -chord.
Proof of Theorem 6.
Since have a similar general -chord, from (1d) we have for ,
For ,
The condition means that . From Equations (3c) and (3d) and Lemma 2, we obtain
Let and in Lemma 2. Then by Equation (2g)
which implies that Equation (1h) is proved. According to the equality condition of Lemma 2, we know that equality holds in Equation (1h) if and only if all have a similar general -chord. □
Proof of Theorem 7.
For , let . Then, and . Let
and
After a simple calculation, we obtain
The left-hand side of Equation (2h) leads to
By Lemma 3, Equation (1i) immediately holds.
The equality condition of Equation (2h) means that is a constant, that is, K and L have a similar general -chord. This completes the proof. □
5. Conclusions
The asymmetric operators belong to a new and rapidly evolving asymmetric -Brunn–Minkowski theory that has its origins in the work of Ludwig, Haberl and Schuster (see [9,11,12,16,18,19,20]). The general -mixed chord integral difference of star bodies was motivated by the notion of mixed width-integrals of convex bodies. We hope that besides the inequalities mentioned in this article, we can deduce some other inequalities in the future.
Author Contributions
All authors contributed equally and significantly in writing this article. All authors have read and agreed to the published version of the manuscript.
Funding
Supported by the Open Research Fund of Computational physics Key Laboratory of Sichuan province, Yibin University: ybxyjswl-zd-2020-004.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Gardner, R.J. Geometric Tomography, 2nd ed.; Cambridge University Press: Cambridge, UK, 2006. [Google Scholar]
- Gardner, R.J. The Brunn-Minkowski inequality. Bull. Am. Math. Soc. 2002, 39, 355–405. [Google Scholar] [CrossRef]
- Leng, G.S. The Brunn-Minkowski inequality for volume difference. Adv. Appl. Math. 2004, 32, 615–624. [Google Scholar] [CrossRef]
- Feng, Y.B.; Wang, W.D.; Yuan, J. Inequalities of quermassintegrals about mixed Blaschke Minkowski homomorphisms. Tamkang J. Math. 2015, 46, 217–227. [Google Scholar] [CrossRef][Green Version]
- Lv, S.J. Dual Brunn-Minkowski inequality for volume differences. Geom. Dedicata. 2010, 145, 169–180. [Google Scholar] [CrossRef]
- Zhao, C.J. On Blaschke-Minkowski Homomorphisms and Radial Blaschke-Minkowski Homomorphisms. J. Geom. Anal. 2016, 26, 1523–1538. [Google Scholar] [CrossRef]
- Lutwak, E. Mixed width-integrals of convex bodies. Israel J. Math. 1977, 28, 249–253. [Google Scholar] [CrossRef]
- Lu, F.H. Mixed chord-integrals of star bodies. J. Korean Math. Soc. 2010, 47, 277–288. [Google Scholar]
- Haberl, C. Lp intersection bodies. Adv. Math. 2008, 4, 2599–2624. [Google Scholar] [CrossRef]
- Haberl, C. Minkowski valuations intertwining with the special linear group. J. Eur. Math. Soc. 2012, 4, 1565–1597. [Google Scholar] [CrossRef]
- Haberl, C.; Ludwig, M. A characterization of Lp intersection bodies. Int. Math. Res. Not. 2006, 2006, 10548. [Google Scholar] [CrossRef]
- Haberl, C.; Schuster, F.E. Asymmetric affine Lp sobolev inequalities. J. Funct. Anal. 2009, 257, 641–658. [Google Scholar] [CrossRef]
- Haberl, C.; Schuster, F.E.; Xiao, J. An asymmetric affine Po´lya-Szego¨ principle. Math. Ann. 2012, 352, 517–542. [Google Scholar] [CrossRef]
- Feng, Y.B.; Wang, W.D. General mixed chord-integrals of star bodies. Rocky Mt. J. Math. 2016, 46, 1499–1518. [Google Scholar] [CrossRef]
- Li, Z.F.; Wang, W.D. General Lp-mixed chord integrals of star bodies. J. Inequalities Appl. 2016, 58, 1–12. [Google Scholar]
- Haberl, C.; Schuster, F.E. General Lp affine isoperimetric inequalities. J. Differ. Geom. 2009, 83, 1–26. [Google Scholar] [CrossRef]
- Lutwak, E. Intersection bodies and dual mixed volumes. Adv. Math. 1988, 71, 232–261. [Google Scholar] [CrossRef]
- Schuster, F.E. Convolutions and multiplier transformations of convex bodies. Trans. Am. Math. Soc. 2007, 359, 5567–5591. [Google Scholar] [CrossRef]
- Schuster, F.E. Volume inequalities and additive maps of convex bodies. Mathematika 2007, 52, 211–234. [Google Scholar] [CrossRef]
- Schuster, F.E. Valuations and Busemann-Petty type problems. Adv. Math. 2008, 219, 344–368. [Google Scholar] [CrossRef]
- Schuster, F.E. Crofton measures and Minkowski valuations. Duke Math. J. 2010, 154, 1–30. [Google Scholar] [CrossRef]
- Schuster, F.E.; Wannerer, T. GL(n) contravariant Minkowski valuations. Trans. Am. Math. Soc. 2012, 364, 815–826. [Google Scholar] [CrossRef]
- Wang, W.; Liu, L.J.; He, B.W. Lp radial Minkowski homomorphisms. Taiwan. J. Math. 2011, 15, 1183–1199. [Google Scholar] [CrossRef]
- Grinberg, E.; Zhang, G.Y. Convolutions transforms and convex bodies. Proc. Lond. Math. Soc. 1999, 78, 77–115. [Google Scholar] [CrossRef]
- Wang, J.Y.; Wang, W.D. General Lp dual Blaschke bodies and the applications. J. Inequalities Appl. 2015, 2015, 233. [Google Scholar] [CrossRef][Green Version]
- Yu, W.Y.; Wu, D.H.; Leng, G.S. Quasi-Lp intersection bodies. Acta Math. Sin. 2007, 23, 1937–1948. [Google Scholar] [CrossRef]
- Losonczi, L.; Páles, Z.S. Inequalities for indefinite forms. J. Math. Anal. 1997, 205, 148–156. [Google Scholar] [CrossRef]
- Beckenbach, E.F.; Bellman, R. Inequalities, 2nd ed.; Springer: Berlin/Heidelberg, Germany, 1965. [Google Scholar]
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